Utilization of Glycerol-C14 for Intestinal Glyceride Esterification: Studies in a Patient with Chyluria *

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Abstract
Two studies of glycerol-Cl4 incorporation into chyle lipids have been performed in a patient with chyluria. After the intraluminal administration of a glycerol-C14 and fatty acid mixture, between 15 and 18% of the lipid-glycerol excreted in the urine in 24 hours was found to be labeled, and as much as 59.5% incorporation was calculated in one urine specimen. The carbon14 labeling of the excreted glyceride-glycerol was almost identical to that fed, suggesting that incorporation occurred without extensive prior metabolism of glycerol. Glycerol-C14 was incorporated mainly into triglycerides of chyle, but significant labeling of other lipid fractions was observed. No labeling of mono-glycerides occurred, indicating that glycerol was not incorporated into this fraction. The urinary lipid fatty acid pattern differed significantly from the pattern of fatty acids administered, implying considerable dilution with endogenous lipids. These studies suggest that glycerol released in the intestinal lumen during triglyceride hydrolysis may be reutilized for glyceride synthesis in the mucosa. Should this occur, the validity of previous calculations of the extent of intestinal glyceride absorption is in question.