In primary hypoparathyroidism, the preferred long-term monitoring target for urine calcium excretion to avoid nephrocalcinosis while maintaining acceptable serum calcium is:
- A < 300 mg/24h (men) and < 250 mg/24h (women) ✓
- B < 400 mg/24h in all patients
- C Normal range for age regardless of level
- D < 500 mg/24h in patients on thiazide diuretics
Correct answer: A. < 300 mg/24h (men) and < 250 mg/24h (women)
Explanation
In chronic hypoparathyroidism managed with calcium and calcitriol, urinary calcium should be maintained below 300 mg/24h in men and 250 mg/24h in women — per Endocrine Society guidelines — to prevent nephrocalcinosis and nephrolithiasis while accepting a serum calcium in the low-normal range (2.0–2.25 mmol/L). Higher thresholds increase renal risk substantially. Thiazide diuretics reduce urinary calcium excretion and may allow higher serum calcium targets.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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