To the Editor.
—The recent article in the Archives by Lardinois and Mazzaferri1 ('Cimetidine Blocks Testosterone Synthesis') contains implications and misstatements that have been misleading to your readers.As the authors point out, the changes in plasma testosterone levels noted in their patient are unique and have not previously been reported with cimetidine hydrochloride therapy even in patients with drug-associated gynecomastia. Although a defect in 17-β-hydroxysteroid dehydrogenase may have been responsible, no substantial confirmatory data have been presented and we believe it unwarranted for the authors to have entitled their article in such an unequivocal fashion.Several other issues are raised by the article. The introduction of hyperprolactinemia is irrelevant to the case reported. As was the case in the patient described, prolactin levels have been consistently normal with the use of oral cimetidine. As pointed out by the authors, transient hyperprolactinemia has been noted only after rapid intravenous