A DIRECT MEASUREMENT OF FOLIC ACID ABSORPTION IN HEALTHY CHILDREN DETERMINED BY A SINGLE STOOL SAMPLE TEST- A DOUBLE ISOTOPE TECHNIQUE SPECIALLY ADAPTED TO THE USE IN CHILDREN

摘要

The fractional folic acid absorption (FAFol) was determined in 66 patients with various gastrointestinal diseases by a double isotope technique, employing a single stool sample test (SSST), as well as a complete stool collection. The age of the patients ranged from 2.5 mo to 16.8 yrs(mean 6.3). The test dose was administered orally and consisted of 50 mikrog. of 3H folic acid (app. 20 mikroCi), carmine powder, and 2 mg 51CrCl3 (app.1.25 mikroCi)as the inabsorbable tracer. The wholebody radiation given to a 1-year-old child averaged 4.8 mrad, ie a negligible radiation dose. The stool and napkin contents were collected and homogenized by the addition of chromium sulfuric acid. The content of 51Cr was measured in a broad-based well counter and the quantity of 3H folic acid by liquid scintillation, after duplicate destillation. Estimated by SSST, the FAFol, which employs the stool with the highest content of 51Cr corresponding to the most carmine-colored stool, correlated closely with the FAFol based on complete stool collection (r=0.96, N=39, p 0.0001).The reproducibility of FAFol determined by SSST was assessed from double assays in 18 patients. For a mean of 81%, the SD was 4.6% which corresponded to a CV of 5.7%. The mean FAFol in 45 healthy children aged 9 mo to 16.8 yrs (mean 6.4) was 83% (range 66-95%). The FAFol levels showed no correlation with age. This study is the first attempt of direct measurement of folic acid absorption in healthy children.