Nutritional defects in patients with malabsorption.

In developed societies nutritional deficiencies are often due to malabsorption. Most causes of malabsorption are related to one or more of the following: (I) mucosal damage, (2) bile salt deficiency, (3) stagnant loop (blind loop) syndrome, (4) deficiency of digestive enzymes, (5) operations on the gastrointestinal tract, (6) transport defects. More than one mechanism may be operative in some of the disorders producing malabsorption, for example malabsorption in patients with mucosal damage may be partly due to deficiency of disaccharidase enzymes as well as to the direct effect of the damage to the mucosa. The common nutritional deficiencies seen are: ( I ) anaemia, (2) oedema, (3) bone disease, (4) bleeding tendencies. Anaemia in patients with malabsorption is commonly caused by iron or folate deficiency or a combination of these. More rarely anaemia may be due to vitamin B,, deficiency, particularly in conditions where the terminal ileum is resected or there is bacterial contamination of the small intestine. Fe deficiency may be due to failure to absorb dietary Fe (Badenoch & Callender, 1954, 1960; McGuigan & Volwiler, 1964) and possibly also to loss of Fe when the rate of desquamation of intestinal cells is increased (Sutton, Baird, Stewart & Coghill, 1970). Malabsorption of folate may also be demonstrated where there is mucosal damage (Girdwood, 1953; Anderson, Belcher, Chanarin & Mollin, 1960; Hoffbrand, Douglas, Fry & Stewart, 1970). Very rarely pyridoxine deficiency may be important (Dawson, Holdsworth & Pitcher, 1964). Oedema is caused by hypoproteinaemia, to which many mechanisms may contribute; failure to absorb amino acids and peptides, loss of protein from the damaged intestine, metabolism of amino acids by bacteria in the blind loop syndrome, and defective hepatic synthesis of albumin following malabsorption are all relevant in considering the pathogenesis of hypoproteinaemia. Bone disease is more often in the form of osteomalacia than of osteoporosis, at least when clinical symptoms occur. Malabsorption of vitamin D is at least partly responsible. Bleeding caused by failure to absorb vitamin K is a less common manifestation of malabsorption. In adult gastroenterological practice in Ireland by far the commonest cause! of malabsorption is coeliac disease. During a yyear period, fifty-eight patients with adult coeliac disease, and only six with other causes of malabsorption, were seen. These six included patients with radiation disease of the small intestine, diverticulosis of the small intestine and fibrocystic disease of the pancreas.