Transcutaneous bilirubin monitoring predicts unexplained late-onset hemolysis in a very low birthweight infant.

BACKGROUND: In term infants, transcutaneous bilirubin (TcB) monitoring can be used to predict hemolytic hyperbilirubinemia. However, it is not clear whether the technique can also be used to predict unexplained late-onset hemolysis in very low birthweight (VLBW) infants. CASE PRESENTATION: The case was an infant with a birthweight of 1154 g who developed unexplained late-onset hemolysis at 8 days of age. The hyperbilirubinemia rapidly worsened, and therefore both phototherapy and exchange transfusion were performed. TcB levels were measured using the JM-105 jaundice meter and found to have increased by >3 mg/dL since before the onset, demonstrating for the first time that the device clearly detects changes in hemolytic rate. CONCLUSIONS: Although TcB levels did not correspond directly with total serum bilirubin levels in VLBW infants, the two values exhibited parallel changes in this case. Therefore, serial TcB monitoring may be useful in the early prediction of unexplained late-onset hemolysis in VLBW infants.

Lutheran.

The Lutheran blood group system consists of 19 antigens: four pairs of antithetical antigens--Lu(a)/Lu(b), Lu6/Lu9, Lu8/Lu14, and Au(a)/Au(b)--and 11 antigens of very high frequency. These antigens are located on four of the five immunoglobulin-like domains of both isoforms of the Lutheran glycoprotein. The LU gene is on chromosome 19 and comprises 15 exons. The two glycoprotein isoforms differ in the length of their cytoplasmic tails as a result of alternative splicing of intron 13. Lu(null) phenotype arises from homozygosity for inactivating mutations in the LU gene.The dominantly inherited Lu(mod) phenotype, In(Lu), results from heterozygosity for inactivating mutations in KLF1, the gene for the erythroid transcription binding factor EKLF. Clinically, antibodies of the Lutheran system are relatively benign. When hemolytic, they generally cause only mild, delayed hemolytic transfusion reactions or hemolytic disease of the fetus and newborn that can be treated by phototherapy. The Lutheran glycoproteins, which are members of the immunoglobulin superfamily of adhesion molecules and receptors, bind isoforms of laminin with alpha5 chains,components of the extracellular matrix abundant in vascular endothelia. The primary function of the Lutheran glycoproteins on RBCs could involve the transfer of maturing RBCs from the bone marrow to the peripheral circulation. They could also be involved in vascular occlusion and thrombotic events as complications of sickle cell disease and polycythemia vera, respectively.