Noninvasive evaluation of liver metabolism by 2H and 13C NMR isotopomer analysis of human urine

Mammalian liver disposes of acetaminophen and other ingested xenobiotics by forming soluble glucuronides that are subsequently removed via renal filtration. When given in combination with the stable isotopes H-2 and C-13, the glucuronide of acetaminophen isolated from urine provides a convenient chemical biopsy for evaluating intermediary metabolism in the liver. Here, we describe isolation and purification of urinary acetaminophen glucuronide and its conversion to monoacetone glucose (MAG). Subsequent H-2 and C-13 NMR analysis of MAG from normal volunteers after ingestion of (H2O)-H-2 and [U-C-13(3)]propionate allowed a noninvasive profiling of hepatic gluconeogenic pathways. The method should find use in metabolic studies of infants and other populations where blood sampling is either limited or problematic. (C) 2003 Elsevier Science (USA). All rights reserved.