Study of Urinary and Fecal Excretion of Radioactive Chromium Cr51 in Man. Its Use in the Measurement of Intestinal Blood Loss Associated with Hookworm Infection1

Abstract

Two noninfected and 6 hookworm-infected subjects were given their own chromium tagged erythrocytes via a duodenal tube. Fecal recovery was on the average 96.7% of administered radioactivity, and urinary recovery 1.7%. In 10 noninfected subjects, 2 of them with marked anemia, whose circulating erythrocytes had been tagged with Cr51, there was little fecal excretion of radioactivity (average 1.27 cc of "blood" per day). Most of the daily excreted radioactivity appeared in the urine (96.3% of the total activity recovered daily, on the average) in the 8 nonanemic subjects. A comparison of the radioactivity in blood and feces of patients with Cr51 marked erythrocytes appears to be a valid way of estimating intestinal blood loss. The circulating erythrocytes of 21 patients with varying severity of hookworm infection were marked with Cr51, and intestinal blood loss due to the hookworm was measured by comparing stool and blood radioactivity. Blood loss per day in the stool ranged from 2.0 to 251.5 cc, in rough proportion to the severity of infection. In 12 patients with pure Necator americanus infection, the blood loss per day per hookworm was on the average 3.11 x 10-2[plus or minus]1.72 x 10-2 per cc. Five patients harbored mixed Necator-Ancylostoma worms. Blood loss per Ancylostoma duodenale was estimated to lie in the neighborhood of 0.2 cc/hookworm per day. Calculated iron loss ranged from 1.2 to 29.1 mg/day. There was a rough correlation between number of ova in the stools and amount of blood lost. On the average, patients lost 2.74 cc/day/1000 ova/g of stool, with standard deviation of [plus or minus]1.5 and range of 0.82 to 7.14 cc.