[Measurement and its fluctuation of urinary glucaric acid in newborns].

It is known that urinary excretion of glucaric acid(GA) is an indirect index of hepatic P-450 microenzyme induction. We measured and analyzed urinary excretion of GA in 56 newborns and 26 mothers by a new method for the inhibition of beta-glucuronidase activity and obtained the following results. 1. The concentration of urinary GA was correlated with that of urinary creatinine and total bilirubin in newborns. 2. There were no significant correlations between gestational age, sex, body weight at birth, placental weight and the urinary GA concentration. 3. The urinary excretion of GA in newborns was decreased the in first few days after birth, but a transitional increase was observed on the fifth day after birth. 4. The concentration of urinary GA was correlated with that of direct bilirubin in serum on the fifth day after birth. 5. There was a negative correlation between the urinary GA concentration on the first day after birth and that of direct bilirubin in serum on the fifth day after birth. These results suggested that hepatic P-450 microsomal enzyme was induced by bilirubin in newborns and it was possible to estimate the clinical course of jaundice by measuring the urinary excretion of GA.