Aspirin Increases Serum Lithium Ion Levels

To the Editor.—  Reimann and her colleagues recently published the results of a study of the effects of aspirin on serum lithium ion levels and renal lithium ion clearance.¹ They found that aspirin did not cause a decrease, but rather a slight increase, in lithium ion clearance and a concomitant slight decrease of serum lithium ion levels. Their results stand in contrast to those of earlier studies with other inhibitors of prostaglandin synthesis, such as in domethacin, phenylbutazone, and diclofenac,^2-5 which cause a decrease in lithium ion clearance and an increase in serum lithium ion levels.We had begun a pilot study of the effects of aspirin on lithium ion handling when the article by Reimann et al appeared in the Archives. Our subject was a 43-year-old, healthy, nonsmoking man. His diet was not metabolically controlled, but he abstained from caffeine-containing beverages before and during the study. Lithium