Glucose administration and heme catabolism after caloric restriction.

Heme catabolism was monitored through the determination of total serum bilirubin and endogenous production of carbon monoxide in 6 healthy males before and after administration of 100 g of glucose orally and intravenously, respectively. To facilitate comparison, hyperbilirubinemia was induced through a 36-hr period of subtotal caloric restriction before the study. A decrease in production of carbon monoxide was seen after glucose given orally as well as intravenously, whereas total serum bilirubin decreased significantly only after glucose orally. It is suggested that oral as well as intravenous glucose administration temporarily inhibits heme catabolism, at least when given after a period of caloric restriction. In addition, oral glucose might have--probably via a gut-related factor--a facilitating effect on liver uptake of bilirubin.