ERYTHROCYTE CREATINE LEVELS (EC) AND THE DIAGNOSIS OF HEMOLYTIC DISEASE IN NEWBORN INFANTS (HDN)

Abstract

In the diagnosis of HDN the reticulocyte count is insensitive, inaccurate and assesses red cell production only in the few days prior to testing. In adults it has been reported that EC is elevated in young erythrocytes and as an index of mean cell age is a valuable test for the diagnosis of hemolytic disease. Young cord erythrocytes, isolated by density centrifugation, had EC levels greater than older cells. EC (mg/dl ± SD) was 8.7 ± 1.33 in 7 women, 5.7 ± .64 in 6 men, 10.1 ± 2.97 in 12 fullterm newborns and 10.4 ± 2.57 in 26 premature newborns. In ABO-HDN cord blood EC was elevated (28.9 ± 18) in 9 infants in whom spherocyte counts (glutaraldehyde-fixed cells) were abnormally high and who developed jaundice in the first 24 hours of life. EC was also elevated in Rh disease and in other forms of HDN. These data suggest that in HDN, EC is a valuable diagnostic test. In 19 successive infants with idiopathic hyper-bilirubinemia requiring phototherapy, EC in cord blood was 3.9-10 mg/dl and quantitative assessment of erythrocyte morphology (Am. J. Ped. Hem./Onc. 4, p.45, 1983) was normal in all cases. Thus using accurate assessment of red cell morphology and mean cell age, no evidence of HDN was found in these cases, suggesting that an occult hemolytic process, evident at birth, is an unlikely contributing cause to the pathogenesis of idiopathic hyperbilirubinemia in newborn infants.