hair misconceptions

Does Testosterone Cause Hair Loss?

Does Testosterone Cause Hair Loss?

We’re all familiar with the concept of losing hair as we age. While some of us are able to maintain our youthful looks well into our later years, many more are forced to deal with visible signs of aging like pattern hair loss. While women can absolutely suffer from pattern hair loss as well, due to its prevalence in men it’s more commonly known as male pattern baldness, or androgenetic alopecia. Why does hair loss differ between the sexes, and could the level of hormones like testosterone play a role? Read on to find out more.

What is testosterone?

Testosterone is classified as a steroid hormone, and it serves as the prime example of a major sex hormone in males. This type of hormone is known as an androgen because of its role in the development of male physiological characteristics. While both sexes produce androgens, males produce testosterone at up to eight times the level of females. In men, most testosterone is produced in the testes, with the remainder being synthesized in the adrenal glands. In women, relatively smaller amounts of testosterone are produced in the adrenal gland as well as the ovaries; during pregnancy, testosterone can be produced by the placenta.

Testosterone isn’t just responsible for libido or the development of sex-specific organs, however. The androgen can play a key role in:

  • Muscle size, strength, and growth
  • Bone strength and growth
  • The gradual deepening of the voice during puberty
  • Wound healing and maintenance of the epidermal barrier
  • Growth of the sebaceous glands
  • The development of body, pubic, and facial hair during puberty
  • The onset of pattern hair loss
testosterone in the bloodstream

How does testosterone reach the skin and the hair follicles, and how does it have an impact?

When signaling molecules like testosterone are secreted, they get released into the bloodstream in order to travel throughout the body and reach their targets. These targets are known as receptors, and if androgenic molecules like testosterone are the key, androgen receptors are the lock.

Not all tissues in the body contain the same amounts of these receptors, however. Think of the bloodstream like a highway full of cars, each listening to the radio station during rush hour, with each radio frequency that’s being broadcast like a particular hormone. While the air around us is full of radio waves, each car can set their radio dial to a specific frequency in order to only hear the station they want to listen to.

testosterone vs DHT affinity

At the same time, not every radio station signal is broadcasting at the same strength. Testosterone is just one type of androgenic signal, while the hormone dihydrotestosterone (DHT) is another. When it comes to a molecule’s affinity for binding to a receptor—in this example, the strength of the radio signal being picked up by the stereo—androgens like testosterone and DHT have different signal strengths. DHT binds to androgen receptors 2-3 times more strongly than testosterone, while also releasing from the receptors up to 5 times more slowly. Put simply, this means that while testosterone is the hormone we’re all most familiar with, when it comes to issues like hair loss that arise from molecular signaling within the hair follicle, DHT is the more impactful hormone.

How do androgens like testosterone and DHT affect hair loss?

When it comes to hair loss, the connection between hair loss and androgens like testosterone and DHT might seem unclear. We’ve focused on the hair follicle and the many stages of the hair growth cycle in previous posts. We’ve also discussed the two types of hairs, the thin, light vellus hairs vs. the coarse, dark terminal hairs.

DHT shrinks hair follicles

As the body goes through puberty, androgens signal to follicles on the body and face with vellus hairs to transition to the thicker, coarser terminal hairs. As we age past puberty, however, those androgens can have the opposite effect: testosterone and DHT can actually cause the hair follicle to shrink, causing follicles that once produced thick, coarse strands of hair on the scalp to revert to producing thinner hairs, possibly even shrinking to the point where they no longer produce strands of hair at all.

So what is DHT? Where is it produced, and how does it differ from testosterone?

You might’ve guessed from the name dihydrotestosterone, but DHT is very similar to testosterone—in fact, DHT is produced from testosterone when testosterone interacts with the enzyme 5α-reductase. There are three types of this enzyme:

  • 5α-R1: Primarily expressed in peripheral and connective tissues like the liver, skin (including the scalp), and intestines.
  • 5α-R2: Primarily expressed in sex-associated tissues like the prostate and the genitals.
  • 5α-R3: Similar to Type 1, expressed in peripheral tissues like the skin (including the scalp), brain, and mammary glands.

Why does it matter where these enzymes are produced?

If we keep using the car-and-radio analogy, once you’ve gotten the signal of the station to listen to your favorite music, what impacts how loud that music is in your car? Think of the enzymes like the speakers: More enzymes function like a surround-sound set. If the enzyme isn’t expressed, it’s like missing speakers in your system. If the enzyme is expressed, it’s like having a powerful audio system to blast your tunes.

Outside of the prostate, the scalp possesses one of the highest concentrations of 5α-reductase enzymes anywhere in the body. That means that the impact on hair loss is twofold: 

  1. When testosterone passes through the scalp as it circulates in the bloodstream, more of that testosterone will convert to DHT and remain in the scalp.
  2. The greater number of androgen receptors in the scalp will bind the even stronger DHT, accelerating the shrinkage of the hair follicle and the reversion of the hair strands from terminal hairs to vellus hairs, possibly even causing the follicle to shut down production of new hair strands entirely.
male vs. female pattern baldness

Why do men and women experience different telltale signs of pattern baldness?

You might also be wondering: If both men and women produce testosterone at different levels, why does pattern baldness look so different in men than it does in women? Shouldn’t it look the same in both, but just less severe in women?

androgen receptor density in males

As it turns out, women have 40% fewer androgen receptors in their frontal hair follicles near the forehead, as well as 3-3.5 times less 5α-reductase in those same areas. it comes to the classic presentation of androgenetic alopecia—a receding hairline, particularly around the forehead and above the temples—men are more likely to exhibit these traits than women.

How to deal with testosterone-related hair loss?

The connection between testosterone and hair loss can be complex. Let’s review:

  • Testosterone and dihydrotestosterone (DHT) are examples of signaling hormones called androgens.
  • To send their signal throughout the body, androgens bind to androgen receptors.
  • The strength of that signal depends on both the concentration of androgens, the concentration of androgen receptors, and the type and strength of the androgen binding to the receptor.
  • In the scalp, when androgens bind to androgen receptors, the hair follicle responds by miniaturizing and reducing the size of the hair strand, or in some cases ceasing activity altogether.
  • DHT:
    • Binds more strongly to androgen receptors than testosterone.
    • Is produced in greater amounts in the scalp.
  • Men:
    • Produce more androgens like testosterone than women.
    • Produce more enzymes that produce DHT from testosterone than women.
    • Possess more androgen receptors in the frontal hair follicles than women, leading to the typical presentation of androgenetic alopecia, or male pattern baldness.

Treatment options do exist for testosterone-related hair loss, however:

  • Finasteride. Commonly marketed as the brand name Propecia, finasteride addresses hair loss and other issues associated with increasing levels of DHT by inhibiting the enzyme that converts testosterone to DHT, 5α-reductase.
  • Dutasteride. Though not approved by the FDA for treating hair loss, dutasteride has been shown to be more effective at inducing hair regrowth in men than finasteride. It is currently approved for the treatment of androgenetic alopecia in South Korea and Japan, and is only available for the treatment of hair loss in the United States as an off-label prescription.

Which solution is right for you?

Finasteride and dutasteride represent powerful solutions when it comes to addressing testosterone-related hair loss. However, many potential patients that are looking to address hair loss issues are unsure about the consequences of disrupting their hormones. If that sounds like you, our Hair Revival Serum with ProCelinyl™ could be an option for you.

Profile photo for Evan Zhao

Reviewed by: Evan Zhao, PhD

Evan is a synthetic biologist and chemical engineer. He completed his BS from Caltech, and his MA and PhD from Princeton University. He received the prestigious Schmidt Science Fellowship as a postdoctoral fellow at MIT/Harvard and has published in the world's top scientific journals including Nature, Nature Biotechnology, Nature Chemical Biology, and more.

Written by: Revela Editorial Team

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