[Low levels of selenium and activity of glutathione peroxidase in blood of patients with gastrointestinal neoplasms].

Selenium concentrations in the full blood and erythrocyte and plasma GSH-Px activity were determined in patients with cancer of the stomach, colon and rectum. The results were compared with those in the group of healthy subjects. Blood samples were collected into heparinized tubes prior to surgery. Selenium concentrations in the full blood and plasma were lower (75.5 ng/mL and 56.2 ng/ml, respectively) in patients with the cancer of the stomach than healthy subjects (99.5 ng/ml and 78.5 ng/mL, respectively; p < 0.0001). Concentration of this element in both full blood and plasma was also lower in patients with cancer of the colon and rectum (77.7 ng/mL and 61.0 ng/ml, respectively; p < 0.0001). Erythrocyte and plasma GSH-Px activity was also significantly lower (p < 0.001) in patients with cancer of the stomach than in healthy subjects, and amounted to 13.6 U/g Hb and 188 U/L, respectively. Activity of this enzyme in patients with cancer involving lower segment of GI tract amounted to 15.9 U/g Hb and 190 U/L of plasma, and was significantly lower (p < 0.001) than in normal subjects in whom it amounted to 21.0 U/g Hb and 256 U/L of plasma.