Differential diagnosis of maldigestion and malabsorption of fat. I. Comparison of the radioactivity of triglyceride and non-esterified fatty acid in fecal fat using purified 131I-triolein.

To differentiate maldigestion from malabsorption of fat, we compared the radioactivity of triglyceride with non-esterified fatty acid in fecal fat after ingestion of radiochemically purified 131I-triolein. A large amount of radioactivity was present in the triglyceride fraction from patients with pancreatic insufficiency, while such was found only in non-esterified fatty acid fraction in patients with short bowel syndrome, as determined by thin-layer chromatogram scanning. Thus, the "Digestion-Absorption Index" was calculated as a ratio of the radioactivity of triglyceride to that of non-esterified fatty acid. Mean Digestion-Absorption Index was 0.946 in the maldigestive group, and 0.045 in the malabsorptive group, and there was a statistical significance. However, an overlap in a few cases was confirmed in the area of 0.10 +/- 0.02, when this index was plotted on a table of semilogarithms. We assumed that this overlap was chiefly the result of maldigestion plus malasorption of fat.