Lithium Increases Platelet Count

To the Editor: Lithium carbonate, the primary treatment for manic-depressive illness, has consistently been reported to increase leukocyte counts^1,2 without affecting erythrocytes or reticulocytes,¹ when administered in therapeutic doses. Some^3,4 but not all studies^5,6 have reported increased platelet counts: these, however, are limited by the brief (one to two weeks^4,5) or variable duration³ of lithium therapy, the use of comparison data from unmedicated controls rather than paired data,⁴ and the failure to compare directly the effect of lithium on platelets and white cells in the same patients.³ Therefore, we studied the effects of acute lithium treatment on white-cell and.