Pitfalls in diagnosing galactosemia: false negative newborn screening following red blood cell transfusion.

Newborn galactosemia screening programs using the fluorescence spot test to detect red cell galactose-1-phosphate uridyltransferase activity are prone to inaccuracy if the screened infants have received blood transfusions. We describe an infant with galactosemia who received packed red cell transfusions in the first few days of life and was misdiagnosed after an initial positive screening test result. Although the patient was thought to have cytomegaloviral hepatitis, a percutaneous liver biopsy helped direct the evaluation toward identifying the galactosemia carrier state in both parents. This case report illustrates the need for careful consideration of the patient's history of transfusion of blood products when evaluating newborn screening results.