THE DEVELOPMENT OF AN ANEMIA IN RATS AFTER THYROIDECTOMY AT BIRTH

Abstract

New born rats were thyroidectomized by the intraperitoneal injection of I¹³¹ and maintained on a low iodine diet. There was a cessation of body weight increase after the age of 3 weeks. The normal rise in erythrocyte count following birth stopped after 3 weeks. At 8 weeks of age the thyroidectomized animals had a RBC count 78% of that of the normal controls. Hematocrit and hemoglobin concentration also failed to rise after 3 weeks of age and at two months were 79% and 87% respectively of the normal values. At 3 months the value fell further to 59% and 74% of the respective normal levels. The bone marrow was aplastic. The relative weight of the spleen (mg/100 gm body weight) was decreased in the experimental animals and showed some atrophic changes with loss of germinal centers. Thus thyroidectomy of the newborn rat results in a progressive hypercliromic-microcytic anemia and the relationship of this anemia to that following hypophysectomy is discussed.