Anthranilic acid-uraemic toxin damaged red cell's membrane.

Normocytic normochromic anaemia is a common syndrome present in patients with chronic renal insufficiency (CRI). Simultaneously in these patients the increase in L-tryptophan (TRP) degradation via kynurenine pathway is observed. On the basis of these observations we tried to examine whether one of the TRP metabolites, anthranilic acid (AA), shows interaction with membranes of erythrocytes and because of that it may contribute to anaemia development. In patients with CRI we have observed changes characteristic for normocytic normochromic anaemia, such as the decrease in erythrocyte count, haemoglobin concentration, haematocrit and the decrease in erythrocyte osmotic resistance as well as the increase in AA concentration in plasma in comparison to healthy subjects. We have also noticed the existence of a positive correlation between anthranilic acid concentration and creatinine and urea concentrations and also negative relationships between anthranilic acid concentration and haematological parameters. Moreover, incubation of healthy erythrocytes with 10 and 100 microM AA caused haemolysis curve movement to the right, which shows decrease in osmotic resistance. In conclusion, the increase in plasma AA concentration might be one of many factors, which damage erythrocyte membrane, and thereby contributes to anaemia development in patients with CRI.