Intrauterine hypercalcaemia and non-immune hydrops fetalis--relationship to the Williams syndrome.

We describe a 28-week-old fetus with severe non-immune hydrops. Intrauterine cord blood sampling revealed hypercalcaemia of 3.4 mmol/l (n = 2.6 +/- 0.1). Subsequently, a postmortem examination revealed supravalvular aortic and pulmonary artery stenosis together with extensive arterial calcification. The maternal calcium, 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, and parathyroid hormone levels were normal at delivery. This is the first time that hypercalcaemia has been diagnosed in utero. We speculate on the fact that the disorder resulted as a consequence of abnormal vitamin D metabolism in the fetoplacental unit, and that it might be related to the Williams syndrome.