Nitric oxide end products in patients hospitalized for diarrhoea

Objective Increased nitric oxide (NO) has been demonstrated in inflammatory bowel diseases (IBD). Plasma and urinary nitrite and nitrate are usually c onsidered to reflect global NO generation. Recently it has been suggested t hat plasma nitrate may be a discriminant indicator between infectious enter ocolitis (IC) and IBD. To investigate this hypothesis we compared plasma an d 24 h urinary nitrite and nitrate in 13 healthy controls, 44 patients with IBD [Crohn's disease (CD) n = 30; ulcerative colitis (UC) n = 141, 16 pati ents presenting with IC and seven chronic radiation enterocolitis (RE) pati ents. Results Despite a trend towards higher plasma nitrate in IC (54.6 +/- 11.4 mu mol/l) than in the other groups (CD: 38.4 +/- 4.8, UC: 34.8 +/- 8.4, RE: 34.7 +/- 7.5, controls: 31.1 +/- 5.2), this difference was not statistical ly significant. Urinary nitrate was higher in IBD, IC and RE than in contro ls, with no difference between these groups. Nitrite concentrations were no t different. Nitrate levels were positively correlated with blood and 24 h urinary neopterin (e.g. plasma nitrate and blood neopterin: r = 0.54, P< 0. 0001), and in some cases, to C-reactive protein. Conclusions High nitrate tin our case only urinary nitrate) appears to be s econdary to the magnitude of the inflammation rather than the aetiology of the diarrhoea. It should therefore more likely be considered as a marker of the severity of the inflammatory response rather than used as a discrimina nt indicator between IC and IBD patients. Eur J Gastroenterol Hepatol 11:10 13-1018 (C) 1999 Lippincott Williams & Wilkins.