The Role Of Hormones In Male Pattern Baldness

Male pattern baldness, or androgenetic alopecia, affects around 30-50% of men by age 50, which makes it the most common type of hair loss in men. Although there’s not just one single cause, MPB is largely hormonal. Research shows that a sex hormone called dihydrotestosterone (DHT) shrinks hair follicles over time until they no longer support healthy hair growth. This process, known as miniaturization, is why hair loss develops gradually in most men. Interestingly, DHT doesn’t affect all follicles equally and ones at the back and sides of the scalp are largely resistant to it. But it’s also those resistant follicles that make treatments like hair transplants so effective: they can be moved to thinning areas and continue to grow healthily to help men affected by MPB. 

The hormone behind male pattern baldness

Dihydrotestosterone is made when an enzyme called 5-alpha reductase converts testosterone in the body. This happens in several different places, including in the hair follicles themselves. DHT is far more potent than testosterone and has around five times more affinity for androgen receptors, a recent scientific review found. Androgen receptors are cell proteins within the follicle that bind to hormones like DHT and testosterone to influence hair growth. DHT binds aggressively to these receptors and that’s what causes the follicles on the scalp to shrink over time, so hair doesn’t continue to grow normally. Interestingly, the review also found that men who are born deficient in 5-alpha reductase don’t go on to develop male pattern baldness regardless of how much testosterone they have. This indicates that it's DHT and not testosterone that causes MPB.

Understanding hair miniaturization

Hair miniaturization is the process that begins once DHT binds to the androgen receptors and, as its name implies, the hair follicles gradually shrink throughout this process. This then causes the hair to become thinner and shorter. It helps to know how your hair grows first to properly understand this miniaturization process. Hair growth happens in cycles and each one takes several years to complete. The initial growth phase is the longest part of this cycle (and lasts about two to six years) and usually sees the hair grow between 1-2 cm per month. This is followed by a transition phase where the growth stops and then a natural shedding phase. 

DHT progressively shortens the growth phase which means your hair has less time to grow before it sheds. Also DHT shrinks the hair follicles, so the hair becomes thinner over time. The time it takes for new hairs to replace old ones that fall out also increases. This is why male pattern baldness takes years to develop and some men even don’t notice it until it’s already quite advanced.

Treating male pattern baldness (and the science behind it)

Some MPB treatments aim to reduce DHT production and block the 5-alpha reductase enzyme altogether, so there’s less DHT available to bind to the follicles in the first place. Research shows this type of treatment leads to a 30% improvement in hair growth with use over the long term. Hair loss treatment for men can also be tailored to how far along the hair loss is, but in most cases the sooner it’s addressed, the better the results. 

Hair transplants are generally the most permanent solution to MPB and work because they take healthy follicles from the sides and back and place them in the thinning areas. MPB doesn’t affect the scalp evenly as you probably know. Most often men lose hair at the crown or their hairline starts to recede, but the back and sides continue to grow as normal. This is because the follicles in these areas are less sensitive to DHT. Their androgen receptors simply don’t respond to DHT in the same way and so the miniaturization process never takes hold. These follicles continue to work as normal and remain resistant to DHT when they’re moved to new areas. This is what makes transplants a long-lasting solution.  

Male pattern baldness is a common condition that’s primarily caused by hormones. Although it can’t be reversed, treatments can successfully slow its progression and help men restore their hair and get their confidence back.