Decreased nitric oxide serum level after pituitary adenoma resection.

BACKGROUND: Nitric oxide (NO) is synthesized by the conversion of Arginine (Arg) into the NO and Citrulline (Cit). Although the NO is involved into the pathogenesis of several physiological and pathological processes, the role of NO in pituitary adenomas (PA) progres-sion is not determined. Our purpose was to evaluate the relationship between NO and PA as well as the effect of tumor resection on NO metabolites level in serum.

METHODS: The study group consisted of 21 patients with PA, 18 patients with macroade-nomas and 3 with microadenomas. Venous blood samples were collected at two time-points; 1) before the surgery and 2) 3-5 days after PA resection. Arg and Cit levels were determined by the automated ion-exchange chromatography with usage of Amino Acids Analyser (AAA 400). Commercially available kit for the evaluation of nitrate/nitrite serum levels was applied for indirect assessment of serum NO level.

RESULTS: Significant decrease in NO concentration after the surgery was observed in com-parison with the time-point 1. Arg level did not significantly change during the study period. Cit level was ranged below the detection limit of applied method.

CONCLUSIONS: The decrease of NO level after the pituitary adenoma resection indicates the relationship between NO synthesis and PA occurrence.