Avaliação da interferência de fatores pré-analíticos na mensuração dos metabólitos do óxido nítrico e determinação dos intervalos de referência para uma população saudável

Abstract

Nitric oxide (NO) is a reactive free radical, that acts as a messenger molecule, mediating several functions, including vasodilation, platelet aggregation inhibition, neurotransmission, antimicrobial and antitumor activities. In several pathological conditions, NO is associated with increased circulatory concentrations of cytokines and endotoxins in inflammatory processes in especially. Because this radical to have a short half-life, its determination is difficult, therefore, measurement of metabolites nitrite/nitrate (NOx) is most often used to evaluate NO production. The objective of this study the effect of pre-analytical interferences been investigating on the NOx and determine the limits of urinary and serum reference for a healthy population. In the simulation of bilirubin, lipemia and hemolysis on serum samples, we evaluated the pre-analytical interference in the measurement of NOx All bilirubin concentrations used (9, 19, 38, 75, 150 and 300 mg /L), Intralipid® (0.67, 1.25, 2.5, 5 and 10 g/L) and hemoglobin (0.5, 1.0, 2.0, 4.0 and 5.0 g/L) resulted in a difference between the original amount of NOx being checked greater than 10 percent %, thus, considered an analytical interference. The reference limits were evaluated following the recommendations of the International Federation of Clinical Chemistry (IFCC), and urinary values of 46.1 mmol / L to 1533.0 mmol/L, and serum values 56.8 mmol/L at 340, 3 mmol/L for a presumably healthy population. Thus, we conclude that bilirubin, lipemia and hemolysis interfere with the measurement of serum activity of NOx. The reference limits were evaluated following the recommendations of the International Federation of Clinical Chemistry (IFCC), and urinary values of 46.1 mmol/L to 1533.0 mmol/L, and serum values 56.8 mmol/L at 340, 3 mmol/L for a healthy population. Thus, we conclude that bilirubin, lipemia and hemolysis interfere with the measurement of serum activity of NOx.