Renal System MCAT Practice Question
A 58-year-old man with hypertension begins a new antihypertensive medication. After 2 weeks of therapy, he develops muscle cramps in his legs and episodes of palpitations. Serum electrolytes show sodium 138 mEq/L (normal 135–145), potassium 2.8 mEq/L (normal 3.5–5.0), magnesium 1.4 mg/dL (normal 1.7–2.2), and calcium 9.2 mg/dL (normal 8.5–10.5). The medication is later found to inhibit the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle. Which of the following best explains the patient's clinical presentation?
Answer choices
- AHyperkalemia causing cardiac dysrhythmia and muscle weakness
- BHypokalemia and hypomagnesemia causing muscle cramps and cardiac arrhythmiasCorrect answer
- CHypercalcemia and hyperphosphatemia causing muscle tetany and arrhythmias
- DHyponatremia causing cerebral edema and muscle cramps
- EHypomagnesemia alone causing all electrolyte-related symptoms
- FHypocalcemia and hypokalemia causing muscle cramps with preserved cardiac function
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