A 32-year-old man has serum calcium 11.4 mg/dL and PTH 78 pg/mL on routine testing. His father and sister have similar biochemistry but none has had stones, fractures or peptic ulceration. A sestamibi scan is negative. Twenty-four hour urinary calcium is low. Urinary calcium to creatinine clearance ratio is 0.005. The correct management is:
- A Focused parathyroidectomy guided by four-dimensional CT
- B No surgery, genetic counselling regarding CASR mutation, and reassurance ✓
- C Four-gland exploration with subtotal parathyroidectomy
- D Cinacalcet therapy titrated to normalize serum calcium
Correct answer: B. No surgery, genetic counselling regarding CASR mutation, and reassurance
Explanation
B urinary calcium to creatinine clearance ratio below 0.01 with mild hypercalcaemia, inappropriately detectable PTH, a negative localising study and a compatible family history defines familial hypocalciuric hypercalcaemia, caused by an inactivating CASR mutation inherited autosomal dominantly. It is benign, needs no parathyroid surgery, and removing glands in such patients does not cure the calcium level and risks permanent hypoparathyroidism. Cinacalcet is reserved for symptomatic exceptions, not routine care.
Reference: Williams Textbook of Endocrinology, 14th ed.
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Written and medically reviewed by the StethoPrep medical team.