Increased nucleated erythrocytes in an infant with congenital hyperinsulinism.

A markedly elevated peripheral nucleated erythrocyte count is reported in a term nonmacrosomic infant with congenital hyperinsulinism born to a nondiabetic mother. With control of hypoglycemia and hyperinsulinism, the count declined to normal. A relationship of hyperinsulinism and erythropoiesis, not related to fetal hypoxemia, is considered.