Polycythemia in hypothyroid infants

M. E. Weinblatt, P. Fort, J. Kochen and M. DiMayio

Twenty-three infants with congenital hypothyroidism were evaluated for the presence of anemia. Though no patient was found to be anemic, six (26%) had elevated hemoglobin levels, some with significant elevations. Pathogenesis of this finding is unclear, as none of the effects of thyroxine on erythropoiesis previously described would result in polycythemia. Pediatricians caring for hypothyroid infants should be aware of this association so as to be better prepared for any complication related to the hyperviscosity syndrome.