Osmotic Fragility of Red Blood Cells of Hypothyroid, Hyperthyroid Patients and Control Subjects

Many hypo and hyperthyroid patients are anemic. Changes in concentration of thyroid hormones can affect Na+- K+ ATPase number and activity and also phospholipid composition of the cell membranes leading to changes in the surface to volume ratio and strength of membrane. In this study, the osmotic fragility of the red blood cells from non-treated hypo and hyperthyroid patients diagnosed on the basis of clinical examinations and paraclinical data were compared to that of control subjects. Written consent was obtained from all subjects. After washing three times with normal saline, red blood cells were placed in varying sodium chloride (NaCl) concentrations (0-0.9gr%), following which, fragility was assessed with routine colorimetry methods. To do this, after the incubation period, tubes were centrifuged and the optical densities of the tubes was measured. Hemolysis percent in tubes was calculated on the basis of 100% hemolysis in the tubes containing 0 gr% of NaCl. The results indicate that the osmotic fragility of the cells from hyperthyroid patients in 0. 45gr% NaCl (74.6%±30.2) was significantly (p<0.01) lower than control subjects (93.8%±9.1). Osmotic fragility of red blood cells in 0. 5 g percent concentration of sodium chloride in hyperthyroid patients (27.8%±26.0) was significantly less (p<0.001) compared to the controls (63.5%±27.5). It appears that this change cannot be explained by changes observed in red blood cell indices (micrococytosis hypochromia). According to the results of this study one can conclude that anemia reported in hypo- or hyperthyroid patients is not due to high osmotic fragility of the red blood cells and other causes need to be investigated.