Hematological parameters and osmotic fragility of red blood cells in experimentally induced hyperthyroidism in rats

Background: Althoughhyperthyroidism is associated with anemia in men, the exact mechanism is not very well known. In the hyperthyroid state, the activity of this pump in red blood cells is decreased, so changes in the maintenance of the cell volume and the fluidity of the membrane of RBCs occur and changes in both the osmotic resistance, as well as changes in the blood profile in the hyperthyroid state are expected.
Objectives: This study was designed to investigate the possible impact of hyperthyroidism on the hematological parameters and osmotic fragilityof the red blood cells (RBC) in male rats.
Materials and Methods:Forty-eight male wistar rats (body weight, 221 ± 4g) were divided into 4 groups (10-13 each). Levo-thyroxine treated groups (I and III given 12mg/L levothyroxine in drinking water for 30 and 60 days respectively), while the control groups (groups II and IV) received only tap water. Blood samples were collected to measure hormone levels and osmotic fragility. The osmotic fragility was tested by incubation of RBCs at 37?C for 30 min in different concentrations of NaCl (0 – 0.9 g/100 ml). The extent of hemolysis was measured by colorimetry of the supernatant. Percent hemolysis was calculated on the basis of the 100% hemolysis in the first tube (zero NaCl).
Results: Results of the study show that although hemoglobin (16.4 ± 0.3g/dL), haematocrit (52.2 ± 1.4%), mean corpuscular hemoglobin (18.2 ± 0.3pg) and mean corpuscular volume (57.4 ± 0.8fL) in group III differed significantly (P < 0.05) compared to the control group (15 ± 0.4, 46.7 ± 1.2, 17.2 ± 0.3, 53.6 ± 0.5 respectively), the osmotic fragility showed no significant difference.
Conclusions: The results of this study indicate that not only does experimentally induced hyperthyroidism not induce anemia in rats, but it apparently enhances the erythropoesiswithout alteration of the osmotic fragility of the RBC. Exploring the mechanism may further help to explain the altered osmotic fragility observed in humans. 

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Please cite this paper as: 
Zahediasl S, Habibi G, Ghasemi A, Pashaei Rad S, Shiva N. Hematological parameters and osmotic fragility of red blood cells in experimentally induced hyperthyroidism in rats. Int J Endocrinol Metab. 2010;8(2):74-78.