Depression of Plasma Testosterone Levels after Chronic Intensive Marihuana Use

Abstract

Twenty heterosexual men 18 to 28 years of age who used marihuana at least four days a week for a minimum of six months without use of other drugs during that interval were studied. Mean (± S.E.M.) plasma testosterone — 416 ± 34 ng per 100 ml — was significantly lower in this group than that in the control-group mean — 742 ± 29 ng per 100 ml — for age-matched men who had never used marihuana. Decreased testosterone was dose related. Abstention from marihuana use and stimulation with human chorionic gonadotropin during continued marihuana use produced marked increases in testosterone. Measurements of liver function, circulating gonadotropins, prolactin, Cortisol and thyroxine were within normal limits. Six of 17 men (35 per cent) showed oligospermia, and two men were impotent. The data suggest that chronic intensive use of marihuana may produce alterations in male reproductive physiology through central (hypothalamic or pituitary) action. (N Engl J Med 290:872–874, 1974)