RESUMEN
Hyperthyroidism is associated with anemia. Since thyroid hormones, by acting on Na+/K+-ATPase activity and numbers, and also on the lipid composition of the membrane can alter the fragility of red cells, in this study, use compared the osmotic fragility of red cells in hyperthyroid rats to that of controls. Forty eight male Wistar rats [body weight, 221 +/- 4g] were divided in 4 groups. Group I consumed L-thyroxine [12mg/L in drinking water] for 30 days, group II was the control for group I, group III consumed L-thyroxine for 60 days and group IV was the control group for the group III. At the end of the intervention period, hormonal and biochemical measurements were done in blood samples. To assess the osmotic fragility, red blood cells [RBC] were incubated at 37°C for 30 min in different concentrations of NaCl and the extent of hemolysis was measured by colorimetry of the supernatant. Hemolysis percent was expressed in terms of percent hemolusis in presence of distilled water [100% hemolysis]. In this study although hemoglobin, haematocrit, mean corpuscular hemoglobin and mean corpuscular volume in group III were significantly [P<0.05] higher compared to group IV, osmotic fragility did not show any significant difference. The results indicate that hyperthyroidism in rat can not anemia and osmotic fragility of RBCs in hyperthyroid animals do not differ from control groups