Electrolyte Disorders USMLE Step 1 Practice Question
A 38-year-old man with acute pancreatitis presents with circumoral paresthesias and tetany. Vital signs show BP 128/82 mmHg, HR 102 bpm, RR 20/min, temperature 38.2°C, SpO2 98% on room air. Laboratory studies reveal ionized calcium 6.8 mg/dL with albumin 3.2 g/dL, phosphate 8.2 mg/dL, magnesium 1.4 mEq/L, and normal creatinine 0.9 mg/dL. Electrocardiogram shows normal QT interval. Which mechanism primarily explains the hypocalcemia?
Answer choices
- AHypomagnesemia reducing PTH secretion and peripheral PTH resistanceCorrect answer
- BAcute kidney injury with hyperphosphatemia and tertiary hyperparathyroidism
- CSaponification of dietary fat consuming circulating calcium
- DVitamin D deficiency from malabsorption in acute illness
- EHemodilution from aggressive fluid resuscitation
- FSaponification of peripancreatic fat consuming calcium
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