PLASMA NITRATE CONCENTRATION IN INFECTIVE GASTROENTERITIS AND INFLAMMATORY BOWEL-DISEASE

Background-In subjects on a low nitrate diet, plasma nitrate concentra tion and urinary nitrate excretion are thought to reflect endogenous n itric oxide (NO) production, and have been reported to increase during infective and inflammatory bowel disease. Aims-To compare the extent of NO production in patients with infective versus non-infective forms of bowel dysfunction. Subjects-Four groups: 20 healthy, volunteer cle rical and laboratory staff, 12 patients with irritable bowel syndrome, 19 patients with inflammatory bowel disease, and 20 patients with inf ective gastroenteritis. Methods-The plasma nitrate concentration was d etermined with a copper coated cadmium column and spectrophotometry. M ean and median plasma nitrate concentrations were calculated and compa red within the four groups. Mann-Whitney distribution free rank testin g was used to compare the median values. Results-Median plasma nitrate concentrations in the four groups were: controls 32.7 mu mol/l; irrit able bowel syndrome 35.5 mu mol/l; inflammatory bowel disease 35.1 mu mol/l; and gastroenteritis 117.9 mu mol/l (p<0.001 gastroenteritis v a ll other groups). Conclusions-Plasma nitrate concentration could serve as a discriminant between infective and inflammatory or functional bo wel disease in patients presenting with diarrhoea. It is not clear why there is considerable difference in endogenous nitrate synthesis in t hese two conditions, which are both characterised by severe gut inflam mation.