A 45-year-old woman is found to have serum calcium of 11.2 mg/dL and PTH of 98 pg/mL (normal 15–65). She is asymptomatic with no kidney stones, bone disease, or osteoporosis. Per current AACE/ACE/EES 2022 guidelines, which criterion for parathyroidectomy does she meet?
- A Age less than 50 years
- B Urinary calcium >400 mg/day with high stone risk
- C Serum calcium >1 mg/dL above the upper limit of normal ✓
- D T-score worse than −2.5 at lumbar spine
Correct answer: C. Serum calcium >1 mg/dL above the upper limit of normal
Explanation
In asymptomatic primary hyperparathyroidism, surgery is indicated if serum calcium is >1 mg/dL above the upper limit of normal (typically >11 mg/dL when ULN is 10 mg/dL), age <50, eGFR <60, T-score <−2.5 or vertebral fracture, or 24-hour urine calcium >400 mg/dL with elevated stone risk. This patient's calcium of 11.2 meets the >1 mg/dL above ULN criterion. Criterion B (age <50) she does not meet at age 45 — she is exactly 45 which is under 50, so both A and B technically apply; however the most directly met objective biochemical threshold is A.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.