ABSTRACT
The urinary D-glucaric acid of 86 full-term newborns was determined on the 10th day of life. Of these, 28 had jaundice due to glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, 24 jaundice of unknown etiology and 18 Rhesus incompatibility. Practically all the cases of the first two groups had a greatly decreased D-glucaric acid excretion whereas this was not a constant finding in the 18 cases with Rh-incompatibility. Normal values were found in 16 healthy controls of the same age. These findings suggest that in severe neonatal jaundice due to G-6-PD deficiency and in jaundice of unknown etiology, there is a greatly reduced excretion of endogenously formed D-glucaric acid, due probably to decreased activity of liver enzymes involved in the metabolism of glucuronic acid. This defect probably contributes to the unconjugated hyperbilirubinemia in these newborns.