Home/Quiz/Free Practice Questions for USMLE Step 1 Free Practice Questions for USMLE Step 1 Welcome to your Free Practice Questions for USMLE Step 1 1. A 47-year-old man has intermittent jaundice during fasting. His hemoglobin is normal, reticulocyte count is not elevated, and total bilirubin is mildly increased with an unconjugated predominance. Which hepatic process is most likely reduced? Heme oxygenase activity Bilirubin conjugation by UDP-glucuronosyltransferase Bile acid synthesis Hepatic bilirubin uptake Urea-cycle activity None Hint 2. A 3-year-old boy has developmental delay and a musty body odor. Plasma phenylalanine is markedly elevated. Which dietary change is most appropriate? Increase phenylalanine intake Restrict phenylalanine intake Restrict tyrosine intake Eliminate all branched-chain amino acids Increase methionine intake None Hint 3. A growth-factor receptor on a cancer cell has intrinsic tyrosine kinase activity. After ligand binding, which intracellular protein is most directly activated to initiate the MAP kinase cascade? Ras Protein kinase A IP3 JAK2 Protein kinase C None Hint 4. A 7-month-old infant develops severe fasting hypoglycemia, hepatomegaly, hyperuricemia, and lactic acidosis. Which hepatic enzyme defect best explains the findings? Fructose-1,6-bisphosphatase Glucose-6-phosphatase Glycogen phosphorylase Pyruvate carboxylase Galactose-1-phosphate uridyltransferase None Hint 5. A malnourished patient with chronic alcohol use is given intravenous glucose before receiving vitamin replacement and subsequently develops confusion, gait instability, and ophthalmoplegia. Which deficiency is responsible? Niacin Thiamine Pyridoxine Folate Vitamin B12 None Hint 6. A newborn develops vomiting, jaundice, hepatomegaly, and cataracts after milk feeds are introduced. Which metabolite is expected to accumulate because of the enzyme defect? Galactose-1-phosphate Fructose-1-phosphate Phenylpyruvate Homocysteine Methylmalonic acid None Hint 7. A 10-year-old boy has recurrent pneumonia caused by Serratia and Aspergillus species. Neutrophils show impaired oxidative burst on testing. Which molecular defect is most likely? Myeloperoxidase deficiency NADPH oxidase deficiency CD18 deficiency C3 deficiency Bruton tyrosine kinase deficiency None Hint 8. A biopsy from a rapidly growing tumor shows loss-of-function mutation of a protein that normally arrests cells after DNA damage. Which protein is most likely affected? RB p53 RAS BCL2 MYC None Hint 9. A teenager develops severe muscle cramps and dark urine several hours after prolonged exercise. During a prolonged fast, his skeletal muscle cannot adequately generate ATP from stored energy. Which pathway is most likely defective? Fatty-acid oxidation Pentose phosphate pathway Purine synthesis Ketone-body synthesis Urea cycle None Hint 10. A patient begins a lipid-lowering medication that decreases hepatic cholesterol synthesis by inhibiting the rate-limiting enzyme of the pathway. Which enzyme is targeted? HMG-CoA synthase HMG-CoA reductase Acetyl-CoA carboxylase Lipoprotein lipase LCAT None Hint 11. A patient with elevated LDL cholesterol is prescribed ezetimibe. Which intestinal protein is inhibited? ABCG5 NPC1L1 ApoB-100 LDL receptor Lipoprotein lipase None Hint 12. During a biochemical experiment, a reaction in the citric acid cycle directly generates a high-energy phosphate without using the electron transport chain. Which reaction is responsible? Citrate to isocitrate Isocitrate to alpha-ketoglutarate Succinyl-CoA to succinate Succinate to fumarate Malate to oxaloacetate None Hint 13. A patient with insulin resistance has persistent fasting hyperglycemia despite elevated insulin levels. Which hepatic process is relatively increased because insulin fails to suppress it? Glycogen synthesis Glycolysis Gluconeogenesis Fatty-acid synthesis Glucose uptake by GLUT4 None Hint 14. A severely fasting patient requires an amino acid that cannot provide net glucose but can provide acetyl-CoA-derived ketone-body precursors. Which amino acid is purely ketogenic? Alanine Valine Leucine Aspartate Serine None Hint 15. A child with a urea-cycle disorder develops hyperammonemia. Which compound can be administered as part of therapy to promote nitrogen disposal through an alternative pathway? Arginine Tyrosine Phenylalanine Tryptophan Methionine None Hint 16. A patient with chronic alcohol use has elevated lactate after a carbohydrate-rich meal. Which cofactor derived from a vitamin is required by pyruvate dehydrogenase? Biotin Thiamine pyrophosphate Pyridoxal phosphate Tetrahydrofolate Cobalamin None Hint 17. A boy has intellectual disability, elongated face, large ears, and macroorchidism. Genetic testing identifies an expanded CGG repeat in a gene on the X chromosome. What mechanism explains the disease? Nondisjunction Trinucleotide repeat expansion Mitochondrial inheritance Uniparental disomy Balanced translocation None Hint 18. A woman with a pathogenic BRCA1 variant asks about inheritance. Her father is healthy but carries the mutation. Which inheritance pattern best describes the cancer predisposition? Autosomal dominant Autosomal recessive X-linked recessive Mitochondrial Y-linked None Hint 19. A male infant has recurrent infections, absent tonsils, and very low numbers of mature B cells. Genetic testing identifies an IL2RG mutation. Which inheritance pattern is expected? Autosomal dominant Autosomal recessive X-linked recessive X-linked dominant Mitochondrial None Hint 20. A woman with a mitochondrial DNA mutation asks about transmission to her children. Assuming the mutation is present in essentially all of her oocytes, which pattern is expected? Only sons inherit it Only daughters inherit it Approximately half inherit it All children inherit mitochondrial DNA from her No children inherit it None Hint 21. A 5-year-old boy with severe hyperphagia and obesity has developmental delay and hypogonadism. Testing shows maternal uniparental disomy involving chromosome 15. Which diagnosis is most likely? Angelman syndrome Prader-Willi syndrome Fragile X syndrome DiGeorge syndrome Williams syndrome None Hint 22. A man with sickle cell disease has a child with a woman who has sickle cell trait. What is the probability that their next child will have HbSS disease? 0% 25% 50% 75% 100% None Hint 23. A secretory cell produces a peptide hormone that must be exported from the cell. Which ribosome population synthesizes the precursor protein? Free cytosolic ribosomes Ribosomes bound to rough ER Mitochondrial ribosomes Nucleolar ribosomes Peroxisomal ribosomes None Hint 24. A child has coarse facial features, hepatosplenomegaly, and developmental delay. Urinary testing shows excessive glycosaminoglycans. Which cellular organelle is primarily involved? Peroxisome Lysosome Golgi apparatus Mitochondrion Nucleus None Hint 25. A pathology specimen shows a structural protein network that provides tensile strength to epithelial cells and resists mechanical stress. Which cytoskeletal component is most responsible? Actin microfilaments Intermediate filaments Microtubules Dynein Myosin None Hint 26. A child with leukemia receives vincristine. Which cellular structure is directly disrupted by this drug? Actin filaments Microtubules of the mitotic spindle Intermediate filaments Desmosomes Nuclear pores None Hint 27. A man has chronic sinusitis, bronchiectasis, infertility, and situs inversus. Which molecular component of respiratory cilia is most likely defective? Kinesin light chains Dynein arms Actin rings Intermediate filaments Gap junctions None Hint 28. A patient with a blistering skin disorder has antibodies against proteins that link keratin intermediate filaments between adjacent epidermal cells. Which junction is targeted? Tight junction Adherens junction Desmosome Gap junction Hemidesmosome None Hint 29. A previously unvaccinated adult develops a first-time infection. Which antibody class is expected to appear first and activate complement most efficiently? IgA IgD IgE IgG IgM None Hint 30. A 9-month-old boy develops recurrent otitis and bacterial pneumonia after maternal antibodies have waned. He has very low mature B-cell numbers but normal T-cell numbers. Which defect is most likely? BTK mutation AIRE mutation IL2RG mutation 22q11 deletion CD40L mutation None Hint 31. A macrophage infected with an intracellular bacterium is strongly activated by a cytokine released from Th1 cells. Which cytokine is most important? IL-4 IL-5 IFN-gamma IL-10 IL-13 None Hint 32. An Rh-negative mother has an Rh-positive fetus. Maternal antibodies later cross the placenta and cause fetal red-cell destruction. Which immunoglobulin is responsible? IgA IgE IgG IgM IgD None Hint 33. A virus infects a nucleated host cell and produces proteins in the cytosol. Which antigen-presentation pathway displays these peptides to cytotoxic T cells? MHC class I MHC class II CD1 B-cell receptor Fc receptor None Hint 34. A 4-year-old boy has eczema, recurrent infections, and thrombocytopenia. His platelet count is low and the platelets are unusually small. Which diagnosis is most likely? DiGeorge syndrome Wiskott-Aldrich syndrome CVID Chronic granulomatous disease Ataxia-telangiectasia None Hint 35. A dendritic cell captures antigen in peripheral tissue and migrates to a regional lymph node. Which function is it best equipped to perform there? Secrete antibodies Activate naive T cells Destroy infected erythrocytes Produce complement Release histamine None Hint 36. A patient develops fever, arthralgia, and proteinuria 10 days after receiving a foreign protein-containing antivenom. Immune complexes are detected in the circulation. Which hypersensitivity type is involved? Type I Type II Type III Type IV Type V None Hint 37. A patient develops prosthetic-valve endocarditis several weeks after surgery. Blood cultures grow catalase-positive, coagulase-negative gram-positive cocci that form a biofilm. Which organism is most likely? Staphylococcus aureus Staphylococcus epidermidis Streptococcus pyogenes Enterococcus faecalis Streptococcus pneumoniae None Hint 38. A hospitalized patient develops watery diarrhea after receiving clindamycin. Colonoscopy shows raised yellow-white plaques over the colonic mucosa. Which organism is responsible? Clostridioides difficile Vibrio cholerae Shigella sonnei Campylobacter jejuni Salmonella Typhi None Hint 39. A patient with advanced HIV develops headache and confusion. CSF shows an encapsulated yeast with narrow-based budding. Which pathogen is most likely? Cryptococcus neoformans Candida albicans Aspergillus fumigatus Histoplasma capsulatum Coccidioides immitis None Hint 40. A college student presents with fever, neck stiffness, photophobia, and a petechial rash. CSF shows neutrophils and low glucose, and gram-negative diplococci are seen. Which vaccine is most directly protective? Hepatitis B vaccine Meningococcal vaccine Pneumococcal vaccine Hib vaccine Varicella vaccine None Hint 41. A 22-year-old man develops fever and inflammatory diarrhea after eating undercooked poultry. Stool culture grows a curved, oxidase-positive gram-negative rod that grows best at reduced oxygen tension. Which organism is most likely? Campylobacter jejuni Shigella dysenteriae Yersinia enterocolitica Vibrio parahaemolyticus Enterotoxigenic E. coli None Hint 42. A patient develops a painless genital ulcer with nontender regional lymphadenopathy. A spirochete is identified at the lesion. Which stage of syphilis is represented? Primary Secondary Tertiary Latent Congenital None Hint 43. A child has fever, cough, conjunctivitis, and small white lesions on the buccal mucosa before developing a descending maculopapular rash. Which vaccine prevents this illness? MMR DTaP IPV Hepatitis A Hib None Hint 44. A traveler returns from a tropical region with high fever, severe myalgias, thrombocytopenia, capillary leak, and bleeding after a second febrile illness. Which virus is most likely? Dengue virus Rabies virus Yellow fever virus Hepatitis A virus Ebola virus None Hint 45. A 6-year-old child has severe microcytic anemia despite iron supplementation. Blood smear shows numerous target cells, and hemoglobin electrophoresis shows a marked increase in HbF. Which diagnosis is most likely? Iron deficiency anemia Beta-thalassemia major Sickle cell trait Hereditary spherocytosis G6PD deficiency None Hint 46. A patient taking warfarin for a mechanical valve asks why consistent dietary habits are recommended. Which nutrient most directly antagonizes the drug's effect? Vitamin A Vitamin C Vitamin D Vitamin K Vitamin B12 None Hint 47. A child has recurrent bacterial and opportunistic infections with unusually low IgG, IgA, and IgE but relatively preserved IgM. Which disorder of B-cell function is most likely? Selective IgA deficiency Hyper-IgM syndrome X-linked agammaglobulinemia CVID DiGeorge syndrome None Hint 48. A lymph-node biopsy from a patient with Hodgkin lymphoma shows classic Reed-Sternberg cells. Which immunophenotype is most characteristic of classical Hodgkin lymphoma? CD3+ only CD15+ and CD30+ CD20+ and CD79a strongly positive only TdT+ CD8+ only None Hint 49. A patient with chronic lymphocytic leukemia develops a positive direct antiglobulin test and hemolytic anemia. Which hypersensitivity mechanism best explains the hemolysis? Type I Type II Type III Type IV Immune tolerance None Hint 50. A 68-year-old man has splenomegaly, anemia, and a leukoerythroblastic blood smear. Bone marrow aspiration yields a dry tap, and biopsy shows extensive fibrosis with atypical megakaryocytes. What is the diagnosis? Aplastic anemia Primary myelofibrosis Acute lymphoblastic leukemia Multiple myeloma Iron deficiency anemia None Hint 51. A 58-year-old man develops acute chest pain and ST elevation in leads II, III, and aVF. Which coronary artery is most likely occluded in a right-dominant circulation? Left anterior descending artery Right coronary artery Left circumflex artery Left main coronary artery Posterior descending artery only None Hint 52. A 12-year-old develops migratory polyarthritis and carditis several weeks after untreated streptococcal pharyngitis. Which valve is most often affected in rheumatic heart disease? Aortic Mitral Tricuspid Pulmonary None of the valves None Hint 53. A patient with nonvalvular atrial fibrillation is started on an oral anticoagulant. Which group of coagulation factors is reduced by warfarin? II, VII, IX, X I, V, VIII, XIII VIII, IX, XI, XII V, VII, VIII, XII II, V, VIII, XI None Hint 54. A 63-year-old man develops abrupt tearing chest pain radiating between the scapulae. There is a marked difference in blood pressure between his arms. Which diagnosis is most likely? Acute pericarditis Aortic dissection Pulmonary embolism Esophageal rupture Acute myocardial infarction None Hint 55. A patient with severe chronic kidney disease develops pleuritic chest discomfort and a pericardial friction rub without evidence of infection or infarction. What is the most likely cause? Uremic pericarditis Viral pericarditis Dressler syndrome Tuberculous pericarditis Purulent pericarditis None Hint 56. A 76-year-old man has exertional syncope and angina. Examination reveals a harsh crescendo-decrescendo systolic murmur at the right upper sternal border that radiates to the carotids. What is the diagnosis? Aortic regurgitation Aortic stenosis Mitral stenosis Mitral regurgitation Hypertrophic cardiomyopathy None Hint 57. A patient with Wolff-Parkinson-White syndrome develops atrial fibrillation with a very rapid ventricular rate. Which medication should be avoided because it can favor conduction through the accessory pathway? Procainamide Ibutilide Digoxin Electrical cardioversion Flecainide None Hint 58. A 42-year-old patient has familial dilated cardiomyopathy with severe systolic dysfunction. Genetic testing is performed. Which gene is a common cause of inherited dilated cardiomyopathy? TTN APC RB1 CFTR HFE None Hint 59. A patient develops a persistent dry cough several weeks after starting lisinopril. Which mediator has accumulated? Angiotensin II Aldosterone Bradykinin Endothelin-1 Histamine None Hint 60. A 39-year-old woman develops fever and a new murmur after a dental procedure. Blood cultures grow viridans streptococci. Which valve is most likely involved in this subacute endocarditis? Mitral Pulmonary Tricuspid Aortic only None; viridans does not cause endocarditis None Hint 61. A long-term smoker has a hilar lung mass, recurrent post-obstructive pneumonia, and hypercalcemia. Which tumor is most likely? Adenocarcinoma Squamous cell carcinoma Small-cell carcinoma Typical carcinoid Mesothelioma None Hint 62. A patient with asthma develops severe bronchospasm after exposure to an allergen. Which mediator directly produces powerful and sustained bronchoconstriction? Leukotrienes C4, D4, and E4 Bradykinin Nitric oxide Prostacyclin Endothelin only None Hint 63. A 31-year-old woman develops pleuritic chest pain after a 12-hour flight. CT angiography confirms pulmonary embolism. Which vessel is the most likely source of the thrombus? Portal vein Deep veins of the lower extremities Pulmonary veins Superior vena cava Renal vein None Hint 64. A patient with severe COPD has pH 7.28 and PaCO2 68 mmHg. Serum bicarbonate is elevated. Which acid-base disorder is present? Acute respiratory alkalosis Chronic respiratory acidosis with compensation Metabolic acidosis Metabolic alkalosis Acute respiratory acidosis without compensation None Hint 65. A patient with small-cell lung cancer develops confusion and a serum sodium of 118 mEq/L. Urine is inappropriately concentrated. Which endocrine abnormality is most likely? Excess aldosterone Excess ADH Excess cortisol ADH deficiency Excess renin None Hint 66. A 29-year-old woman has dry cough, dyspnea, bilateral hilar adenopathy, and noncaseating granulomas. Which immune cell population drives the granulomatous response? CD8 T cells Th1 CD4 T cells Neutrophils B cells Eosinophils None Hint 67. A 29-week premature infant develops respiratory distress and diffuse reticulogranular opacities on chest radiography. Which substance is deficient? Surfactant Alpha-1 antitrypsin Elastin Immunoglobulin A Pulmonary vasodilator prostacyclin None Hint 68. A patient has recurrent spontaneous pneumothoraces, multiple lung cysts, and renal tumors. His father had similar disease. Which gene is most likely mutated? FBN1 FLCN PKD1 RET VHL None Hint 69. A hospitalized patient develops a complicated parapneumonic effusion with pus. In community-acquired infection, which organism is a common cause? Streptococcus pneumoniae Pseudomonas aeruginosa Mycoplasma pneumoniae Legionella pneumophila Mycobacterium tuberculosis None Hint 70. A 35-year-old nonsmoker has early emphysema predominantly involving the lower lobes. Which deficiency is most likely? Alpha-1 antitrypsin Surfactant protein B Antithrombin III Ceruloplasmin C1 esterase inhibitor None Hint 71. A patient has generalized edema, heavy proteinuria, hypoalbuminemia, and hyperlipidemia. Which component of the glomerular filtration barrier is commonly injured in nephrotic syndrome? Podocytes Macula densa only Collecting-duct principal cells Proximal tubular brush border Juxtaglomerular cells None Hint 72. A patient with rapidly progressive glomerulonephritis has hemoptysis and a positive anti-GBM antibody test. Which second organ is directly targeted? Liver Lung Pancreas Thyroid Skin None Hint 73. A 70-year-old woman with diabetic kidney disease develops acute kidney injury after iodinated contrast. Which baseline finding confers the greatest risk? Normal renal function Chronic kidney disease Mild isolated anemia Hyperthyroidism Asthma None Hint 74. A renal biopsy in a patient with long-standing diabetes shows nodular mesangial expansion. Which diagnosis is represented? Minimal change disease Diabetic nephropathy Membranous nephropathy IgA nephropathy Poststreptococcal glomerulonephritis None Hint 75. A patient with polyuria has a serum sodium of 151 mEq/L and very dilute urine. Water deprivation fails to concentrate the urine, but desmopressin produces a marked increase in urine osmolality. What is the diagnosis? Nephrogenic diabetes insipidus Central diabetes insipidus Primary polydipsia SIADH Osmotic diuresis from glucose None Hint 76. A patient with advanced chronic kidney disease has elevated phosphate, low calcium, and high parathyroid hormone. What initiates the secondary hyperparathyroidism? Phosphate retention and reduced calcitriol production Primary parathyroid adenoma Excess calcitonin Increased intestinal calcium absorption Excess aldosterone None Hint 77. A 44-year-old woman has hypertension, episodic hematuria, and enlarged kidneys containing numerous bilateral cysts. Several relatives have the same disease. What is the inheritance pattern? Autosomal dominant Autosomal recessive X-linked recessive Mitochondrial Y-linked None Hint 78. A man with sickle cell disease develops painless gross hematuria. Which renal complication is most likely? Renal papillary necrosis Renal cell carcinoma Minimal change disease Renal vein thrombosis Polycystic kidney disease None Hint 79. A patient with chronic hepatitis C has markedly elevated transaminases. Which pattern is most typical of uncomplicated viral hepatocellular injury? AST much greater than ALT ALT greater than AST Isolated alkaline phosphatase elevation Isolated bilirubin elevation Normal transaminases None Hint 80. A 46-year-old man has recurrent epigastric pain that improves after meals and returns several hours later. Endoscopy shows a duodenal ulcer. Which organism is most strongly associated? H. pylori C. difficile S. aureus Giardia lamblia Entamoeba histolytica None Hint 81. A patient with ulcerative colitis develops cholestatic liver tests and multifocal strictures of the intrahepatic and extrahepatic bile ducts. Which diagnosis is most likely? Primary biliary cholangitis Primary sclerosing cholangitis Autoimmune hepatitis Choledocholithiasis Wilson disease None Hint 82. A patient with biopsy-proven celiac disease continues to have villous atrophy and diarrhea after 12 months of a carefully supervised gluten-free diet. Which diagnosis should be considered? Refractory celiac disease Acute appendicitis Lactose intolerance only Whipple disease in every case Zollinger-Ellison syndrome None Hint 83. A patient with advanced cirrhosis develops confusion, sleep-wake reversal, and asterixis. Which substance contributes most directly to the neurotoxicity? Ammonia Bilirubin Urea Albumin Conjugated bile acids None Hint 84. A man with portal hypertension has a large upper gastrointestinal bleed from esophageal varices. Which portal-systemic connection is responsible? Left gastric vein with esophageal veins Splenic artery with azygos vein Inferior mesenteric artery with IVC Portal vein with pulmonary vein Superior mesenteric artery with renal vein None Hint 85. A newborn has abdominal distension and fails to pass meconium. Rectal biopsy demonstrates absent enteric ganglion cells. Which gene is classically associated? RET APC RB1 CFTR only HFE None Hint 86. A patient with longstanding Crohn colitis undergoes surveillance colonoscopy. A biopsy shows confirmed high-grade dysplasia in an area of colonic mucosa. What is the usual management? Ignore the finding Prophylactic colectomy Treat with antacids only Appendectomy Observe indefinitely None Hint 87. A 48-year-old woman develops severe epigastric pain radiating to the back. She has gallstones on ultrasound. What is the most common cause of acute pancreatitis in many clinical settings? Gallstones Celiac disease Ulcerative colitis Appendicitis Hepatitis B None Hint 88. A patient has recurrent peptic ulcers despite maximal acid suppression and has chronic watery diarrhea. Fasting serum gastrin is extremely elevated. Which tumor is most likely? Insulinoma Gastrinoma Glucagonoma Somatostatinoma VIPoma None Hint 89. A 52-year-old woman has symmetric MCP and PIP joint swelling with prolonged morning stiffness. Which antibody is most specific for rheumatoid arthritis? ANA Anti-CCP Anti-mitochondrial antibody Anti-centromere antibody p-ANCA None Hint 90. A 72-year-old woman has osteoporosis and a recent vertebral compression fracture. Which medication directly inhibits osteoclast-mediated bone resorption and reduces hip-fracture risk? Alendronate Teriparatide only Calcitonin only Levothyroxine Cinacalcet None Hint 91. A patient develops diffuse muscle pain and cola-colored urine several weeks after starting a high-dose statin. CK is markedly elevated. Which complication has occurred? Rhabdomyolysis Myasthenia gravis Peripheral neuropathy Gout Osteomalacia None Hint 92. A 26-year-old man has chronic inflammatory back pain that improves with exercise. Imaging shows sacroiliitis and syndesmophytes. Which genetic marker is associated? HLA-B27 HLA-DR2 HLA-DQ2 HLA-B8 HLA-DR4 None Hint 93. A patient develops grouped vesicles and burning pain in a band-like distribution over one side of the chest. Which pathogen is responsible? HSV-1 Varicella-zoster virus Parvovirus B19 Molluscum contagiosum virus Coxsackievirus A16 None Hint 94. A patient with chronic plaque psoriasis develops inflammatory pain and swelling of several DIP joints with nail pitting. Which diagnosis is most likely? Rheumatoid arthritis Psoriatic arthritis Osteoarthritis Gout Reactive arthritis None Hint 95. A woman develops tender red nodules over the anterior shins after an inflammatory illness. Biopsy shows inflammation of subcutaneous fat without vasculitis. What is the diagnosis? Erythema nodosum Erythema multiforme Pyoderma gangrenosum Urticaria Psoriasis None Hint 96. A patient develops targetoid lesions with blistering and painful oral erosions shortly after starting a new medication. What is the most likely diagnosis? Stevens-Johnson syndrome Psoriasis Pemphigus vulgaris Urticaria Erythema nodosum None Hint 97. A 19-year-old woman with type 1 diabetes stops taking insulin because of nausea. She develops abdominal pain, Kussmaul respirations, and an anion-gap metabolic acidosis. Which substance accounts for most of the excess anion? Lactate Ketoacids Bicarbonate Chloride Urea None Hint 98. A 34-year-old woman has weight loss, heat intolerance, tremor, diffuse goiter, and a suppressed TSH. Which antibody is most likely present? Anti-thyroid peroxidase only TSH-receptor stimulating antibody Anti-dsDNA Anti-mitochondrial antibody Anti-CCP None Hint 99. A woman with amenorrhea has galactorrhea and a pituitary mass on MRI. Which hormone is most likely elevated? ACTH Growth hormone Prolactin FSH ADH None Hint 100. A newborn has ambiguous genitalia, hypotension, hyponatremia, hyperkalemia, and markedly elevated 17-hydroxyprogesterone. Which enzyme is deficient? 11-beta hydroxylase 21-hydroxylase 17-alpha hydroxylase Aromatase 5-alpha reductase None Hint 101. A 30-year-old woman has depressed mood, loss of interest, low energy, impaired concentration, and increased sleep for 1 month. She has no history of mania. Which diagnosis is most likely? Bipolar I disorder Major depressive disorder Cyclothymic disorder Persistent depressive disorder Adjustment disorder None Hint 102. A patient has repeated episodes of elevated mood, decreased need for sleep, grandiosity, rapid speech, and impulsive spending, followed by major depressive episodes. Which medication is commonly used for long-term mood stabilization? Lithium Fluoxetine alone Methylphenidate Buspirone Haloperidol only None Hint 103. A college student suddenly becomes unable to move her legs after a major interpersonal conflict. Neurologic examination and imaging are normal, and symptoms are inconsistent with anatomic pathways. Which defense mechanism best describes the symptom? Projection Conversion Displacement Rationalization Regression None Hint 104. A 17-year-old survives an intentional medication overdose. Which historical feature is the strongest predictor of another suicide attempt? Being an only child Previous suicide attempt Normal appetite Good academic performance No family psychiatric history None Hint 105. A patient with schizophrenia continues to hear voices and believes others are plotting against him. These symptoms are classified as which type? Negative symptoms Positive symptoms Cognitive symptoms only Mood-congruent symptoms Dissociative symptoms None Hint 106. A patient has excessive uncontrollable worry about finances, family, work, and health for 8 months. He has muscle tension and poor sleep. Which diagnosis is most likely? Panic disorder Generalized anxiety disorder Social anxiety disorder OCD PTSD None Hint 107. A patient develops recurrent nightmares, intrusive memories, avoidance, and hypervigilance 4 months after surviving a severe motor-vehicle crash. Which diagnosis is most likely? Acute stress disorder PTSD Panic disorder Adjustment disorder Specific phobia None Hint 108. A hospitalized patient with heavy daily alcohol use becomes tremulous, anxious, and tachycardic 12 hours after admission. Which medication is preferred to prevent withdrawal seizures? Lorazepam Haloperidol Fluoxetine Naltrexone Disulfiram None Hint 109. A young woman with anorexia nervosa has a potassium concentration of 2.5 mEq/L after recurrent vomiting and laxative use. Which complication poses the most immediate cardiac risk? Hypercalcemia Hypokalemia-related arrhythmia Hypernatremia Respiratory alkalosis Polycythemia None Hint 110. A patient with chronic pain requests escalating opioid doses, spends increasing time obtaining medication, and continues use despite social consequences. Which phenomenon is most likely? Tolerance only Substance use disorder Placebo response Withdrawal only Pseudoallergy None Hint 111. A 66-year-old man develops sudden right-sided weakness involving the face, arm, and leg. MRI shows a small infarct in the posterior limb of the left internal capsule. Which vessel is most likely involved? Lenticulostriate arteries Anterior cerebral artery Posterior cerebral artery Middle meningeal artery Superior cerebellar artery None Hint 112. A 28-year-old woman has fluctuating ptosis and diplopia that worsen late in the day and improve after rest. Which antibody is most likely? Anti-ACh receptor Anti-dsDNA Anti-MOG Anti-voltage-gated calcium channel Anti-GAD None Hint 113. A patient develops unilateral facial weakness involving the forehead, inability to close the eye, and loss of taste from the anterior tongue. Which nerve is affected? CN V CN VII CN IX CN X CN XII None Hint 114. A 69-year-old man has resting tremor, bradykinesia, rigidity, and a shuffling gait. Which neurotransmitter deficiency underlies the motor syndrome? Dopamine Serotonin GABA Acetylcholine Glutamate None Hint 115. A patient suddenly loses vision in the right eye. Ophthalmoscopy shows a normal retina but a relative afferent pupillary defect. Which structure is most likely affected? Right optic nerve Optic chiasm Left optic tract Right occipital cortex Left optic radiation None Hint 116. A patient develops ascending weakness and areflexia two weeks after an episode of gastroenteritis. CSF shows high protein with a normal cell count. What is the diagnosis? Multiple sclerosis Guillain-Barré syndrome Myasthenia gravis ALS Botulism None Hint 117. A 27-year-old woman has episodes of optic neuritis and diplopia. MRI shows multiple periventricular lesions perpendicular to the ventricles. What pathologic process best explains the disease? Demyelination Axonal regeneration Peripheral nerve compression Neuromuscular-junction blockade Neuronal migration failure None Hint 118. A malnourished patient with chronic alcohol use has confusion, ataxia, and ophthalmoplegia. Which metabolic reaction is impaired by the underlying vitamin deficiency? Pyruvate dehydrogenase DNA replication Urea synthesis only Fatty-acid beta-oxidation only Cholesterol esterification None Hint 119. A child has seizures, developmental delay, facial angiofibromas, and a cortical lesion. Genetic testing identifies a pathogenic variant in a tumor-suppressor pathway controlling mTOR signaling. Which disorder is most likely? Tuberous sclerosis complex Neurofibromatosis type 1 Von Hippel-Lindau disease Sturge-Weber syndrome Marfan syndrome None Hint 120. A patient develops sudden violent, irregular flinging movements of the left arm and leg. Which lesion is most likely? Right subthalamic nucleus Left caudate nucleus Right substantia nigra Left cerebellar hemisphere Right hippocampus None Hint 121. A patient has left-sided spasticity, hyperreflexia, and loss of vibration and proprioception, while pain and temperature remain intact. Where is the lesion most likely located? Right dorsal column and corticospinal tract Left spinothalamic tract Right spinothalamic tract only Left dorsal column only Right cerebellar hemisphere None Hint 122. A 62-year-old man has progressive headache and personality change. MRI reveals an irregular ring-enhancing mass with central necrosis and surrounding edema. Biopsy shows pseudopalisading necrosis and microvascular proliferation. What is the diagnosis? Meningioma Glioblastoma Schwannoma Oligodendroglioma Pituitary adenoma None Hint 123. A hospitalized patient develops high fever, hypotension, diffuse erythema, and multiorgan dysfunction. Cultures grow Staphylococcus aureus. Which toxin is classically associated with this syndrome? TSST-1 Shiga toxin Cholera toxin Botulinum toxin Pertussis toxin None Hint 124. A patient with a history of immediate penicillin anaphylaxis develops urticaria and bronchospasm shortly after receiving a related beta-lactam. Which immune mechanism is responsible? IgG immune complexes IgE-mediated mast-cell activation CD8 T-cell cytotoxicity IgM complement activation Delayed T-cell hypersensitivity None Hint 125. A woman has malar rash, photosensitivity, oral ulcers, arthritis, proteinuria, and anti-dsDNA antibodies. Which organ involvement is most strongly associated with increased mortality? Kidney Skin only Thyroid Skeletal muscle Pancreas None Hint 126. A patient with metastatic melanoma develops severe diarrhea two weeks after receiving an immune checkpoint inhibitor. Colonoscopy shows inflammatory colitis. Which mechanism explains this toxicity? Direct bacterial invasion Enhanced T-cell activity against self tissues IgE-mediated allergy Complement deficiency Reduced T-cell activation None Hint 127. A patient with severe sepsis develops bilateral pulmonary infiltrates and profound hypoxemia despite no evidence of cardiogenic pulmonary edema. Which mechanism is central to ARDS? Increased alveolar-capillary permeability Left ventricular failure Bronchial smooth-muscle contraction only Pleural effusion alone Pulmonary embolic obstruction None Hint 128. A patient with septic shock develops fever, vasodilation, hypotension, and capillary leak. Which cytokines are central early mediators of the systemic inflammatory response? TNF-alpha and IL-1 IL-4 and IL-5 IL-10 only TGF-beta only Erythropoietin and renin None Hint 129. A patient has fatigue, weight loss, diffuse hyperpigmentation, hyponatremia, hyperkalemia, and low cortisol. Which diagnosis is most likely? Primary adrenal insufficiency Cushing syndrome Primary hyperaldosteronism SIADH Pheochromocytoma None Hint 130. A kidney-transplant recipient develops rising creatinine, fever, and graft tenderness three weeks after transplantation. Biopsy shows lymphocytic infiltration of the graft. Which type of rejection is most likely? Hyperacute rejection Acute cellular rejection Chronic rejection Graft-versus-host disease No rejection None Hint 131. A patient with advanced HIV develops violaceous skin lesions and lymph-node abnormalities. The associated tumor is driven by a herpesvirus. Which virus is implicated? EBV HHV-8 CMV HSV-2 Parvovirus B19 None Hint 132. A patient develops fever, rash, eosinophilia, and a rise in creatinine 10 days after starting a beta-lactam antibiotic. Urinalysis shows white-cell casts. What is the diagnosis? Acute tubular necrosis Acute interstitial nephritis Minimal change disease Renal papillary necrosis Postrenal obstruction None Hint 133. A pathology report describes a malignant tumor with high-grade cellular atypia and numerous mitotic figures. Which feature is used to determine the stage rather than the grade? Degree of differentiation Mitotic rate Tumor size and nodal/metastatic spread Nuclear pleomorphism Histologic architecture None Hint 134. A breast biopsy shows malignant epithelial cells infiltrating through the basement membrane into surrounding stroma. Which finding establishes invasive carcinoma? High mitotic rate alone Nuclear pleomorphism alone Stromal invasion Increased estrogen receptor expression Necrosis alone None Hint 135. A patient dies five days after a large myocardial infarction. Which histologic finding would be expected in the infarcted myocardium at this time? Neutrophils dominate with no macrophages Macrophage-mediated removal of necrotic tissue with early granulation tissue Mature dense collagen scar No inflammatory cells Caseous necrosis None Hint 136. A lung biopsy from a patient with chronic cough shows granulomas containing amorphous, cheese-like central material. Which type of necrosis is present? Liquefactive Coagulative Caseous Fat Fibrinoid None Hint 137. A patient with chronic airway irritation develops replacement of normal respiratory epithelium by stratified squamous epithelium. Which cellular adaptation is occurring? Hypertrophy Hyperplasia Metaplasia Dysplasia Anaplasia None Hint 138. A cardiac biopsy shows enlarged myocytes with increased cytoplasmic volume and numerous mitochondria in response to chronic pressure overload. Which adaptation is occurring? Atrophy Hypertrophy Hyperplasia Metaplasia Dysplasia None Hint 139. A tumor contains a mutation in a gene that normally binds E2F and restrains the G1-to-S transition. Which gene is mutated? RB1 RAS MYC BCL2 HER2 None Hint 140. A patient with a newly diagnosed epithelial malignancy is found to have multiple regional lymph-node metastases. Which route of spread is most typical of carcinomas? Lymphatic Hematogenous only Transcoelomic only Perineural only Direct spread never occurs None Hint 141. A patient with atrial fibrillation starts an antiarrhythmic that prolongs the QT interval. Which ventricular arrhythmia is the most feared complication? Torsades de pointes Sinus bradycardia only Atrial flutter First-degree AV block only Asystole from vagal tone None Hint 142. A patient receiving cytotoxic chemotherapy develops profound neutropenia. Which drug can shorten the duration of chemotherapy-induced neutropenia? Filgrastim Epoetin alfa Romiplostim Desmopressin Warfarin None Hint 143. A patient with heart failure takes lisinopril and spironolactone and develops potassium of 6.8 mEq/L. Which ECG finding is expected early in significant hyperkalemia? Peaked T waves Prominent U waves QT prolongation ST depression only Delta waves None Hint 144. A man with metastatic prostate cancer receives a long-acting GnRH agonist. After several weeks, testosterone levels fall to castrate levels. Which mechanism explains the effect? Continuous GnRH stimulation suppresses pituitary LH/FSH release after an initial flare Direct destruction of Leydig cells Competitive blockade of androgen receptors Inhibition of 5-alpha reductase only Direct inhibition of testosterone synthesis in the adrenal cortex None Hint 145. A patient being treated for tuberculosis notices that tears and urine have turned orange-red. Which drug causes this adverse effect? Isoniazid Rifampin Ethambutol Pyrazinamide Streptomycin None Hint 146. A screening test has sensitivity of 95% and specificity of 90%. In a population where disease prevalence rises from 10% to 50%, what happens to the positive predictive value? It decreases It increases It remains exactly unchanged It becomes equal to sensitivity It becomes zero None Hint 147. In a randomized trial, mortality is 5% with a new treatment and 10% with placebo. What is the number needed to treat to prevent one additional death? 5 10 20 50 100 None Hint 148. Investigators compare prior smoking exposure between patients with lung cancer and matched controls without lung cancer. Which measure of association is most appropriate? Relative risk Odds ratio Risk difference Hazard ratio only Number needed to treat None Hint 149. A randomized trial reports p = 0.03 for its primary outcome. Which interpretation is correct? There is a 3% chance the null hypothesis is true If the null hypothesis were true, results this extreme or more would occur about 3% of the time The treatment has a 97% probability of being effective The effect size is 3% There is a 3% chance of replication None Hint 150. A 50-year-old asymptomatic adult undergoes a fecal occult blood test as part of cancer screening. Which level of prevention does this represent? Primary Secondary Tertiary Quaternary Rehabilitative None Hint 151. During pelvic surgery, a patient develops weakness of hip abduction due to injury of a nerve supplying gluteus medius and minimus. Which nerve was injured? Femoral nerve Obturator nerve Superior gluteal nerve Inferior gluteal nerve Sciatic nerve None Hint 152. A patient develops hoarseness after thyroidectomy. The surgeon notes an injury close to the inferior pole of the thyroid gland. Which nerve is most likely affected? External laryngeal nerve Recurrent laryngeal nerve Hypoglossal nerve Phrenic nerve Glossopharyngeal nerve None Hint 153. A patient sustains a midshaft humeral fracture and later cannot extend the wrist. Sensation is reduced over the dorsal first web space. Which nerve is injured? Median Ulnar Radial Musculocutaneous Axillary None Hint 154. After a fibular-neck injury, a patient cannot dorsiflex the foot and has numbness in the first web space. Which nerve is injured? Tibial nerve Common fibular nerve Deep fibular nerve Sural nerve Femoral nerve None Hint 155. During laparoscopic cholecystectomy, the surgeon identifies the cystic artery within the hepatocystic triangle. From which vessel does it most commonly arise? Right hepatic artery Left gastric artery Splenic artery Superior mesenteric artery Gastroduodenal artery None Hint 156. A smoker with an apical lung tumor develops ptosis, miosis, and decreased facial sweating on the same side. Which structure is most likely compressed? Phrenic nerve Stellate ganglion Vagus nerve Optic chiasm Cervical sympathetic chain only below the diaphragm None Hint 157. A patient with portal hypertension develops large esophageal varices. Which portal venous tributary is involved in the portosystemic connection? Left gastric vein Inferior mesenteric vein Superior rectal vein only Splenic artery Right renal vein None Hint 158. A patient undergoes coronary artery bypass surgery using the left internal thoracic artery. Which coronary vessel is the usual target of this graft? Right coronary artery Left anterior descending artery Left circumflex artery Posterior descending artery only Left main artery only None Hint 159. After an elbow injury, a patient has weakness of thumb opposition and cannot make a normal 'OK' sign. Which nerve is most likely involved? Radial nerve Ulnar nerve Median nerve Axillary nerve Musculocutaneous nerve None Hint 160. A patient has a pelvic fracture with a Trendelenburg gait. Weakness of which movement most directly explains the gait? Hip extension Hip adduction Hip abduction Knee flexion Ankle dorsiflexion None Hint 161. During radical prostate surgery, preservation of which structure is particularly important for maintaining voluntary urinary continence? External urethral sphincter Seminal vesicles Internal urethral sphincter only Prostatic capsule only Ureteric orifice None Hint 162. A patient with a thoracic aortic aneurysm develops persistent hoarseness. Which nerve is most likely compressed? Right recurrent laryngeal nerve Left recurrent laryngeal nerve Right phrenic nerve Left vagus nerve only in the neck Hypoglossal nerve None Hint 163. A newborn has a lumbosacral mass containing neural tissue and meninges. Which embryologic error is responsible? Failure of posterior neural tube closure Failure of foregut rotation Failure of neural crest migration only Failure of anterior neuropore closure only Abnormal somite segmentation None Hint 164. A child has a midline neck mass that moves upward when he swallows and protrudes with tongue movement. Which embryologic remnant is most likely involved? Branchial cleft Thyroglossal duct Pyriform sinus Foramen ovale Omphalomesenteric duct None Hint 165. A newborn has severe respiratory distress and imaging reveals bowel loops within the left thorax with mediastinal shift. Which embryologic structure failed to close? Pleuroperitoneal membrane Tracheoesophageal septum Aorticopulmonary septum Septum transversum only Neural tube None Hint 166. A newborn repeatedly coughs and becomes cyanotic during feeding. Imaging shows a distal tracheoesophageal connection with esophageal interruption. Which embryologic process failed? Separation of foregut into trachea and esophagus Closure of the neural tube Fusion of palatal shelves Rotation of the midgut Descent of the thyroid None Hint 167. A newborn has cyanosis and an echocardiogram shows the aorta arising from the right ventricle and pulmonary artery from the left ventricle. Which developmental structure is abnormal? Aorticopulmonary septum Endocardial cushion only Septum transversum Neural crest of the pharynx only Ductus venosus None Hint 168. A newborn has a single arterial trunk overriding a large ventricular septal defect. Which embryologic structure failed to divide the outflow tract? Aorticopulmonary septum Septum primum Endocardial cushion only Interatrial septum Ductus arteriosus None Hint 169. A healthy adult loses approximately 1.5 L of isotonic fluid through severe sweating. Which compartment initially experiences the greatest volume loss? Intracellular fluid Extracellular fluid Both equally with no shift Transcellular fluid only Intravascular fluid exclusively None Hint 170. A patient with central diabetes insipidus produces very large volumes of dilute urine. Which hormone normally increases collecting-duct water permeability? Aldosterone ADH ANP Cortisol PTH None Hint 171. A patient with primary adrenal insufficiency has marked orthostatic hypotension. Which hormone deficiency most directly reduces sodium retention and extracellular volume? Cortisol Aldosterone Epinephrine ADH Growth hormone None Hint 172. During intense exercise, blood flow to active skeletal muscle increases despite sympathetic vasoconstrictor activity elsewhere. Which local mechanism is most important? Accumulation of vasodilating metabolites Increased plasma oncotic pressure Reduced local carbon dioxide Decreased adenosine Increased endothelin release None Hint 173. A healthy person rapidly ascends to high altitude and begins to hyperventilate. Which arterial change is the primary stimulus for the peripheral chemoreceptors? Increased PaO2 Decreased PaO2 Increased PaCO2 only Increased bicarbonate Decreased lactate None Hint 174. A patient with chronic obstructive pulmonary disease has a reduced FEV1/FVC ratio. Which physiologic abnormality is primarily responsible? Increased airway resistance Decreased airway resistance Increased lung compliance only Reduced residual volume Increased diffusion capacity None Hint 175. A 3-week-old infant has forceful projectile, nonbilious vomiting after feeds and an olive-shaped abdominal mass. Which acid-base disturbance is expected? High-anion-gap metabolic acidosis Hypochloremic metabolic alkalosis Respiratory alkalosis Normal acid-base status Hyperchloremic metabolic acidosis None Hint 176. A patient with advanced chronic kidney disease develops normocytic anemia despite adequate iron stores. Which hormone deficiency is most responsible? Erythropoietin Thrombopoietin Renin Hepcidin Calcitonin None Hint 177. A patient receives a loop diuretic and develops hypokalemia. Which renal effect contributes most directly to potassium loss? Reduced distal sodium delivery Increased distal sodium delivery and tubular flow Inhibition of aldosterone secretion Reduced urine flow Increased proximal potassium reabsorption only None Hint 178. A patient with systolic heart failure has an elevated plasma BNP concentration. Which cardiac stimulus most directly triggers BNP release? Myocardial wall stretch Low serum sodium alone Decreased atrial pressure Hypoglycemia Reduced venous return None Hint 179. A patient with chronic endogenous cortisol excess develops osteoporosis. Which mechanism contributes to the loss of bone mass? Increased osteoblast activity Reduced osteoclast activity Reduced osteoblast function with increased bone resorption Increased intestinal calcium absorption Increased calcitriol synthesis None Hint 180. A patient loses approximately 15% of blood volume after trauma. Which cardiovascular response occurs rapidly to help maintain arterial pressure? Decreased sympathetic tone Increased heart rate and systemic vasoconstriction Reduced renin release Increased vagal tone Decreased contractility None Hint 181. A patient with strict vegan dietary intake develops paresthesias, impaired vibration sense, and macrocytic anemia. Which vitamin deficiency is most likely? Folate Vitamin B12 Vitamin C Vitamin K Vitamin E None Hint 182. A patient with chronic alcohol use reports difficulty seeing in dim light. Which vitamin deficiency is most likely responsible? Vitamin A Vitamin B1 Vitamin B6 Vitamin B12 Vitamin K None Hint 183. A pregnant woman at 28 weeks has persistent hyperglycemia despite dietary counseling. Which fetal complication is most strongly associated with maternal hyperglycemia? Microsomia Macrosomia Neural tube defect only after 28 weeks Severe fetal hypothyroidism Congenital cataracts in all cases None Hint 184. A patient with HIV has multiple ring-enhancing brain lesions and a CD4 count below 100 cells/mm3. Which pathogen is most likely? Toxoplasma gondii Cryptococcus neoformans JC virus CMV only Listeria monocytogenes None Hint 185. A patient with rheumatoid arthritis begins methotrexate. Which supplement is commonly given to reduce mucosal and hematologic toxicity without eliminating the drug's therapeutic effect? Folic acid Vitamin K Vitamin A Niacin Thiamine None Hint 186. A patient with heart failure taking digoxin and furosemide develops nausea, visual changes, and ventricular ectopy. Which electrolyte abnormality increases digoxin toxicity? Hypernatremia Hypokalemia Hypermagnesemia Hypocalcemia Hypophosphatemia None Hint 187. A patient presents with an acutely swollen first metatarsophalangeal joint. Synovial fluid shows needle-shaped crystals with strong negative birefringence. What is the crystal? Calcium pyrophosphate Monosodium urate Basic calcium phosphate Calcium oxalate Cholesterol crystals None Hint 188. A patient with chronic hepatitis B develops hepatocellular carcinoma. Which viral protein contributes directly to oncogenic signaling and interference with tumor-suppressor pathways? HBsAg HBcAg HBx DNA polymerase HBeAg None Hint 189. A patient with ulcerative colitis has cholangiographic evidence of primary sclerosing cholangitis. Which antibody is commonly associated with this condition? Anti-mitochondrial antibody p-ANCA Anti-CCP Anti-dsDNA Anti-GBM antibody None Hint 190. A woman with a strong family history of breast and ovarian cancer undergoes genetic testing. Which inherited mutation is particularly associated with a high lifetime risk of ovarian carcinoma? BRCA1 APC RB1 RET NF1 None Hint 191. A child has recurrent viral and fungal infections, hypocalcemia, and a congenital cardiac anomaly. Chest radiography shows a markedly reduced thymic shadow. Which immune defect is most likely? Isolated B-cell deficiency T-cell deficiency Neutrophil oxidative-burst defect Complement C5 deficiency IgA deficiency None Hint 192. A patient with peanut allergy develops wheezing, hypotension, urticaria, and bronchospasm within minutes. Which mediator is a particularly potent cause of bronchoconstriction? Leukotrienes Nitric oxide Bradykinin Atrial natriuretic peptide Interferon-gamma None Hint 193. A young man with recurrent spontaneous hemarthroses has prolonged aPTT with a normal PT. Which clotting factor deficiency is most likely? Factor VII Factor VIII Factor V Factor XIII Fibrinogen None Hint 194. A patient with essential thrombocythemia develops painful red, burning toes caused by platelet-mediated microvascular occlusion. Which drug rapidly improves this symptom in many patients? Aspirin Warfarin Heparin Clopidogrel only after surgery Alteplase None Hint 195. A 68-year-old man with atrial fibrillation has hypertension and diabetes but no prior stroke. Which validated score is commonly used to estimate thromboembolic stroke risk? CHA2DS2-VASc APGAR Wells TIMI CURB-65 None Hint 196. A pregnant woman with poorly controlled gestational diabetes has a fetus measuring well above the expected size. Which fetal hormone most directly mediates the growth-promoting effect of maternal hyperglycemia? Fetal insulin Maternal insulin Maternal glucagon Fetal cortisol only Maternal growth hormone None Hint 197. A patient with advanced chronic kidney disease develops medial arterial calcification and a high calcium-phosphate product. Which abnormality is a major driver? Hyperphosphatemia Hypophosphatemia Hypernatremia Low uric acid Low chloride None Hint 198. A patient with long-standing type 1 diabetes develops burning pain and numbness in both feet in a stocking distribution. Which mechanism best explains the neuropathy? Microvascular ischemia and metabolic injury Direct bacterial invasion Acute demyelination only Compression of one peripheral nerve Excess acetylcholine release None Hint 199. A patient with Wilson disease has tremor, dysarthria, liver disease, and Kayser-Fleischer rings. Where does copper initially accumulate most importantly? Liver Heart Spleen Bone marrow Lung None Hint 200. A screening program identifies 90% of people who truly have a disease. Among healthy people, 15% receive a false-positive result. What are the sensitivity and specificity? Sensitivity 90%, specificity 85% Sensitivity 85%, specificity 90% Sensitivity 90%, specificity 15% Sensitivity 15%, specificity 90% Sensitivity 75%, specificity 90% None Hint 1 out of 100 Time's up
