Plasma nitrate as an index of nitric oxide formation in patients with acute infectious diseases

In humans, the role of nitric oxide (NO) in host defence is controversial. We prospectively studied plasma levels of nitrate, the stable end-product o f NO formation, during acute infection in 43 patients controlled with regar d to dietary nitrate/nitrite, During acute gastroenteritis the mean plasma nitrate Level was significantly increased compared with at recovery 4-5 wee ks later (118 vs. 32.5 mu mol/l; p < 0.001), in contrast with the findings in patients with acute pneumonia (PN; 34.6 vs. 42.8 mu mol/l) or febrile ur inary tract infection (UTI; 27.7 vs. 31.3 mu mol/l). In a second group of 2 0 retrospectively studied patients with severe PN or UTI, of whom 70% were bacteraemic, no significantly increased nitrate levels could be demonstrate d during the acute stage of infection. These findings indicate that increas ed NO production, as measured by plasma nitrate, is not a general finding i n patients with acute infectious diseases, but may rather be associated wit h certain pathogens or sites of infection.