The Complete Free 120 Master Guide.

Prevalence Swap. All options cause VTE; NBME forces you to pick the most common inherited cause without giving you a direct frequency clue.

Antibody lineup. Multiple real antibody tests offered; must know anti-CCP is the most specific for RA, not just associated.

Level confusion. All wrong answers are real cranial nerve deficits, but each belongs to a different brainstem level. NBME tests whether you know which structures co-localize.

Negative Monospot anchor. Most students eliminate HIV because they default to EBV for mononucleosis-like illness. The negative heterophile antibody is the pivot that forces you away from EBV.

AKI type identification. Multiple causes of AKI are offered; the urinalysis (WBC casts + eosinophils) is the definitive clue that places this in the interstitium, not the glomerulus or tubule.

Chiari vs trauma misdirect. The clinical picture (headache + syrinx) could suggest Chiari I, but the question asks what history to obtain, and trauma is the most common acquired cause that a patient would not volunteer.

Vasculitis vs atherosclerosis. Several options describe real vascular pathologies; must match the demographic (older diabetic male with multiple CV risk factors) to the correct mechanism.

Righting reflex. Physicians instinctively want to give advice or guilt-trip the patient into changing. NBME tests whether you recognize the non-confrontational, exploratory approach of MI.

Weight-height discordance. Weight falling off while height is maintained means something is consuming calories without affecting linear growth. Organic causes typically affect both; caloric insufficiency hits weight first.

Reliability vs validity confusion. Students confuse internal reliability (consistency) with internal validity (accuracy of measurement). Adding a food item doesn't change consistency; it changes completeness of measurement.

Latin America + immigration → Chagas should fire immediately, but students who don't know the reduviid bug will guess mosquito (too familiar).

The urge to educate or convince. Most wrong answers either push medication or express frustration. The correct answer explores what the patient actually wants from the visit.

Alpha/beta + agonist/antagonist matrix. Four possible combinations on alpha, four on beta. Must know BPH uses alpha-1 antagonism specifically, not just "alpha blocker."

Schizophrenia anchoring. The presence of hallucinations and delusions makes students immediately think schizophrenia. The manic features (decreased sleep, pressured speech, grandiosity, goal-directed behavior) are the discriminating elements.

Curve ranking without mechanistic anchor. If you just guess which curve looks "bigger," you might pick the right answer accidentally, but NBME wants you to know WHY the PPI produces a higher, more sustained curve than the H2 blocker.

Pulmonary vein misdirect. The pulmonary vein sounds like it should connect lungs to metastasis, but it carries oxygenated blood FROM the lungs BACK to the heart. It cannot carry tumor emboli TO the lungs.

Serpiginous tracks in webspaces are so distinctive for scabies that this is a pattern recognition question, but students who don't know this description will guess chickenpox or Lyme by process of elimination.

Fatty food trigger misdirect. Students anchor on the meal and jump to cholesterol stones. The underlying sickle cell disease is the essential context that changes the stone type entirely.

MEN1 vs MEN2 gene type confusion. MEN1 uses a tumor suppressor (MEN1 gene), MEN2 uses a proto-oncogene (RET). Students who know the wrong MEN syndrome will pick tumor suppressor.

LH misread. This was the critical lab error in the original guide. LH is 3.0 mIU/mL against a normal of <0.2. It is 15 times the upper limit of normal. Peripheral precocious puberty (the alternative) requires SUPPRESSED LH.

High FSH/LH in a teenage boy signals primary gonadal failure. The axis is trying but the gonads aren't responding. The phenotype (tall, gynecomastia, small testes) plus this hormonal pattern = Klinefelter.

The electrolytes tell the story. Hyponatremia + hyperkalemia + metabolic acidosis in a newborn with ambiguous genitalia = CAH with aldosterone deficiency → treat with mineralocorticoid targeting the aldosterone receptor.

All options might theoretically be managed eventually, but NBME tests which complication of uremia cannot wait and requires same-day dialysis. Pericardial friction rub = uremic pericarditis = emergency.

Preload vs contractility confusion. Acute MI drops CONTRACTILITY (ESPVR shifts down), not preload. The transition must show a downward shift of the operating point, not movement along the same curve.

Decarboxylase anchoring. Carbidopa already inhibits aromatic L-amino acid decarboxylase. Adding another AADC inhibitor does nothing. The adjunct must target a DIFFERENT enzyme in the dopamine metabolism pathway.

CT scan interpretation + anatomical position. Left posterior 10th intercostal space is below the diaphragm on the left. The large homogeneous left-sided organ in the upper abdomen posterior to the stomach is the spleen.

Psychiatric patient + fever + antipsychotic = NMS until proven otherwise. The combination of olanzapine initiation + fever + rigidity (not hyperreflexia) is the specific pattern.

The pelvicalyceal location (NOT renal parenchyma) + occupational exposure to naphthylamine + smoking history points to urothelial (transitional cell) carcinoma, not renal cell carcinoma.

Type 1 DM anchor. The diabetes is there to distract. The rash description (episodic, stress-triggered, facial flushing/redness, burning) is classic rosacea, and the most important additional history for rosacea is alcohol trigger.

Herd immunity vs eradication. Community eradication means the disease is gone from that area completely; herd immunity means enough people are vaccinated that transmission chains break even for unvaccinated individuals. These are different concepts and only one applies here.

Anti-D IgG binding target confusion. RhoGAM works by binding to Rh-positive fetal red cells that have entered maternal circulation, preventing maternal sensitization. It does NOT block complement or change class switching.

The pathway must be one that produces URIC ACID as an end product. Uric acid is the final breakdown product of purines. Only the purine degradation pathway directly generates uric acid.

The patient has not identified alcohol as a problem. She mentioned the DUI incidentally. The physician's first response should be open-ended and non-confrontational to understand her perspective before screening or advising.

Lymphatics from mesoderm is the answer, but the specific mechanism (budding from veins, mesodermal origin) is less known than the other germ layer associations.

Obese + hypercapnic + hypoxic = OHS. The question asks what ELSE would be found. Must reason from the physiology of chronic hypercapnia and hypoxia.

The triad of microangiopathic hemolytic anemia + thrombocytopenia + renal failure in a child after bloody diarrhea = HUS = Shiga toxin-producing E. Coli O157:H7.

Hyperplasia vs hypertrophy. Cardiac myocytes are terminally differentiated and cannot divide. LVH is from hypertrophy (increased protein synthesis in existing cells), not hyperplasia.

Metabolic activation. Carcinogens are often pro-carcinogens that require enzymatic conversion to electrophilic intermediates. CYP450 enzymes perform this activation. Other enzymes listed either detoxify or are unrelated.

Phase 1 = first in humans + healthy volunteers + safety/pharmacokinetics. The keywords: "healthy volunteers" + "maximum tolerated dose" + "pharmacokinetic properties" define Phase 1 unambiguously.

Glucagon works by stimulating hepatic GLYCOGENOLYSIS. If there's no glycogen to mobilize, glucagon can't raise glucose. Endurance exercise depletes hepatic glycogen stores.

Transparency calibration. The radiologist suspects cancer but hasn't confirmed it. The physician must be honest about concern without stating an unconfirmed diagnosis as fact.

Elevated hemoglobin + thrombocytosis + splenomegaly in a non-smoking, non-hypoxic patient = polycythemia vera = JAK2 V617F mutation.

Olfactory aura = uncus = temporal lobe medial surface. The seizure type is complex partial with automatisms, originating from the mesial temporal lobe.

The finding that clinches the diagnosis is the combination of: bilateral parotid swelling + dental erosions + hand scarring (Russell's sign) = bulimia + oral thrush from fluoxetine-induced immunosuppression and altered oral flora.

Delayed onset (1 day after exposure) + contact with a plant antigen = Type IV (T cell-mediated, delayed) hypersensitivity. Any reaction that develops over 24-72 hours after antigen contact and involves T cells is Type IV.

Chronic hypoxia → pulmonary vasoconstriction → pulmonary hypertension → right heart failure. The question asks what DECREASED. RV diastolic compliance decreases as the RV becomes stiff from pressure overload.

Upper extremity hypertension + lower extremity hypotension + systolic murmur at the back + left sternal border = coarctation of the aorta. The additional finding is delayed femoral pulses (radio-femoral delay).

Suppressed PTH + hypercalcemia + bilateral hilar lymphadenopathy + interstitial infiltrates = sarcoidosis. The mechanism is 1-alpha-hydroxylase in granuloma macrophages converting 25-OH vitamin D to calcitriol (1,25-OH2 D3).

Oily, foul-smelling stools + weight loss + recurrent pancreatitis = exocrine pancreatic insufficiency = fat malabsorption = lipase deficiency is the primary therapeutic target.

Metronidazole treats invasive disease (liver abscess, amebic colitis), but does NOT eradicate the intestinal cyst form. Paromomycin is a luminal agent that eliminates the intestinal reservoir.

Orbital mass + malignant cells with striations in a 3-year-old = rhabdomyosarcoma. Striations = skeletal muscle origin. Orbital RMS is the most common pediatric orbital malignancy.

Puncture wound from wood + rapidly progressing infection with necrosis + systemic sepsis → Staphylococcus aureus is the most common cause of soft tissue infections from skin flora colonization of puncture wounds.

The key is identifying the HIGHEST level affected. Upper extremity LMN signs (atrophy, weakness 3/5) + lower extremity UMN signs + sensory level at clavicle = lesion at C5 level? No. The LMN findings in the HANDS with UPPER extremity involvement and NORMAL biceps/triceps reflex places it at C8/T1 (intrinsic hand muscles). But the sensory level at the clavicle = C4-ish. Wait. The question says DECREASED reflexes at biceps and triceps (which are C5/C6 and C7 respectively) but INCREASED at knees and ankles. This means the lesion must be above the knee but affecting the hand. Normal biceps (C5/C6) + normal triceps (C7) + weakness in HANDS (intrinsic muscles = C8/T1) + UMN in legs → lesion at C8-T1. But wait, the question says DTRs are NORMAL at biceps and triceps. So the lesion is below C7 but above T1. The sensory level "at and below the clavicle" = approximately C4-C5 level. This question is actually about a CENTRAL CORD syndrome or a specific lesion. Let me re-read: weakness of BOTH HANDS + atrophy of INTRINSIC HAND MUSCLES + weakness + increased tone in lower extremities + increased DTRs at knees/ankles + Babinski bilateral + sensation absent at and below clavicles. The clavicle is at approximately C4-C5 level. Normal biceps (C5/C6) and triceps (C7) but weakness and atrophy of intrinsic hand muscles (C8/T1). This is a CENTRAL CORD SYNDROME or lesion at C7-C8 level. The answer is C7 based on the hand muscle involvement with the sensory level being just below the hands.

Obese patient with exertional dyspnea + preserved O2 sat = pure restrictive pattern from abdominal fat restricting chest wall excursion. FEV1/FVC ratio is NORMAL or elevated (preserved), total lung capacity decreased, DLCO normal.

Postmenopausal + decreased libido + sexual activity present → think vaginal atrophy (genitourinary syndrome of menopause). Estrogen loss → vaginal epithelial thinning → loss of rugation.

The patient says "I hope that's okay. I haven't been able to get it lower". This is an expression of struggle and possible shame. The correct response explores her understanding and experience before lecturing or problem-solving.

Increasing sample size increases POWER (decreases type II error = beta). It does not change the type I error rate (alpha), which is set by the researcher, not by sample size.

The MRI shows hydronephrosis of the ENTIRE collecting system (renal pelvis dilated) without ureteral dilation described below a specific point. This localizes to the ureteropelvic junction (UPJ), the most common site of UPJ obstruction.

MAC is an opportunistic pathogen that only causes disseminated disease in profound immunodeficiency. In an HIV-negative child with MAC osteomyelitis, the specific defect is in the IL-12/IFN-gamma axis. The major pathway for macrophage activation against intracellular organisms.

Spindle cells at a biopsy site with interlacing fascicles and collagen = myofibroblastic proliferation = desmoid tumor/fibromatosis. Myofibroblasts are the cells responsible for wound contraction and, when dysregulated, for desmoid tumors.

ACE inhibitors are contraindicated in pregnancy (especially 2nd/3rd trimester) because they reduce fetal renal perfusion → oligohydramnios → fetal compression → Potter sequence features.

The autopsy image shows pink proteinaceous material filling alveolar spaces with congested capillaries. Pulmonary edema from a massive acute MI causing acute left heart failure.

Rifampin is the strongest CYP enzyme inducer in clinical medicine. Induction of CYP2C9 accelerates S-warfarin metabolism → decreased warfarin levels → subtherapeutic INR despite doubled dose.

AMD's strongest modifiable risk factor is smoking. Its strongest non-modifiable risk factor is age. Among ALL factors listed, age is the single greatest risk factor for AMD.

Chemotherapy causes neutropenia. A febrile neutropenic patient growing gram-negative rods is the classic leukemia-related immunocompromise scenario. The mechanism is neutropenia from myelosuppression.

ARR = Risk in control group - Risk in treatment group. Simple subtraction of the event rates. Do not multiply by enrollment rate (85%). That is a participation rate, not a probability modifier for the outcome.

The smear shows large monocytoid cells. High monocyte count (50%) + high lymphocytes (40%) with blasts in context of age, smoking, and acute presentation = AML M5 (acute monocytic leukemia). The photomicrograph shows myeloid blasts with monocytic differentiation.

Young patient + very high LDL + tendinous xanthomas + family history of premature MI = familial hypercholesterolemia = LDL receptor deficiency (autosomal dominant).

Key word: NEVER achieved full bladder control at night, but achieved daytime continence. This is primary enuresis = developmental delay in nocturnal detrusor/sphincter control. Normal exam + normal UA + no structural findings = maturational delay.

Hard, pebble-like stools + rectal prolapse + 5-year-old + constipation = simple constipation-driven rectal prolapse. This is common in children with straining. The rectal prolapse reduced here is the pink mucosal tissue protruding.

Autosomal recessive: parents must both be carriers (Aa × Aa). Offspring probabilities: 1/4 AA, 2/4 Aa, 1/4 aa. Since this woman (III-5) is UNAFFECTED, she cannot be aa. Of the remaining 3/4, 2 are carriers (Aa). So 2/3 of unaffected offspring are carriers.

The patient has hypotension + tachycardia. Need to raise BP. A beta agonist would raise HR further. A pure alpha agonist raises BP by vasoconstriction WITHOUT affecting HR (or may reflexively lower it via baroreceptor response).

Horseshoe kidney = fusion of the INFERIOR poles of the two metanephric kidneys during their ascent through the pelvis. As they ascend, the inferior poles get trapped under the inferior mesenteric artery.

This question tests the therapeutic alliance with adolescents. Expressing warmth and non-judgment FIRST creates the environment for honest disclosure. Clinical questions come second.

Obesity → increased insulin resistance → compensatory hyperinsulinemia to maintain euglycemia. Fasting insulin is elevated even before fasting glucose becomes truly diabetic.

Episodes triggered by carbohydrate/salt loading + strenuous exercise → hypokalemic periodic paralysis from CACNA1S or SCN4A mutation → K+ shifts intracellularly during recovery from exercise.

Low urine osmolality + responds to exogenous ADH → central DI = ADH is not being produced. The defect is in ADH production (supraoptic nucleus) or release, not in renal responsiveness (nephrogenic DI) or renal tubule function.

Round cells with clear cytoplasm + prominent nucleus in a young man with a painless testicular mass = seminoma. The most common testicular germ cell tumor.

Maternal alcohol (ethanol) = fetal alcohol spectrum disorder. The cardinal features include short palpebral fissures, smooth philtrum, thin upper lip, and cognitive/behavioral effects. Short palpebral fissures are the most specific facial feature.

New mother + hyperthyroid symptoms + enlarged nontender thyroid + undetectable TSH + NO exophthalmos + low radioactive iodine uptake → postpartum thyroiditis (lymphocytic thyroiditis). Mechanism = lymphocytic infiltration of the thyroid from rebound immune activity after pregnancy-induced immune suppression.

Specificity = TN/(TN+FP). With 1000 non-diseased people and 90% specificity → 100 false positives. The question asks about non-diseased people only.

Right parietal lobe → left visual field defect (lower quadrantanopia from Meyer's loop involvement) + left hemisensory neglect (extinction on double simultaneous stimulation). But NO motor deficit, NO language deficit.

Cardiac + hypocalcemia (from absent parathyroids) + T cell deficiency (from absent thymus) = DiGeorge syndrome = 22q11.2 deletion.

Irregular rhythm with no P waves + narrow QRS + binge alcohol → atrial fibrillation from holiday heart syndrome = right atrium (AF originates in atrial tissue, primarily around pulmonary veins entering left atrium, but the question may frame it as right atrial in the context of the conducting tissue).

NSAIDs inhibit COX-1 → decreased PGE2 and PGI2 → loss of gastric mucosal protection (decreased mucus, decreased bicarbonate, decreased blood flow) → ulceration and GI bleed.

Oligohydramnios → mechanical compression of fetus → clubfoot from external force on a normally formed limb = DEFORMATION. The intrinsic limb anatomy is normal; the external environment compressed it.

Tension pneumothorax = air accumulating under pressure in pleural space → ipsilateral lung collapse + mediastinal shift → decreased breath sounds + hyperresonance IPSILATERALLY + tracheal deviation AWAY from affected side + hemodynamic collapse.

10 days after blood loss → bone marrow has responded with reticulocyte release → polychromasia on Wright-Giemsa stain (reticulocytes appear blue-purple because residual RNA stains basophilically).

Floating oily stools + dry scaly skin + fat malabsorption setting = fat-soluble vitamin deficiency. Among fat-soluble vitamins, vitamin A deficiency specifically causes follicular hyperkeratosis and dry scaly skin (not just night blindness).

The renal medulla is naturally hypoxic AND hyperosmolar AND acidic. These three conditions are exactly what promote HbS polymerization and sickling. Papillary necrosis from sickling is therefore unique to the medulla.

Neutrophil chemotaxis in acute inflammation is primarily driven by leukotriene B4 (LTB4), complement fragment C5a, and IL-8. Of these, LTB4 is the major lipid chemotactic agent.

Psychosis onset within hours to days after a major stressor + duration < 1 month = brief psychotic disorder. The school shooting is the precipitating stressor.

Summer + children + aseptic meningitis cluster = enteroviral meningitis. Enteroviruses (echovirus, coxsackievirus) peak in summer and fall, spread fecal-oral, and cause the vast majority of viral meningitis cases.

FEV1/FVC = 1.0 (preserved) + reduced TLC + normal DLCO + hypercapnia → pure extrapulmonary restrictive disease from NEUROMUSCULAR WEAKNESS. The alveoli are structurally intact (normal DLCO) but the respiratory muscles can't expand the chest adequately.

Primary dysmenorrhea = uterine contractions from prostaglandin (PGF2α and PGE2) excess → painful menses. NSAIDs inhibit COX → decrease prostaglandin synthesis → reduce uterine contractions. This is the correct mechanism.

Dehydration → increased plasma osmolality → ADH release → ADH binds V2 receptors in collecting duct → cAMP → PKA → phosphorylation and insertion of AQUAPORIN-2 channels into apical membrane → water reabsorption.

Parotid gland swelling (parotitis) + college student + unvaccinated = mumps virus. Mumps is the classic cause of viral parotitis.

Ipilimumab is the prototypical anti-CTLA-4 antibody. CTLA-4 on T cells normally competes with CD28 for B7 ligand on APCs. CTLA-4 sends an inhibitory signal. Blocking CTLA-4 allows CD28 to activate T cells unopposed.

The patient's husband should NOT be the interpreter for serious medical conversations. Family members have conflicts of interest, may filter information, and remove the patient's autonomy. A professional medical interpreter (in person or via phone) is required.

Bordetella pertussis = whooping cough = macrolide antibiotic (azithromycin is first line, erythromycin second line). Treatment reduces contagiousness but may not shorten illness duration if started in the catarrhal phase.

Amphetamines are NOT simple reuptake inhibitors (like cocaine). They actively cause RELEASE of stored catecholamines from the terminal, specifically by reversing the monoamine transporter and displacing vesicular stores.

Tall young man + aortic regurgitation + back pain + hypotension = aortic root dissection from cystic medial necrosis of the aorta in Marfan syndrome. The aortic valve leaflets are anatomically normal. The regurgitation is from stretched aortic annulus/root.

Small cell lung cancer + proximal weakness that IMPROVES with repetitive stimulation + low amplitude compound motor action potential (CMAP) that INCREASES with high-frequency stimulation = Lambert-Eaton myasthenic syndrome (LEMS) = presynaptic calcium channel antibodies (VGCC-Ab).

CaSR normally senses Ca2+ and when activated, tells the parathyroid to STOP making PTH and tells the kidney to EXCRETE Ca2+. Inactivating CaSR mutation → parathyroid "thinks" Ca2+ is low → continues making PTH → elevated Ca2+. Kidneys also "think" Ca2+ is low → reabsorb Ca2+ instead of excreting → hypocalciuria.

Patient declining thoracenteses → physician should explore what she wants from the remaining time (goals of care conversation). Not override, not push, not abandon.

Phallic structure + urethral opening at base + vagina present = virilized genetic female from excess androgen exposure during development. Normal female internal anatomy (mullerian structures present) = Y chromosome absent = 46,XX.

Terbinafine inhibits squalene monooxygenase (squalene epoxidase) → squalene accumulates (toxic) → ergosterol depleted → fungal cell membrane disruption. This is distinct from azoles, which inhibit a LATER step (lanosterol 14-alpha demethylase).

Left eye fails to adduct on rightward gaze = left internuclear ophthalmoplegia = LEFT medial longitudinal fasciculus (MLF) lesion. The MLF connects CN VI nucleus on one side to CN III nucleus on the other side to coordinate conjugate gaze.