The effects of X-ray irradiation and the thyroid gland on the erythropoietic system were studied. -
in the white male rabbits. The total body irradiation was done in doses of 250 r and 500-r to each´ ´. of 5 rabbits for 10 days. The factors were 220 KV, 10 mA, FLIi 4 Cu±1: mmAl (HVL:2.0 mm. ´´ Cu) 50 cm F.S.D. The thyroid dysfunction was experimentally induced.by. giving 2nig_of thyroid. tablets per kg body weight for 15 days in 5 rabbits for hyperthyroidism,and.by giving-1.5 mC:of-: -."´I per kg body weight in another 5 rabbits for hypothyroidism. Fourteen healthy, rabbits_ were used.:.
as control. The hematologic changes and ferrokinetic..data obtained from "´,Fe and. apparent half.".",;
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survival of the red blood cells obtained from "Cr were compared Following were the results:
A. X-ray irradiated group; ` -
1. There were no significant changes in hematologic findings except for leucopenia. -A slight.´ decrease of red blood cells was observed in 500r irradiated -animals.
2..The decreases in the iron ´turnover rates of the plasma And red ´blood cells as well as in the´ red cell renewal rate were found in both groups. A significant decrease of -the red cell* iron., utilization rate was observed in the 50o r irradiated animals.
3. The apparent half survival times of the red blood cells were slightly, in the 250 r (12.1±0.80, days), and markedly shortened in the 500r irradiated animals (9.8-´-1.38 days). the normal being 14.0±1.6 days.
4. It appears, therefore, that the anemia caused by X-ray irradiation is due to the inhibition of. hemopoietic function and the excess destruction of the red blood cells. B. Thyroid dysfunction group;
1. The slight increases of the red blood cell count and circulating blood volume with the normal.
serum iron level were observed in the hyperthyroid group, while the decreases of the red and white blood cell counts, hemoglobin and hematocrit values with a marked decrease of the serum iron level in the hypothyroid group.
2. A marked decrease of the plasma iron disappearance rate with increases of plasma iron turnover, red cell iron utilization and red cell iron turnover were observed in the hyperthyroid group, while the marked delay and decreases in the hypothyroid group.
3. The apparent half survival times of the red blood cells were almost the same with the control in the hyperthyroid group, (14.0±1.58days) while a marked shortening in the hypothyroid group (10.6±0.30 days).
4. It was reconfirmed that the thyroid hormones bear a close relationship with the erythropoietic system, namely, the latter is stimulated by the former. The lack of the thyroid hormones thus induces the bone marrow depression leading to anemia the major cause of which, therefore, is not hemolysis.
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