Imparied calcitonin secretion in patients with Williams syndrome.

Williams syndrome is associated with neonatal hypercalcemia of unclear pathogenesis. To learn more about the hormonal control of calcium metabolism in patients with Williams syndrome, we studied five such children, with intravenous calcium and parathyroid hormone infusions as provocative stimuli. These patients were found to have significantly higher mean baseline calcium concentrations, delayed clearance of calcium after intravenous calcium loading, and blunted calcitonin responses after calcium infusion, compared with a group of seven normal children. No abnormalities of vitamin D metabolite concentrations were found, either before or after parathyroid hormone stimulation. Our studies demonstrate that patients with Williams syndrome have a defect in the synthesis or release of immunoreactive calcitonin. A deficiency of calcitonin may explain the abnormalities of calcium metabolism seen in these patients and can serve as an important endocrine marker for Williams syndrome.