THE EFFECTS OF THIOURACIL ON THE HEMATOPOIETIC SYSTEM OF THE ALBINO RAT

1) Forty-seven albino rats were fed thiouracil in doses ranging from 0.05 to 0.225 gm. daily for from 5 to 78 days.

2) A slight decrease in the total number of red blood cells and a slight to moderate decrease in the hemoglobin content of the peripheral blood was noted in a high percentage of the rats upon which complete blood counts were performed. In a study of 361 specimens taken from treated animals no sustained variations from the normal range of total and differential white blood cell counts were noted.

3) Smears of the bone marrow revealed a definite decrease in the myeloiderythroid ration in 3 of 4 animals receiving 0.1 gm. of thiouracil daily for 78 days and in 6 of 7 animals to which 0.2 gm. of drug was given daily for 24 days.

4) The presence of granular deposits in the kidney pelvices was noted at autopsy in 7 rats.

5) In addition to the changes in the bone marrow, microscopic examination of sections of organs taken at autopsy revealed alterations only in the thyroid gland and in the kidneys. The former showed varying degrees of hyperplasia and diminution of colloid; the latter exhibited some evidences of tubular damage.