female pattern baldness. Progressive thinning of hair throughout the entire head caused by genes, age and hormones. It usually develops at a much slower rate than male pattern baldness. 5-Alpha-Reductase: The Chemical that is responsible for transforming testosterone into dihydrotestosterone. 5-Alpha-Reductase Inhibitors: Prevent the body from converting testosterone to DHT by blocking the action of the enzyme 5-alpha reductase.