Increased renal medullary echogenicity in patients with Williams syndrome.

Williams syndrome is characterized by peripheral artery stenosis such as supravalvular aortic stenosis, a distinctive dysmorphic facies, mental retardation and occasionally by transient infantile hypercalcemia. Twenty-five children with this syndrome underwent abdominal ultrasound examinations in our institution between 1983-1988. Five showed an increase in the renal medullary echogenicity consistent with medullary nephrocalcinosis. The echogenicity did not change with time. Two of the five had documented hypercalcemia in infancy. The other three did not have calcium measurements in infancy. No patient with normal serum calcium measurements during infancy developed nephrocalcinosis. Renal ultrasound may add information as to the incidence of infantile hypercalcemia in Williams syndrome.