What hormones are responsible for hair loss? Hair loss known as "Alopecia" is a common hair disorder among the mass population and it is prevalent among both genders. Hair loss although is a widely investigated and examined area of science is still not fully understood. A series of factors and reasons have been discussed in the literature that might potentially lead to partial or total hair loss from scalp or even other parts of the human body.
Majority of cases reported are characterized as “Androgenic Alopecia” which is believed to be due to genetic as well as hormonal. The male population mostly manifests this form of hair loss (Male Pattern Hair Loss, MPHL) and male reproductive hormones are involved in such a problem.
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Role of Hormones in Hair Loss
Human hair growth is regulated by the synthesis of various hormones inside our body. It is a simple observation that a newly born baby has slightly different hair density, diameter and even color. With age and time, hair color changes and so as its texture and other physiochemical properties. At puberty time, some distinct changes occur e.g. enlargement of testicles, the appearance of facial & pubic hair and voice changing. All these changes are governed by a series of complex biochemical reactions happening in our body and hormones play a vital role in all these changes. Testosterone is one of the most important hormones, particularly for males.
In the same way, scalp hair, their distribution, growth rate and the cycle is mediated by the presence of some hormones. These hormones also regulate the normal functionality of hair follicles, their health and well-being. In early studies, male reproductive hormones were highlighted playing some role in hair loss problem. Male patients having castration carried out at early childhood age did not demonstrate any androgenic alopecia upon reaching adulthood age.
However, they developed Male Pattern Hair Loss (MPHL) on treatment with testosterone. This famous observation demonstrated the function of testosterone hormone in hair loss problem. Further studies found that one of testosterone derivative (metabolite); dihydrotestosterone (DHT) is more active in hair loss. So, let study more about these two chemicals and feel free to explore some of the possible solutions below
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What is Testosterone and Dihydrotestosterone?
Testosterone is male sex hormone secreted by primarily by testicles of male individuals and to some extent by ovaries of females. It is known to induce various characteristic changes in growing kids when they get to puberty age (as mentioned above). Abnormal (hypo or hyper) secretion can cause significant changes in male physical, physiological as well as sexual patterns of an individual.
Dihydrotestosterone (DHT) is the metabolic derivative of testosterone produced inside our bodies following complex biochemical reactions. The conversion of testosterone to dihydrotestosterone is catalyzed by a special enzyme called 5-alpha reductase (5α-R). It takes place in the prostate gland, seminal vesicles, brain tissues, skin dermis and hair follicles. It is now known that there are two types of 5α - R enzymes. Type I is found predominantly in scalp skin, sebaceous glands, chest/back skin, liver, adrenal gland, and kidney, whereas Type II has been specifically localized within the hair follicle itself, in the innermost layer of the outer root sheath and is responsible for the dihydrotestosterone conversion in hair follicle.
Interestingly, studies have revealed the male patients without any Male Pattern Hair Loss (MPHL) do have a deficiency of Type II 5α-R enzyme. This means, hair loss is regulated and controlled by the availability of this enzyme and its catalysis to convert testosterone into dihydrotestosterone.
Changes in the hair follicle with fluctuating hormone level
Hair growth & loss both depend upon biochemistry of hair follicle from where hair originates. Thus all the changes leading to hair loss takes place in hair follicle. We may call it a unit place where all these chemistries are happening. Inside follicle, dihydrotestosterone alters the hair cycle known as “Follicle Miniaturization”. High levels of dihydrotestosterone may shrink hair follicle and shorten hair cycle leading to growing hair thinner and more brittle which eventually fall out quickly.
It may also slow down the growth of new hair from follicle once old hairs are shed delaying the whole biological process of the hair life cycle. In both mechanisms, the result is the same, hair loss. That's why besides the fact that androgenic alopecia is considered genetic, hormones act as a fundamental game-changer influencing the ultimate lifestyle of that person.
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What should we do to avoid hormone-induced hair loss?
Everything has a solution, we try different steps to minimize the impact by following the steps below:
- Proper diagnosis to make sure the nature of the problem to design a remedy
- Avoid hair care products likely to damage scalp/hair e.g. once you have been diagnosed with alopecia, please avoid using harsh chemical treatment e.g. hair bleaching, coloring, relaxers and perms.
- In terms of medication, the key is to control the catalytic conversion of testosterone into dihydrotestosterone using the 5α-R enzyme. So, if we can control this biochemical reaction by inhibiting the activity of this enzyme, we can avoid or at least minimize hair loss.
- About this, there are currently two FDA approved medications, Finasteride using orally and Minoxidil topically applied at the scalp. However, it must be kept in mind, these topical medications work only where the medication is applied; therefore, the entire area at risk of loss (the top of the scalp) should be treated with a given topical agent.
- Treat any underlying scalp disorder such its seborrheic dermatitis or scalp psoriasis as these conditions can affect the ability to use topical treatments for hair loss without irritation.
- Any other medication that may cause hair loss should be stopped immediately with the consultation of your doctor.
Summary and Conclusion
Hormonal changes in our body have a great impact on the health of our hair. Testosterone and its metabolism can accelerate hair fall quite drastically. Although the genetic aspect of hair loss is still not fully understood, the role of dihydrotestosterone in male pattern hair loss (MPHL) is well documented. This has guided to develop treatments and remedies to avoid hair loss and combat this problem.
Bibliography & Further reading:
- Zviak, C., The Science of Hair Care. Taylor & Francis: 2005.
- Marsh, J. M.; Gray, J.; Tosti, A., Healthy Hair. Springer International Publishing: 2015.
- Olsen, E. A.; Messenger, A. G.; Shapiro, J.; Bergfeld, W. F.; Hordinsky, M. K.; Roberts, J. L.; Stough, D.; Washenik, K.; Whiting, D. A.
- Evaluation and treatment of male and female pattern hair loss. J. Am. Acad. Dermatol. 2005, 52 (2), 301-311.
- Whiting, D. A., Male pattern hair loss: current understanding. Int. J. Dermatol. 1998, 37 (8), 561-566.
- Gummer, C. L., Cosmetics and hair loss. Clin. Exp. Dermatol. 2002, 27 (5), 422-425