A 55-year-old woman is found to have a serum calcium of 10.9 mg/dL on routine testing. PTH is 82 pg/mL (elevated). She is asymptomatic. Her BMD shows T-score of −2.0 at lumbar spine. 24-hour urine calcium is 380 mg/day. eGFR is 68 mL/min. Which criterion for parathyroidectomy does she fulfil?
- A Serum calcium > 1 mg/dL above upper limit of normal ✓
- B 24-hour urine calcium > 400 mg/day
- C T-score worse than −2.5 at any site
- D eGFR < 60 mL/min
Explanation
The 2022 Fourth International Workshop guidelines for asymptomatic primary hyperparathyroidism recommend parathyroidectomy when serum calcium is > 1 mg/dL above the upper limit of normal (approximately > 11.0–11.5 mg/dL depending on lab reference); her level of 10.9 mg/dL is borderline but if ULN is 10.2, then 10.9 is > 1 mg/dL above. The other criteria are: BMD T-score ≤ −2.5 at any site or vertebral fracture by imaging; eGFR < 60 mL/min (not < 68); urinary calcium > 400 mg/day with elevated stone risk. Her T-score is −2.0 (not meeting the −2.5 threshold), urine calcium is 380 (not > 400), and eGFR is 68 (not < 60). The serum calcium criterion is the one she most nearly meets.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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