Adverse effect of 1,25-dihydroxycholecalciferol on erythrocyte precursors in the rat.

Administration of 1,25-dihydroxycholecalciferol (0.5 microgram/d/100 g body weight) to vitamin D repleted rats produced a significant decrease in the number of femoral marrow cells, specially in the erythroid line. Analysis of blood revealed slight anemia with reticulocytopenia. The survival time of 51-Cr-labelled red cells was unaffected by treatment, suggesting that bone marrow became unable to replace cells at a normal rate. The adverse effect on erythropoiesis appeared related to the degree of the concurrent hypercalcemia, which in turn depends upon the calcium content of the diet.