The Absorption and Excretion of Calcium and Phosphorus in Three Patients with Colostomy and Ileostomy.

It is generally believed that calcium and phosphorus are absorbed from the small intestine and excreted through the kidneys and the colon. The chief factors which influence the absorption from the small intestine are the hydrogen ion concentration of the content of the bowel, the peristaltic rate, and the proportion of the various types of food in the diet. Macfadyen, Nencki and Sieber in 1891 (1), McClendon in 1915 (2) and numerous investigators (3, 4, 5) more recently found the content of the small intestine to be acid most of the time. The strength of the acidity decreases from a pH of about 1.5 in the stomach to approximate neutrality at the ileocecal valve. In spite of this experimental work, one commonly encounters the statement that the content of the small intestine is alkaline. The pancreatic and biliary secretions are in fact alkaline, but these secretions are readily neutralized by excess of acid secretion from the stomach and intestine. The peristaltic rate, or rate of propulsion of the intestinal content, is largely controlled by the nature and bulk of ingested food. A marked increase in the rate of propulsion of content would decrease the time for absorption of calcium and phosphorus as well as other minerals and foodstuffs and would increase the amount of materials retained in the lumen. Diets containing large amounts of fats, excesses of either calcium or phosphorus and highly alkaline diets have been shown by Farquharson, Salter, Tibbets and Aub (6) and others to decrease calcium and phosphorus absorption from the bowel, while acid foodstuffs and proper calcium-phosphorus ratios lead to increased calcium and phosphorus absorption. In man it has not been possible heretofore to study calcium and phosphorus exchange in the small bowel independent of colonic excretion, due to the difficulty of distinguishing dietary calcium and phosphorus retained in the stool from that excreted into the intestine. An unusual opportunity for study of the interchange of calcium and phosphorus through the small intestine independent of colonic excretion was afforded by three patients in whom tumor of the cecum necessitated both ileostomy and colostomy, thereby permitting separate collection of colonic and ileal excretion.