A 45-year-old woman with familial hypocalciuric hypercalcaemia (FHH) is referred for consideration of parathyroidectomy. Why is parathyroidectomy NOT indicated in FHH?

• A FHH causes hypercalcaemia due to overactive parathyroid glands that will recur after subtotal resection
• B FHH resolves spontaneously after menopause and surgery should be deferred
• C FHH is associated with severe osteoporosis and surgery risks pathological fractures
• D FHH is caused by a loss-of-function mutation in the calcium-sensing receptor (CaSR), causing high renal calcium reabsorption; parathyroid glands are normal and surgery does not correct the defect ✓

Explanation

Familial hypocalciuric hypercalcaemia (FHH) is caused by a heterozygous loss-of-function mutation in the CaSR gene (chromosome 3q21), leading to reduced calcium sensing, resetting of the calcium set-point, and increased renal tubular calcium reabsorption (low urinary calcium — Ca:creatinine clearance ratio <0.01 distinguishes FHH from primary hyperparathyroidism). The parathyroid glands are normal or mildly hyperplastic but not primarily diseased; parathyroidectomy does not correct the renal reabsorption defect and results in persistent hypercalcaemia. FHH is a benign condition requiring no treatment.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.