The malabsorption syndromes. Some clinical problems.

I HAVE BEEN interested in the malabsorption syndromes for a long time and one of the fascinations of a continued interest over the years is to watch the emphasis change as new knowledge is added and old problems are solved. When I reviewed the subject in 1960 the classical idea that all the signs and symptoms of the malabsorption syndromes were due to failure of absorption of essential substances still held the field, but even then this was difficult to sustain. It was held, for example, that the dermatitis, glossitis and cheilosis that occurred in some patients, were due to faulty absorption of B vitamins and yet it was known that with one or two notable exceptions the absorptive capacity of the small intestine for the water soluble vitamins was enormous, and that even in the presence of gross steatorrhoea enough could be absorbed to satisfy the body's needs. Gradually, we have had to come to realise that malabsorption is only one facet of the problem, even if it is the easiest to recognise. In the presence of gross disorganisation of the small intestine not only are substances poorly absorbed but the normal losses by secretion and exudation into the lumen of the gut may be greatly increased either by direct seepage into the lumen or as a result of increased exfoliation of cells from the mucosal wall. Creamer and Croft (1970) have estimated that in normal man 60,000,000 cells may be lost daily from the small intestine together with 80 gms. of protein. Sixteen per cent of the protein lost is contained in the exfoliated cells. The greater quantity of this, of course, is digested and reabsorbed but in coeliac disease the loss of cells and protein may be increased six-fold and may contribute significantly to the hypoproteinaemia which occurs. It is known that not only protein but also iron and vitamin B12 are lost both by exfoliation and exudation and it may well be that there is an increased loss of many other essential substances when the mucosa is damaged. Moreover, the patient with malabsorption is at a double disadvantage because substances which are lost into the lumen of the gut are likely to be less wellabsorbed than in normal persons. Finally, in coeliac disease and other conditions associated with malabsorption, failure of absorption and increased loss into the lumen of the bowel may not be the only factors of importance. It is quite possible that abnormal substances, the result of faulty digestion or bacterial action, may be absorbed and give rise to far-reaching effects. Perhaps the first pointer to this came from an observation by England, French and Rawson (1960) some years ago. They studied a patient with Whipple's disease and a light sensitive dermatitis who was found to be excreting abnormal porphyrins in the stools. Treatment with antibiotics abolished the porphyrins from the stools and cured the dermatitis. The exact reason for the improvement remained uncertain but it could have been due