A 65-year-old man is found to have serum calcium of 11.6 mg/dL, PTH of 95 pg/mL (elevated), phosphate 2.4 mg/dL, and 24-hour urine calcium of 280 mg. Bone density shows T-score of –1.8 at lumbar spine. He is asymptomatic. Which criterion per 2022 guidelines mandates parathyroidectomy?
- A Serum calcium >1 mg/dL above upper limit of normal
- B 24-hour urine calcium >400 mg/day with increased stone risk ✓
- C T-score of –1.8 at lumbar spine
- D Age under 50 years
Explanation
The 2022 Fourth International Workshop on Asymptomatic Primary Hyperparathyroidism recommends parathyroidectomy when 24-hour urine calcium exceeds 400 mg/day AND there is an increased biochemical stone risk profile. Other criteria include: serum calcium >1 mg/dL above upper normal; eGFR <60; T-score ≤–2.5 or vertebral fracture; age <50 years. The T-score of –1.8 at the lumbar spine does NOT meet the threshold of –2.5, while age 65 does not trigger the age criterion. A serum calcium 11.6 mg/dL is typically ~1 mg/dL above normal (upper ~10.5), which is a borderline finding.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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