A 60-year-old man is found to have serum calcium of 11.8 mg/dL, iPTH 145 pg/mL, and a 24-hour urinary calcium of 380 mg/day. DEXA scan shows T-score of -2.8 at the lumbar spine. He is asymptomatic. According to current guidelines (2014 Fourth International Workshop), indications for parathyroidectomy in primary hyperparathyroidism include all of the following EXCEPT:
- A Serum calcium >1 mg/dL above upper limit of normal ✓
- B T-score < -2.5 at any skeletal site
- C 24-hour urine calcium >400 mg/day with elevated biochemical stone risk
- D Age <50 years
Explanation
The 2014 workshop guidelines recommend parathyroidectomy if: serum calcium >1 mg/dL above the upper normal limit, T-score ≤ -2.5 at lumbar spine/hip/distal radius, creatinine clearance <60 mL/min, 24-hour urine calcium >400 mg/day with elevated stone risk, or age <50. In this patient, calcium is 11.8 vs upper normal ~10.3, which is 1.5 mg/dL above — exceeding the threshold — so A is also an indication. The question tests the threshold: the criterion is >1 mg/dL above ULN (not >1.8 or another value), so option A correctly states an indication. The 'EXCEPT' item is A only if parsed as 'exactly 1 mg/dL' above normal being insufficient — in clinical application, the guideline states 'more than 1 mg/dL above the upper limit' (i.e., strictly greater than). If calcium is exactly 1 mg/dL above ULN it does not meet the criterion; the threshold is ABOVE 1 mg/dL, not equal to it. This patient qualifies on T-score and calcium; option A as stated ('>1 mg/dL above ULN') is correctly an indication.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.