Home › Certifications › USMLE Step 1 › Multisystem Processes & Disorders
10 multiple-choice questions and 11 flashcards on Multisystem Processes & Disorders, about 6% of the USMLE Step 1 bank. Every one carries a written rationale.
Multisystem Processes & Disorders is one of 10 chapters in CoStudy's USMLE Step 1 — Medical Licensing bank, and it holds 10 of the bank's 172 multiple-choice questions — roughly 6% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
5 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
A patient on long-term, high-dose corticosteroids should be monitored for:
Answer: C — Osteoporosis, hyperglycemia, weight gain, immunosuppression, cataracts, mood changes, and adrenal suppression upon withdrawal
C) Classic glucocorticoid toxicity. A/B/D) Each contradicts known effects.
Streptococcus pyogenes (group A strep) infection of the throat carries the risk of which non-suppurative sequela 2–3 weeks later?
Answer: B — Acute rheumatic fever and post-streptococcal glomerulonephritis
GAS pharyngitis can trigger antibody cross-reactivity: ARF (heart, joints, brain, skin) and PSGN (kidneys). Treat with penicillin/amoxicillin to prevent ARF.
A 70-year-old man is admitted with pneumonia. Two days later he develops fever 39.5°C, heart rate 125/min, respiratory rate 26/min, and blood pressure 78/45 mmHg despite 30 mL/kg IV fluid resuscitation. Serum lactate is 4.5 mmol/L. Which term MOST precisely describes his current condition?
Answer: C — Septic shock (sepsis with persistent hypotension requiring vasopressors and elevated lactate despite adequate fluid resuscitation)
C) Correct: persistent hypotension (requiring vasopressor support to maintain MAP ≥65) and serum lactate >2 mmol/L DESPITE adequate fluid resuscitation defines septic shock per Sepsis-3 criteria — the most severe, precisely applicable term here given fluid-refractory hypotension and hyperlactatemia. B) 'Sepsis' (life-threatening organ dysfunction from dysregulated host response to infection, e.g., SOFA score increase ≥2) is present but is a less precise/complete answer once fluid-refractory hypotension with hyperlactatemia has developed — this patient has progressed beyond sepsis to septic shock, a half-right trap of choosing an earlier, still-true stage. A) SIRS criteria (temperature, heart rate, respiratory rate, WBC) are nonspecific and no longer the primary diagnostic framework in Sepsis-3; this vignette clearly exceeds SIRS with organ dysfunction and shock. D) Bacteremia refers only to viable bacteria in blood, not the clinical syndrome described. E) The patient DOES have shock (persistent hypotension), so this option is factually incorrect.
A 50-year-old man presents with sinusitis, hemoptysis, and hematuria. Chest imaging shows cavitary nodules, and renal biopsy shows pauci-immune crescentic glomerulonephritis. Serology is positive for c-ANCA (anti-proteinase 3). Which is the MOST likely diagnosis?
Answer: C — Granulomatosis with polyangiitis (formerly Wegener)
C) Correct: the classic triad of upper respiratory tract involvement (sinusitis), lower respiratory tract cavitary nodules, and pauci-immune (few/no immune deposits) crescentic glomerulonephritis with c-ANCA/PR3 positivity defines granulomatosis with polyangiitis. A) Microscopic polyangiitis also causes pauci-immune GN and pulmonary hemorrhage but is p-ANCA/MPO-positive and classically SPARES the upper airway/granuloma formation — off-by-one ANCA-vasculitis trap. B) Goodpasture (anti-GBM) causes pulmonary-renal syndrome via LINEAR anti-GBM antibody deposition, not ANCA positivity or granulomas. D) EGPA (Churg-Strauss) is associated with asthma, eosinophilia, and p-ANCA, not the upper-airway/cavitary-nodule/c-ANCA pattern. E) PAN is a medium-vessel vasculitis, typically ANCA-negative, sparing the lungs and glomeruli (favors renal arteries, causing microaneurysms, not GN).
A 25-year-old man is stung by a bee and within minutes develops diffuse urticaria, lip swelling, wheezing, and hypotension (BP 70/40). Which is the MOST appropriate FIRST-line treatment?
Answer: B — Intramuscular epinephrine (anterolateral thigh)
B) Correct: anaphylaxis (multi-system, rapid-onset IgE-mediated reaction with hypotension/airway compromise) requires IMMEDIATE intramuscular epinephrine in the anterolateral thigh as first-line therapy — it reverses vasodilation, bronchoconstriction, and mediator release; delay increases mortality. A) Antihistamines address urticaria/itching but do NOT reverse hypotension or airway compromise — an inadequate 'partial treatment' trap if given as the sole/first agent. C) Corticosteroids help prevent biphasic reactions but have delayed onset and are adjunctive, not first-line for the acute event. D) Albuterol helps bronchospasm but doesn't address hypotension or the systemic mediator cascade; adjunctive only. E) IV fluids are important for hypotension but epinephrine remains first-line and should not be delayed for fluids alone.
4 cards from the 11 in this chapter.
NPV?
TN / (TN + FN). Probability of no disease given negative test.
Four ethical principles?
Autonomy, beneficence, non-maleficence, justice.
Tumor staging vs grading?
Staging: extent of spread (TNM). Grading: histologic appearance.
PPV?
TP / (TP + FP). Probability of disease given positive test.
These are a sample. The full Multisystem Processes & Disorders chapter runs 21 items with per-chapter progress tracking, on the web and in the iOS app.
Open USMLE Step 1 in CoStudy →