FIELD: medicine. SUBSTANCE: method involves taking sample, treating it for precipitating proteins with reagent containing zinc sulfate. Calibration curve is built to describe optical density dependence on nitrite concentration in reference set of solutions of various concentrations. Nitrates are reduced to nitrites in the sample under study by means of reagent containing cadmium. Optical density of the sample stained using Griss method is determined. The optical density values of the reference and test sample are compared using the calibration curve. Nitrogen oxide metabolites are determined in the sample under study. Reduction activity of the reagent is restored by washing it in 0.1 M hydrochloric acid solution. Patient is prepared for examination in advance before taking samples by excluding exogenous nitrates to be supplied into the organism by administering nitrate-excluding diet and therapy during 2-3 days. Nitrate-to-nitrite transformation is carried out by means of nitrate reducer reagent set containing copper. To determine nitrogen oxide presence in blood sample, the sample is to be taken in heparin presence. The sample is treated with centrifuging to produce plasma. Proteins are precipitated with zinc sulfate. The produced mixture is repeatedly centrifuged and liquid part is removed. Washing procedure is carried out with 0.1 M hydrochloric acid solution, distilled water, 1% copper sulfate solution, distilled water applied in succession, 10 s in each active solution. EFFECT: enhanced effectiveness and accuracy of diagnosing method. 4 cl
