The Science of DHT: Why Hair Follicles Shrink
Understanding the biological mechanism of male pattern baldness, the 5-alpha-reductase enzyme, and how finasteride halts the process.
The Miniaturization Process
Androgenetic alopecia (male pattern baldness) is driven by two main factors: genetics and hormones. The specific hormone responsible is Dihydrotestosterone (DHT).
Testosterone is naturally converted into DHT by an enzyme called 5-alpha-reductase. In men who carry the genes for hair loss, the hair follicles on the top and front of the scalp are uniquely sensitive to DHT.
The Hair Growth Cycle & DHT
How DHT shrinks follicles over time (Miniaturization)
The follicle is deep and produces thick, terminal hair for 2-6 years.
DHT binds to the follicle, shortening the anagen phase and physically shrinking it.
The follicle can no longer produce thick hair, resulting in peach fuzz, then baldness.
When DHT binds to the androgen receptors on these follicles, it triggers a process called *miniaturization*. The anagen (growth) phase of the hair cycle becomes progressively shorter. Over several cycles, the follicle physically shrinks, producing thinner, weaker hair (vellus hair) until it eventually stops producing hair entirely.
Halting the Cascade
Because the root cause of the loss is enzymatic conversion, the most effective medical treatment is to block the enzyme. Finasteride is a 5-alpha-reductase inhibitor. By taking it daily, the conversion of testosterone to DHT is severely restricted.
Clinical data shows that 1mg of oral daily finasteride lowers systemic DHT levels by approximately 70%. For the vast majority of men, this is enough to completely halt the miniaturization process and preserve existing hair.