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Multisystem Processes & Disorders — Step 1 practice questions
170 questions in this area, with an explanation for every answer choice.
Three samples below, free and without an account.
How this shows up on Step 1
This section covers what does not sit in one organ: shock, sepsis, poisoning, nutritional deficiency, and the genetic syndromes that touch several systems at once. Questions often require holding two systems in mind simultaneously, which is what makes them feel harder than their content warrants.
Sample questions
Sample question 1
A patient has hyperextensible, fragile skin, joint hypermobility, and easy bruising, with a defect in collagen synthesis. Which of the following is the most likely diagnosis?
Explanations
A. Marfan syndrome
Marfan syndrome results from a FIBRILLIN (not primarily collagen) defect, causing a different phenotype (tall stature, lens dislocation, aortic dilation) without this classic skin hyperextensibility/fragility pattern.
B. Osteogenesis imperfecta exclusively
Osteogenesis imperfecta also involves collagen defects but primarily manifests as bone fragility/fractures, not primarily this skin hyperextensibility pattern.
C. Down syndrome
Down syndrome is a chromosomal trisomy, unrelated to this collagen defect presentation.
D. Klinefelter syndrome
Klinefelter syndrome is a sex chromosome abnormality, unrelated to this collagen defect presentation.
E. Ehlers-Danlos syndrome · correct
Ehlers-Danlos syndrome, resulting from various collagen synthesis/structure defects, classically causes hyperextensible fragile skin, joint hypermobility, and easy bruising/poor wound healing.
Sample question 2
A patient with small cell lung carcinoma develops hyponatremia with concentrated urine and euvolemia. Which of the following best describes this and other paraneoplastic associations?
Explanations
A. Hypercalcemia of malignancy results from elevated true PTH
True PTH is suppressed; PTHrP mediates the hypercalcemia.
B. Ectopic PTH secretion causing hyponatremia
Ectopic PTH-related peptide causes hypercalcemia rather than hyponatremia.
C. Ectopic ADH production causing SIADH, alongside other associations such as ectopic ACTH with small cell carcinoma and PTH-related peptide with squamous cell carcinoma · correct
Paraneoplastic syndromes result from tumor-derived hormones or immune cross-reactivity rather than mass effect or metastasis, and may PRECEDE the cancer diagnosis. SMALL CELL lung carcinoma, of neuroendocrine origin, classically causes SIADH from ectopic ADH and Cushing syndrome from ectopic ACTH, plus Lambert-Eaton syndrome. SQUAMOUS cell carcinoma classically causes hypercalcemia via PTH-RELATED PEPTIDE — which acts at the PTH receptor while true PTH is SUPPRESSED, the key laboratory distinction from primary hyperparathyroidism. Renal cell carcinoma can secrete erythropoietin causing erythrocytosis.
D. Paraneoplastic syndromes only occur with metastatic disease
They occur with localized disease and may precede diagnosis.
E. Squamous cell carcinoma is the classic cause of SIADH
Small cell carcinoma is the classic SIADH association.
Sample question 3
An 80-year-old develops a serious bacterial infection without fever or leukocytosis. Which of the following best explains this presentation?
Explanations
A. Older adults have increased vaccine responsiveness
Vaccine responses are diminished.
B. Immunosenescence with blunted febrile and inflammatory responses, so older adults often present atypically with delirium, falls, or functional decline rather than classic signs · correct
IMMUNOSENESCENCE encompasses thymic involution with fewer naive T cells, reduced antibody affinity and vaccine response, and blunted febrile and inflammatory responses — so up to a third of older adults with serious infection lack fever or leukocytosis. Presentation is instead ATYPICAL: delirium, falls, functional decline, anorexia, or generalized weakness may be the only manifestations of pneumonia or urinary infection. Recognizing this prevents dangerous delays, and it explains why higher-dose and adjuvanted vaccines are used in this population.
C. Immune function is unchanged with aging
Substantial immune changes accompany aging.
D. The absence of fever reliably excludes infection at any age
Absence of fever does not exclude serious infection in older adults.
E. Older adults mount exaggerated inflammatory responses to infection
Inflammatory responses are blunted, though baseline low-grade inflammation ("inflammaging") is increased.
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