Hypoparathyroidism in Wilson's disease.

An 11-year-old girl with Wilson's disease presented with mild hypocalcemia (8.0 mg per deciliter), hypophosphatemia (2.7 mg per deciliter), hypercalciuria (569 mg per day), and hyperphosphaturia (tubular reabsorption of phosphate, 67 per cent). The hyperphosphaturia and hypercalciuria were attributed to the Fanconi syndrome, a known component of Wilson's disease. Circulating immunoreactive parathyroid hormone was usually undetectable or, occasionally, detectable at minimal levels in the presence of depressed blood levels of ionized calcium. Normal levels of ionized calcium were not maintained throughout a 24-hour monitoring period. The patient had tetany during a period of rapid reduction in ionized calcium levels, and an appropriate rise in circulating immunoreactive parathyroid levels was never demonstrated. Induced hypocalcemia during citrate infusion did not stimulate parathyroid secretion, nor did infusion of magnesium. We conclude that parathyroid insufficiency may be associated with Wilson's disease. We speculate that it is due to deposition of copper in the parathyroid glands.