A 44-year-old woman presents with recurrent nephrolithiasis, serum calcium 11.4 mg/dL, phosphate 2.3 mg/dL, alkaline phosphatase 340 U/L, and PTH 98 pg/mL (elevated). DEXA shows Z-score −2.1 at the radius. She is otherwise asymptomatic. According to current guidelines, which criterion mandates parathyroidectomy in asymptomatic primary hyperparathyroidism?
- A Serum calcium > 1.0 mg/dL above upper limit of normal
- B T-score ≤ −2.5 or Z-score ≤ −2.5 at any site
- C Age < 50 years with any degree of hypercalcaemia
- D Presence of nephrolithiasis regardless of other parameters ✓
Explanation
Current guidelines (Fourth International Workshop on Asymptomatic Primary Hyperparathyroidism, 2014; updated 2022 consensus) classify radiologically confirmed nephrolithiasis or nephrocalcinosis as a mandatory surgical indication regardless of other parameters, because stones will recur and surgery is the only cure. Serum calcium > 1.0 mg/dL above ULN is also an indication but is listed as criterion A. Age < 50 is an indication for surgery but does not require any additional calcium threshold; densitometric criteria require T-score ≤ −2.5 (not Z-score) at any skeletal site, or fracture on vertebral imaging. Nephrolithiasis stands alone as a sufficiently compelling indication.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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