title: Plasma nitrate concentrations in children with infectious and noninfectious diarrhea.
abstract: BACKGROUND
  In patients with intact renal function and low dietary nitrate intake, plasma nitrate concentrations reflect endogenous nitric oxide production and are shown to be increased during inflammatory processes. The aim of this study was to compare plasma nitrate concentrations and hence endogenous nitric oxide production in children with infectious and noninfectious diarrhea and to determine whether plasma nitrate concentrations could serve as a discriminant test between acute and chronic diarrhea in children.
  
  
  METHODS
  Three groups of patients were identified: 14 patients with acute gastroenteritis, 13 patients with chronic noninfectious diarrhea, and 14 patients with no evidence of gastrointestinal pathology and no underlying infectious process, who served as control subjects. Plasma nitrate concentrations were determined spectrophotometrically using the Greiss reaction before reduction to nitrite with a copper-coated cadmium column.
  
  
  RESULTS
  Mean plasma nitrate concentrations were 405.3 micromol/L +/- 281.6 micromol/L (standard deviation) in patients with infectious diarrhea, 134.7 micromol/L +/- 77.0 micromol/L in patients with chronic diarrhea, and 54.1 micromol/L +/- 20.1 micromol/L in control subjects (F = 42.6, P < 0.0001; analysis of variance). Plasma nitrate concentrations were significantly higher in the infectious diarrhea group compared with the noninfectious diarrhea and control groups (Student-Newman-Keuls test, P < 0.5).
  
  
  CONCLUSIONS
  Although an optimal cutoff concentration cannot be defined, plasma nitrate concentrations in excess of 300 micromol/L are suggestive of an infectious process whereas values less than 100 micromol/L are indicative of noninfectious diarrhea.
authors.affiliation: Department of Paediatric Gastroenterology, St Bartholomew's and the Royal London School of Medicine, UK.
authors.forename: E
authors.initials: E
authors.lastname: Charmandari
authors.forename: N
authors.initials: N
authors.lastname: Meadows
authors.forename: M
authors.initials: M
authors.lastname: Patel
authors.forename: A
authors.initials: A
authors.lastname: Johnston
authors.forename: N
authors.initials: N
authors.lastname: Benjamin
mesh_terms: D000208:Acute Disease; D002908:Chronic Disease; D003141:Communicable Diseases / Q000097:blood / Q000175:diagnosis*; D003937:Diagnosis, Differential; D003968:Diarrhea, Infantile / Q000097:blood / Q000175:diagnosis*; D005260:Female; D005759:Gastroenteritis / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D008297:Male; D009566:Nitrates / Q000097:blood* / Q000652:urine; D009569:Nitric Oxide / Q000096:biosynthesis; D012016:Reference Values; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013053:Spectrophotometry
chemical_list: D009566:Nitrates; D009569:Nitric Oxide