education image

Hair Loss In Men

Causes of hair loss in men

 

The Mechanism of Male Hair Loss: DHT

 DHT causes “miniaturization” of hair follicles

Hereditary hair loss in men (androgenetic alopecia) is caused by the action of the hormone dihydrotestosterone (DHT) on genetically susceptible scalp hair follicles.

Normally, hair follicles cycle through a growth stage (anagen), which lasts 2-6 years, and a resting stage (telogen), which lasts approximately 1–4 months. However, prolonged exposure to DHT causes genetically susceptible follicles to gradually spend less time growing and more time in the resting stage. The follicles become progressively smaller, in what is called “miniaturization,” and this causes them to produce smaller and smaller hair shafts. Eventually, they stop producing hairs completely, leaving a bald area.

DHT-sensitive follicles normally reside in the front, top, and crown of the scalp. When a sufficient number of follicles in these areas are miniaturized, the balding exhibits an easily identifiable pattern that is described by the Norwood Classification of male hair loss. Balding typically begins with recession of the hairline at the temples and thinning of the crown. It may progress to complete baldness in the front, top, and crown of the scalp while leaving a wreath of hair around the back and sides of the scalp. This area, which consists of large numbers of DHT-resistant follicles, is often referred to as the “permanent zone.”

Balding: Genes, Hormones & Age

While the cause of androgenetic hair loss is the same for all men (i.e., men whose hair loss is not caused by an underlying medical condition, drugs, or stress), there is significant variation in the age at which men start to go bald, as well as the extent of their balding. This wide variability is due to the fact that the expression of androgenetic hair loss is significantly affected by three related factors: genes, hormones, and age.

Let us explore each of these important contributors to male hair loss.

Genes in Hair Loss

Many people have heard that “hair loss comes from the mother’s side of the family,” but this is largely a myth: while there is a slightly higher frequency of inheritance from the mother’s side, male pattern hair loss is a genetic trait that can be inherited from either parent. Research suggests that it is a polygenic trait, involving more than one gene, and it is much more complicated than originally thought.

A little background on genetics: a gene is one small part of the chemically encoded hereditary instruction manual that consists of 23 different pairs of chromosomes. It is found in every cell of our body. Twenty-two of the pairs are called “autosomes” and the 23rd pair is a pair of sex chromosomes (the X or Y chromosome). In men, the sex chromosomes include an X chromosome and a Y chromosome, while in women the pair consists of two X chromosomes. These genetic instructions control everything from the development of a fetus to the color of your eyes. Genes may be “dominant,” in that the gene only needs to be present in one chromosome of a pair for the trait to show up, or “recessive,” in which the gene must be present in both chromosomes for that gene to be activated or “expressed.” The most important genes involved in androgenetic alopecia are felt to be dominant ones. It is felt that the genes governing common baldness are both sex-linked and autosomal.

 An important androgen receptor gene is located on the X chromosome

Inheritance from the maternal side of the family may be slightly more common due to the presence of an important androgen receptor gene (AR) on the X chromosome. The Y chromosome is not believed to contain any genes that affect hair loss. Inheritance from the father’s side would be explained by the presence of an autosomal (non-sex) gene, but this gene has yet to be discovered.

Complicating the issue further, just having the genes for baldness in your genetic makeup, does not guarantee that the trait will manifest. The baldness genes need to be “turned on” or “expressed” in order for androgenetic alopecia to be apparent. Gene expression is related to a number of factors, the major ones being hormones and age, although stress and other factors can contribute to hair loss in some individuals.

It is of interest that, although genes for some types of hair loss have been mapped, the genes responsible for male pattern baldness have yet to be fully identified. This suggests that any kind of genetic engineering to prevent common baldness is still many, many years away.

In summary, Androgenetic alopecia is felt to be a “dominant” genetic trait that is passed down from your mother or father, but with a slight predisposition to the maternal side due to the presence of an important androgen receptor gene on the X chromosome. In order for hair loss to become apparent, the trait must be expressed – through changes in the production of hormones or changes due to the aging process.

Hormones in Hair Loss

Hormones are biochemical substances produced by various glands located throughout the body. These glands secrete hormones directly into the bloodstream, spreading the chemicals throughout the body. Hormones are very powerful; minute amounts can have profound effects on your body.

Read about the discovery of the relationship between testosterone and hormonally-induced hair lossTestosterone, the major male sex hormone, and other hormones that have masculinizing effects are made primarily in the testicles. It is not until after the testicles develop and enlarge during puberty that hormones can reach a level in the bloodstream sufficient to commence the balding process. In addition to the testicles, the adrenal glands, located above each kidney in men and women, produce androgenic hormones. In females, the ovaries are an additional source of hormones that can affect hair growth.

 3-D model of the hormone Dihydrotestosterone (DHT)

The hormone felt to be directly involved in androgenetic alopecia is a derivative of testosterone called dihydrotestosterone (DHT). DHT, formed by the action of the enzyme 5-a reductase on testosterone, binds to special receptor sites on the cells of genetically susceptible hair follicles causing miniaturization and eventual balding. (See the Miniaturization graphic).

In men, 5-a reductase activity is higher in the balding area, which leads to the development of patterned hair loss. It typically begins with a recession of the hairline and temples and/or thinning in the crown. It can start as early as adolescence or it can appear later in life. 5-alpha reductase Type II, the predominant form in hair follicles, is blocked by the hair loss medication finasteride (Propecia). The chemical finasteride binds to 5-alpha reductase molecules, preventing them from converting testosterone into DHT. The resulting decrease in the concentration of DHT results in the halting or reversal of the miniaturization process.

It is interesting to consider that while scalp hair growth is not dependent on androgens, scalp hair loss is androgen dependent.

Age in Hair Loss

 Incidence of Male Pattern Baldness by Age[1]

Genes and hormones are not sufficient on their own to cause baldness. Even after a person has reached puberty, susceptible hair follicles must continually be exposed to DHT over time for hair loss to occur. The age at which these effects manifest varies from one individual to another and is related to a person’s genetic composition, the level of testosterone in the bloodstream, and the follicular sensitivity to the hormone.

Additionally, male hair loss does not occur all at once or in a steady, straight-line progression. Instead, it is characteristically irregular, with people losing their hair in alternating periods of slow and rapid hair loss, interspersed with periods of stability. The reasons that hair loss rates speed up and slow down are unknown, but we do know that with age, a person’s total hair volume will gradually decrease.

Even when there is no predisposition to genetic balding, as a man ages, some hairs in each follicular unit randomly begin to miniaturize. As a result, each group will contain both full terminal hairs and miniaturized hairs, making the area appear less full. Eventually, the miniaturized hairs are lost and the follicular units are reduced in number. In all adult patients, the entire scalp undergoes this aging process so that even the “Permanent Zone” is not truly permanent but will gradually thin, to some degree, over time. Fortunately, in most men, the permanent zone retains enough permanent hair so that hair transplantation remains a viable option for men well into their 70s.

Video: Treating Hair Loss Sufferers as Patients Not Just Candidates for Hair Transplantation

References:

      1. Norwood, O.T. Senile alopecia, in Hair Transplant Surgery, 2nd ed., O.T. Norwood, R. Shiell, eds. []

Classification of Hair Loss in Men

Norwood Classification

The Norwood system of classification, published in 1975 by Dr. O’tar Norwood, is the most widely used classification for hair loss in men. It defines two major patterns and several less common types. In the regular Norwood pattern, two areas of hair loss gradually enlarge to produce recession at the temples and thinning in the crown. These regions coalesce until the entire front, top and crown (vertex) of the scalp are bald.

Click “View Photos” to view examples of patients from that Norwood Class.

Class

Description

Image

Class I

Represents an adolescent or juvenile hairline and is not actually balding. The adolescent hairline generally rests on the upper brow crease.

Class II

Indicates a progression to the adult or mature hairline that sits a finger’s breath (1.5cm) above the upper brow crease, with some temporal recession. This also does not represent balding.

Class III

The earliest stage of male hair loss. It is characterized by a deepening temporal recession.

View Photos 

Class III Vertex

Represents early hair loss in the crown (vertex).

View Photos 

Class IV

Characterized by further frontal hair loss and enlargement of vertex, but there is still a solid band of hair across the top (mid-scalp) separating front and vertex.

View Photos 

Class V

The bald areas in the front and crown continue to enlarge and the bridge of hair separating the two areas begins to break down.

View Photos 

Class VI

Occurs when the connecting bridge of hair disappears leaving a single large bald area on the front and top of the scalp. The hair on the sides of the scalp remains relatively high.

View Photos 

Class VII

Patients have extensive hair loss with only a wreath of hair remaining in the back and sides of the scalp.

View Photos 

Browse Before & After Photos by Norwood Class

 

Norwood Class A

The Norwood Class A patterns are characterized by a predominantly front to back progression of hair loss. These patterns lack the connecting bridge across the top of the scalp and generally have more limited hair loss in the crown, even when advanced.

The Class A patterns are less common than the regular pattern (less than 10%), but are significant because when hair loss is in the front, patients can look very bald even if their hair loss is minimal. Men with Class A hair loss often seek surgical hair restoration early, as the frontal bald area is not as responsive to medication and the dense donor area contrasts and accentuates the baldness on top. Fortunately, Norwood Class A patients are excellent candidates for hair transplantation.

Click “View Photos” to view examples of patients from that Norwood Class.

Class

Description

Image

Class IIA

Loss of frontal hairline

View Photos 

Class IIIA

Loss of frontal hairline and front part of frontal-scalp

View Photos 

Class IVA

Loss of hair in the entire frontal scalp

View Photos 

Class VA

Loss of hair in front and mid-scalp

View Photos 

Browse Before & After Hair Transplant Photos by Norwood Class

 

Diffuse Patterned and Unpatterned Alopecia

Two other types of genetic hair loss in men not often considered by doctors, “Diffuse Patterned Alopecia” and “Diffuse Unpatterned Alopecia,” pose a significant challenge both in diagnosis and patient management. Understanding these conditions is crucial to the evaluation of hair loss in both men and women, particularly those that are young when the diagnoses may be easily missed, as they may indicate that a patient is not a candidate for surgery. (Bernstein and Rassman “Follicular Transplantation: Patient Evaluation and Surgical Planning”)

 27 Year Old Male with Diffuse Unpatterned Alopecia (DUPA)

Diffuse Patterned Alopecia (DPA) is an androgenetic alopecia manifested as diffuse thinning in the front, top, and crown, with a stable permanent zone. In DPA, the entire top of the scalp gradually miniaturizes (thins) without passing through the typical Norwood stages. Diffuse Unpatterned Alopecia (DUPA) is also androgenetic, but lacks a stable permanent zone and affects men much less often than DPA. DUPA tends to advance faster than DPA and end up in a horseshoe pattern resembling the Norwood class VII. However, unlike the Norwood VII, the DUPA horseshoe can look almost transparent due to the low density of the back and sides. Differentiating between DPA and DUPA is very important because DPA patients often make good transplant candidates, whereas DUPA patients almost never do, as they eventually have extensive hair loss without a stable zone for harvesting.

 

The progression of male hair loss in Diffuse Patterned Alopecia (DPA) and Diffuse Unpatterned Alopecia (DUPA). In DUPA, the sides thin significantly as well.

 27 y/o Son

 Densitometry

 67 y/o Father

 Densitometry

Donor area of a patient who will evolve into DUPA and whose diagnosis is not readily apparent at the age of 27.

Diagnosis of Hair Loss in Men

The diagnosis of androgenetic alopecia in men is generally straightforward. It is made by observing a “patterned” distribution of hair loss and confirmed by observing the presence of miniaturized hair in the areas of thinning. Miniaturization is the progressive decrease of the hair shaft’s diameter and length that occurs in response to androgens.

The below-left image shows a normal scalp, seen through the densitometer, in which the follicular units have full thickness, healthy terminal hairs, with hair shafts of uniform diameter. The below-right image, however, shows a scalp where the hair shafts have decreased in diameter due to miniaturization, a characteristic of androgenetic alopecia.

 

Hairs may be in varying states of miniaturization, but if the follicles are continually exposed to the hormone DHT they will eventually stop producing hairs and the follicles will disappear.

The diagnosis of androgenetic alopecia is supported by a family history of hair loss, although a positive history is not always identified, and the absence of other medical causes of alopecia. In older patients, their own history of passing through the different Norwood stages is strongly suggestive of male pattern alopecia.

Diagnosing Diffuse Hair Loss

 Dr. Bernstein Using the Video Densitometer

The diagnosis of diffuse hair loss can be more difficult because there is thinning all over the scalp rather than confined to specific areas defined by one of the Norwood patterns. However, the presence of miniaturization in the areas of thinning usually confirms the diagnosis of androgenetic alopecia.

If the diagnosis of diffuse hair loss is still unclear after densitometry, a number of other medical conditions known to cause diffuse hair loss must be ruled out, including thyroid disease and anemia. Some drugs used for high blood pressure and depression can also cause hair loss, as can anabolic steroids. When a non-androgenetic cause for diffuse hair loss is suspected, the following laboratory tests are often used to determine the cause: blood chemistries, complete blood count, serum iron, thyroid functions, and tests for lupus and syphilis.

Diagnostic Testing

When the diagnosis of androgenetic alopecia is still uncertain, further diagnostic information can be obtained from a hair-pull test, a scraping and culture for fungus, a microscopic examination of the hair bulb and shaft, and a scalp biopsy. A dermatologic consultation is warranted whenever the cause of hair loss is unclear.

Diagnosis of Hair Loss in Men

The diagnosis of androgenetic alopecia in men is generally straightforward. It is made by observing a “patterned” distribution of hair loss and confirmed by observing the presence of miniaturized hair in the areas of thinning. Miniaturization is the progressive decrease of the hair shaft’s diameter and length that occurs in response to androgens.

During your consultation, the physician assesses the degree of miniaturization using a hand-held instrument called a video densitometer. This instrument magnifies a small area of the scalp where the hair has been clipped to about 1mm in length.

The below-left image shows a normal scalp, seen through the densitometer, in which the follicular units have full thickness, healthy terminal hairs, with hair shafts of uniform diameter. The below-right image, however, shows a scalp where the hair shafts have decreased in diameter due to miniaturization, a characteristic of androgenetic alopecia.

 

Hairs may be in varying states of miniaturization, but if the follicles are continually exposed to the hormone DHT they will eventually stop producing hairs and the follicles will disappear.

The diagnosis of androgenetic alopecia is supported by a family history of hair loss, although a positive history is not always identified, and the absence of other medical causes of alopecia. In older patients, their own history of passing through the different Norwood stages is strongly suggestive of male pattern alopecia.

Diagnosing Diffuse Hair Loss

The diagnosis of diffuse hair loss can be more difficult because there is thinning all over the scalp rather than confined to specific areas defined by one of the Norwood patterns. However, the presence of miniaturization in the areas of thinning usually confirms the diagnosis of androgenetic alopecia.

If the diagnosis of diffuse hair loss is still unclear after densitometry, a number of other medical conditions known to cause diffuse hair loss must be ruled out, including thyroid disease and anemia. Some drugs used for high blood pressure and depression can also cause hair loss, as can anabolic steroids. When a non-androgenetic cause for diffuse hair loss is suspected, the following laboratory tests are often used to determine the cause: blood chemistries, complete blood count, serum iron, thyroid functions, and tests for lupus and syphilis.

Diagnostic Testing

When the diagnosis of androgenetic alopecia is still uncertain, further diagnostic information can be obtained from a hair-pull test, a scraping and culture for fungus, a microscopic examination of the hair bulb and shaft, and a scalp biopsy. A dermatologic consultation is warranted whenever the cause of hair loss is unclear.

Treatment of Hair Loss in Men

Hair loss can be treated both medically and surgically. Surgical techniques include Follicular Unit Hair Transplantation (FUT), performed though the microscopic dissection of a donor strip, and Follicular Unit Extraction (FUE), where follicular unit grafts are removed directly from the donor area through tiny round incisions. The latter procedure is now performed robotically (R-FUE).

There are two FDA approved medications for hair loss; the oral medication Propecia (finasteride) and topical Rogaine (minoxidil). Other medical therapies include Low Level Laser Therapy (LLLT) and Platelet Rich Plasma (PRP).

If you are interested in treating your hair loss, the necessary first step is to have a Physician Consultation with a board certified Bernstein Medical physician.

Surgical Hair Restoration

 Patient VSJ: before surgery (left); after hair transplant of 1,981 grafts (right). Click for more examples.

In hair transplant surgery, hair is harvested from the donor area or “permanent zone,” in the back and sides of the scalp, and then implanted into recipient sites made in the balding areas. Hair follicles from the donor area are genetically resistant to the miniaturizing effects of DHT and maintain this resistance after being transplanted. This is why the cosmetic benefits of a hair transplant are long-term.

The modern hair transplant techniques of Follicular Unit Transplantation (FUT), Follicular Unit Extraction (FUE), and Robotic Hair Transplantation (R-FUE, or Robotic FUE) were pioneered by Dr. Bernstein and are now performed by hair transplant surgeons around the world. These procedures, which produce completely natural results, are minimally-invasive and require only local anesthesia. They allow the patient to resume his or her normal activities after a brief recovery period.

 

Follicular Unit Transplantation (FUT)

 Follicular Unit Transplantation

Follicular Unit Transplantation (FUT) was first described in medical literature in a landmark publication by Dr. Bernstein in 1995.

In FUT, a strip of hair and skin, called the donor strip, is surgically removed and dissected into naturally occurring follicular units containing from one to four hair follicles. These are implanted in the balding areas where they grow permanent hairs.

FUT generally allows the surgeon to obtain a greater number of follicular units than FUE procedures. It is especially beneficial for patients who wear a longer hair style because the typically fine linear scar that results from the removal of the donor strip can easily be covered and camouflaged with hair.

Follicular Unit Extraction (FUE)

 Follicular Unit Extraction

Hair Loss Medication

The primary medications used to treat hair loss in men are finasteride and minoxidil. Both drugs act by reversing the miniaturization process (where hair follicles shrink and hairs become progressively finer until they eventually disappear). While the effects are similar, the two medications work by different mechanisms, so the combination of the two will generally give the best results.

Finasteride

 Treatment with only finasteride: before (left); after (right)
 Treatment with only minoxidil: before (left); after (right)
 Treatment with both finasteride and minoxidil: before (left); after (right)

Propecia is the brand name of the oral medication finasteride 1mg. Finasteride also comes in 1mg and 5mg generic tablets.

Finasteride blocks the enzyme 5-alpha reductase Type II from converting testosterone into dihydrotestosterone (DHT), the hormone most responsible for miniaturization, the process that leads to baldness.

As a result of blocking DHT production, finasteride enables follicles to continue to produce healthy, thick terminal hairs. Propecia, introduced in late 1997, continues to be the most effective medication for re-growing hair.

Minoxidil

Rogaine, the brand name of the topical medication minoxidil, counteracts the miniaturizing effects of DHT by lengthening the growth phase of the hair cycle, called anagen. As a result, follicles continue to produce healthy terminal hairs.

Rogaine was introduced as a hair loss treatment in 1982. While it is typically effective in blocking miniaturization in its early stages, it is not as effective as oral finasteride in this regard. Minoxidil is available as a 5% solution, 5% foam, and a 2% formulation (for women). Although the 5% solution is the most effective, it contains propylene glycol which makes it greasy and occasionally irritating to the scalp.

Other Medical Therapies

Low Level Laser Therapy (LLLT)

Low-Level Laser Therapy (LLLT) in hair restoration utilizes cool lasers to stimulate hair growth and reduce hair loss. LLLT is based on the scientific principle of photo-biotherapy which occurs when laser light increases cell metabolism and protein synthesis. Although the exact mechanism by which laser light promotes hair growth is still unknown, it appears to stimulate the follicles on the scalp by increasing energy production and reversing miniaturization.

Recent studies have shown that Low Level Light Laser Therapy (LLT) appears about equal to the benefits of the hair loss medication minoxidil used over the short term. At present, its long-term benefits are less clear.

Platelet Rich Plasma (PRP)

Platelet Rich Plasma (PRP) is concentrated blood plasma containing approximately five times the number of platelets found in normal circulating blood. In addition, it contains biologic growth factors and other bioactive proteins that aid in wound healing and possibly hair growth. Recently, studies have suggested that PRP may serve as a safe and effective treatment option for common genetic hair loss.

In the medical treatment of male pattern baldness (androgenetic alopecia), PRP can be injected into the balding scalp to potentially stimulate thin (miniaturized) hair to grow into thicker (terminal) hairs. Patients with thinning, but not totally bald, areas would be the best candidates.

website logo footer

Confidence Awaits

info@hairlosssolutionsmoncton.com

21 Austin St, Moncton, NB, E1C1Z7