The folic acid absorption test compared with other laboratory tests for malabsorption.

In 25 patients with malabsorption, the folic acid urinary excretion (TRIFA) test was compared with the degree of steatorrhoea, the Schilling test, and the D-xylose test. No correlation was found between the faecal lipid excretion, the Schilling test, and the TRIFA test, whereas the TRIFA test did correlate fairly well with the D-xylose test. It is concluded that the TRIFA test does not replace estimations of faecal lipid excretions in the diagnosis of intestinal malabsorption. As it mainly supplies information about absorptional capacity in the upper small bowel, it is complementary to the Schilling test, which chiefly measures the absorption in the lower intestine. Finally, the TRIFA test has several advantages over the D-xylose test in practical clinical use.