Effect of fasting on diarrhoea in collagenous colitis

Abstract

Background/aim: Diarrhoea in collagenous colitis has been considered as secretory though the pathophysiology has been studied thoroughly in only a few patients. The result of fasting is one way to distinguish between secretory and osmotic diarrhoea. Our aim was to investigate the effect of fasting on diarrhoea in collagenous colitis.

Methods: Fourteen patients with collagenous colitis were admitted to the hospital for investigation. All were female. Five of these did not have diarrhoea during admission and were excluded. Stools were examined for weight, electrolytes, pH, fat and osmolality during a period on a normal diet and during fasting.

Results: During the fasting period the faecal weight was significantly reduced from median 757 (440-3,198) to 191 (22- 2,197) g. The faecal sodium concentration was also reduced, though not significantly, during fasting from median 65 (29-85) to 45 (19-88) mmol/l. The osmotic gaps varied according to the method of calculation applied.

Conclusions: The data indicate that the cause of the diarrhoea in collagenous colitis could be multifactorial. In some patients an osmotic factor dominates and in others a secretory factor, while in some patients a combination of both seems to exist.