Androstenedione: A steroid produced in the adrenal gland that is a precursor to testosterone and other male hormones (androgens). Known popularly as andro, it has been used as a supplement to increase muscle strength. Taking andro raises testosterone levels above normal. Side effects include acne, male baldness, and a decrease in 'good' cholesterol (which may predispose to heart disease and stroke).
Last Editorial Review: 6/9/2016