Serum Radioactivity of ¹⁴C-Triolein and ³H-Oleic Acid Ingested in a Test Meal

Abstract

A double-tracer technique to estimate lipid digestion was investigated. ³H-labelled oleic acid and ¹⁴C-labelled triolein were ingested in a test meal. The serum radioactivity of ³H after ingestion of labelled oleic acid depends on absorption and metabolism of free fatty acids, while serum radioactivity of ¹⁴C from triolein, in addition to the former, depends on triglycerol digestion. This study shows that the ratio between ³H and ¹⁴C 2 h after the test meal gives a good qualitative and quantitative estimation of lipid digestion: the ³H/¹⁴C ratio in patients with maldigestion is significantly higher than for normals (P < 0.01), the predictive value of the ³H/¹⁴C ratio in the diagnosis of maldigestion is high, that of a positive result being 1.0 and that of a negative 0.93, and quantitatively the ³H/¹⁴C ratio shows a highly significant correlation with faecal fat (P < 0.001). The test is very easy to perform, lasts for only 2 h, and is without discomfort to the patient or nursing and laboratory staff. It gives information like or superior to that of faecal fat measurement.

Key-words:

• Maldigestion
• radioisotope test