Posttransfusion hemoglobinuria and myoglobinuria in neonates.

Posttransfusion positive dipsticks for occult blood do not differentiate hemoglobinuria from myoglobinuria, relatively common events in infants admitted to the neonatal intensive care unit. We studied posttransfusion plasma and urine hemoglobin and myoglobin in relation to occult blood positivity in the urine dipsticks, in 48 consecutive transfusions with packed RBC (28 neonates, birth weight 850-3,700 g, postnatal age 3-167 days). Urine dipsticks show a low sensitivity for detecting hemoglobin and also undervalue myoglobin, both possible in different amounts in the plasma and urine of ill neonates. However, posttransfusion occult blood positive urine dipsticks due to myoglobinuria are present in 10% of transfused neonates.