By far the most common cause of hair loss in menis androgenetic alopecia, also referred to as “male pattern hair loss” or “common” baldness. It is due to the male hormone dihydrotestosterone (DHT) acting on genetically-susceptible scalp hair follicles that causes them to become progressively smaller and eventually disappear. This process is called “miniaturization.”
This sensitivity to DHT is characteristic of hair follicles that reside in the front, top, and crown of the scalp — rather than the back and sides — producing a characteristic and easily identifiable pattern. This pattern, described by Norwood in his widely used Norwood Classification, typically begins with recession of the hairline at the temples and thinning of the crown. It may progress to total baldness, leaving just a wreath of hair around the back and sides of the scalp.
DHT is formed by the action of the enzyme 5-alpha reductase on testosterone, the hormone that causes sex characteristics in men. DHT causes male hair loss by shortening the growth, or anagen, phase of the hair cycle, causing miniaturization (decreased size) of the follicles, and producing progressively shorter, finer hairs. Eventually these hairs totally disappear (see image below).
In the following patient, we see a close-up of the side of his scalp where the hair is not affected by DHT. We see mostly groups of full thickness hairs (called terminal hairs) and a few scattered fine, vellus hairs, normally seen in a donor area. The pointer (left) indicates the location on the scalp in the close-up view.
In the area of thinning (see circle below), we see that most of the hair has been miniaturized, although all of the hair is still present.
The hairs, while still present on the scalp, are so much finer in diameter than the patient’s original hair that they give the visual appearance of thinning.
Do not use tar shampoo (a dark-colored, medicated shampoo used for psoriasis) on the transplanted area for 10 days following your procedure, as this may interfere with the growth of the grafts.
The Norwood 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 (see the chart below). In the regular Norwood pattern, two areas of hair loss–a bitemporal recession and thinning crown–gradually enlarge and coalesce until the entire front, top and crown (vertex) of the scalp are bald.
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 is the earliest stage of male hair loss. It is characterized by a deepening temporal recession.
Class III Vertex represents early hair loss in the crown (vertex).
Class IV is 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.
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.
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.
Class VII patients have extensive hair loss with only a wreath of hair remaining in the back and sides of the scalp.
The Norwood Class A patterns are characterized by a front to back progression of hair loss. Norwood Class A’s lack the connecting bridge across the top of the scalp and generally have more limited hair loss in the crown, even when advanced.
The Norwood Class A patterns are less common than the regular pattern (< 10%), but are significant because of the fact that, since the hair loss is most dramatic in the front, the patients look very bald even when the hair loss is minimal. Men with Class A hair loss often seek surgical hair restoration early, as the frontal bald area is not generally responsive to medication and the dense donor area contrasts and accentuates the baldness on top. Fortunately, Class A patients are excellent candidates for hair transplantation.
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 in 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”)
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.
As discussed in the section on the causes of hair loss in women, women’s hair loss can be classified into diffuse hair loss, localized hair loss, or patterned hair loss. It can also be divided into scarring and non-scarring types. Since the diffuse, non-scarring female hair loss caused by hereditary is so common, it has its own special classification that is based upon the degree of thinning called the Ludwig classification.
The Ludwig Classification uses three stages to describe female pattern genetic hair loss:
Type I: Early thinning that can be easily camouflaged with proper grooming. Type I patients have too little hair loss to consider surgical hair restoration.
Type II: Significant widening of the midline part and noticeably decreased volume. Hair transplantation may be indicated if the donor area in the back and sides of the scalp is stable.
Type III: A thin, see-through look on the top of the scalp. This is often associated with generalized thinning.
It is important for all women experiencing hair loss that an accurate diagnosis is made. This is particularly true when the hair loss is diffuse, as underlying medical conditions may be a contributing factor. Please refer to the diagnosis of hair loss in women page to learn about how the various types of female hair loss are evaluated.
The diagnosis of androgenetic alopecia in men is generally straightforward. It is made by observing a “patterned” distribution of hair loss (see the previous session on Classification) and confirmed by observing the presence of miniaturized hair in the areas of thinning. Miniaturization – the progressive decrease of the hair shaft’s diameter and length in response to androgens – can be observed using a densitometer, a hand-held instrument that magnifies a small area of the scalp where the hair has been clipped to about 1mm in length. Using the Electronic Hair Densitometer. The photo, below left, was taken from a normal scalp. The follicular units (groups) are comprised of full-thickness, healthy terminal hair. Note the relatively uniform diameter of the hair shafts. The photo, below right, shows that many hairs have decreased in diameter (miniaturized). This is characteristic of androgenetic alopecia.
The diagnosis of androgenetic alopecia is supported by a family history of hair loss, although a positive history is not always identified (see Genetics). In older patients, their own history of passing through the different Norwood stages is strongly suggestive of male pattern alopecia. If the hair loss is diffuse (thin all over) rather than following one of the specific Norwood patterns, the diagnosis can be more difficult. However, the presence of miniaturization in the areas of thinning usually confirms the diagnosis of androgenetic alopecia. If the diagnosis is still unclear, a number of other conditions must be ruled out.
Medical conditions that can produce diffuse hair loss in men include thyroid disease and anemia. Certain medications, including some drugs used for high blood pressure and depression, and the use of anabolic steroids, can also cause male hair loss. The following laboratory tests are often useful when a non-androgenetic cause for diffuse hair loss is suspected: blood chemistries, complete blood count, serum iron, thyroid functions, and tests for lupus and syphilis. 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.
The diagnosis of “female pattern” hair loss is relatively straightforward when there is a history of gradually thinning in the front and/or top of the scalp, relative preservation of the frontal hairline, a positive family history of hair loss, and the presence of miniaturization in the thinning areas. Miniaturization is the progressive decrease of the hair shaft’s diameter and length in response to hormones. It can be observed using a densitometer, a hand-held instrument that magnifies a small area of the scalp where the hair has been clipped to about 1mm in length. With this instrument miniaturization is easily apparent. Normally follicular units (natural hair groups) are made of full-thickness, healthy terminal hair. With miniaturization one or more hairs within each group begin to thin. Eventually these hairs are lost. If the hair loss is diffuse (thin all over) rather than in the typical female pattern on the front and top, the diagnosis can be more difficult. The presence of miniaturization in the areas of thinning usually confirms the diagnosis of androgenetic alopecia, however, if the diagnosis is still unclear, a number of other conditions must be ruled out. These have been listed in the section on Causes of Women’s Hair Loss.
Besides densitometry, two other common diagnostic tests that can be performed in the physician’s office are the hair-pull and hair pluck. In the hair pull, the physician grabs on to 20-30 hairs with his fingers and gently pulls on them. If five or more come out in the pull then this is suggestive of the increased shedding associated with telogen effluvium, a reversible type of female hair loss seen with stress, pregnancy, drug reactions and a variety of other conditions. Telogen effluvium generally occurs 2-3 months after a stressful event and affects 35-50% of one’s hair. Over 300 club hairs (telogen hairs that have rounded ends) may be shed per day.
In the hair pluck, 20 to 30 hairs are forcibly plucked from the scalp with a small clamp. The hair bulbs are then examined under a microscope to determine the ratio of anagen (growing) hairs to telogen (resting) hairs. Normally, at least 80% of the follicles should be in the anagen stage. A lower ratio would suggest telogen effluvium. With the hair pluck, various abnormalities of the hair shaft may be observed that can contribute to hair breakage and poor growth. Anagen effluvium occurs when hair is shed in its growing phase and is characterized by large numbers of tapered or broken hairs (> 80%). It can be caused by chemotherapy or radiation and can result in extensive hair loss in women.
Chronic telogen effluvium is a condition whose diagnosis is often missed, so it is worth mentioning briefly. Chronic TE affects women age 30-60. It starts abruptly with or without an initiating factor. Chronic TE presents with diffuse thinning with accentuation at the temples – often more apparent to the patient than to others. It has a long fluctuating course and patients can lose up to 50-400 hairs/day. There is increased shedding of telogen (club) hairs with a positive hair pull. Fortunately, the condition does not lead to complete baldness. Chronic TE can be expected to resolve spontaneously in 6 months to 6-7 years. When the cause of the hair loss is still uncertain, further diagnostic information can be obtained from a scraping and culture for fungus and a scalp biopsy (sent to the lab for regular and special tissue stains and examined under both horizontal and vertical sections). A dermatologic consultation is warranted whenever the cause of hair loss is unclear.
Occasionally, when a woman presents with female pattern hair loss, increased androgen production may be a contributing factor. The following signs and symptoms suggest that specific blood tests might be appropriate to rule out underlying sources of excess androgen:
It is important that when any of these symptoms are present, or these conditions are being considered, that you are under the care of a physician, to receive a proper evaluations and correct treatment if needed. Generally a gynecologist is the specialist most helpful for these problems. Some of the tests that your doctor might order when considering androgen excess include:
Other test that are commonly ordered to screen for underlying medical conditions include:
Localized hair loss in women is distinct from the diffuse thinning seen in female pattern alopecia. The following are the more common causes of local alopecia. A dermatologist should be consulted if any of these conditions are suspected. Note: the term alopecia is synonymous with hair loss).Alopecia Areata
Alopecia areata is recognized by the sudden appearance of discrete, round patches that are completely devoid of hair. Occasionally, the entire scalp may be involved (alopecia totalis) and even the entire body hair including the eyebrows and eyelashes (alopecia universalis). When localized, the lesions respond well to injections of cortisone. Generalized alopecia is more difficult to treat. The prognosis is better the older the age of onset. Alopecia areata can occasionally be associated with other conditions such as thyroid disease.Traction Alopecia
Hairstyles that exert constant pull on the hair, such as “corn rows” or tightly woven braids produce a characteristic pattern called “Traction Alopecia” that can be identified by a rim of thinning or baldness along the frontal hairline and at the temples. This is easily prevented by changing one’s daily hair-care habits, but once the hair loss occurs, it may be permanent. Fortunately, this condition is easily amenable to surgery if the cause can be eliminated.Trichotillomania
Trichotillomania is a condition seen more commonly in young females, where the person twists, tugs or pulls out her hair. This can be scalp hair, eyebrows or eyelashes. The diagnosis is made by observing short, broken hairs in the area of hair loss. The patient may deny having this habit.Face-lift & Brow-lift Procedures
Face-lift and brow-lift procedures can result in local hair loss in the vicinity of the incision. This may present as hair loss along the frontal hairline, in the temples, or adjacent to a surgical scar. If female patients do not have genetic hair loss, and have a good donor supply, they may make excellent candidates for a hair transplant.Tinea Capitis
Tinea Capitis is a fungal infection of the scalp. It presents as irregular, red and scaly patches and/or small bald patches with broken hairs. The diagnosis is made by scraping a small piece of scale from the scalp and obtaining a bit of hair for testing. The specimens are sent for special fungal stains and cultures.Pseudopalade
Pseudopalade is a non-specific scarring alopecia that generally starts on the top of the scalp and extends into the surrounding hair bearing areas with finger-like extensions. The areas look smooth and white due to the scarring and loss of hair follicles.Lichen Plano-pilaris
Lichen Plano-pilaris is an inflammatory condition of the scalp that presents with redness, scale and localized areas of hair loss. There is a characteristic scaling at the edge of each balding patch.Discoid Lupus Erythematosus (DLE)
Discoid Lupus Erythematosus (DLE) is the localized form of Systemic Lupus Erythematosus (SLE), a potentially serious autoimmune disease. The localized form presents with red, scaly, pigmented patches of scarred skin. The localized form of the disease is mostly a cosmetic problem, but patients must be evaluated for the systemic disease as well with specific blood tests such as an ANA. SLE can cause diffuse (generalized) hair loss and both the local and systemic forms of the disease may cause sensitivity to the sun.
Q: I am a 30 year old man with a balding crown. I’m 99.9% sure its male pattern baldness (I’m currently on Propecia and Rogaine). I recently read about how people going bald are getting tested for LPP (lichen planopilaris). Do you perform this test?
A: Lichen Planopilaris (believed to be a type of autoimmune disease) occurs more frequently in women than in men and more commonly in African-Americans than in Caucasians. The variation that could be confused with androgenic alopecia in men is central centrifugal cicatricial alopecia (or CCCA). While definitive testing would involve a scalp biopsy, this is rarely necessary as the doctor can easily tell by just examining you with the naked eye using magnification (densitometry).What is the Incidence of Hair Loss in Adults?
Q: How common is hair loss in adult men and women?
A: The incidence of androgenetic alopecia (common baldness) is quite high for both men and women. By age 50, 50% of men and 30% of women are affected. By age 70, that increases to 80% of men and 60% of women. Fortunately, in spite of significant thinning, women often preserve their hairline and have a diffuse pattern, so there hair loss can be camouflaged for many years.What is the Origin of the Term DUPA?
The terms DPA and DUPA were first described by O’tar Norwood in his seminal 1975 publication: Male Pattern Baldness: Classification and Incidence.What Is Saw Palmetto And Does It Prevent Hair Loss?
Q: What is Saw Palmetto?
A: Saw Palmetto is a dwarf palm plant native to North America. The active ingredients can be found in the plant’s brown-black berries. It is proposed that it blocks the enzyme 5-alpha-reductase that converts testosterone to dihydrotestosterone (DHT). There is little scientific evidence that Saw Palmetto is actually effective for hair loss.Does Sebum Cause Hair Loss By Blocking Pores On Scalp?
Q: I have been on finasteride for about 7 months. After my latest haircut I can see that my scalp is shiny. I read that is from sebum buildup and it can cause a layer that clogs the growth of hair. I was wondering if this is true and, if so, how can it be treated?
A: It is not true. Hair loss is caused by the miniaturizing effects of DHT on the hair follicle, not by blocked pores.What Happens To Hair Diameter As You Age?
Q: What happens to hair diameter when you age?
A: From infancy to puberty, hair gets progressively thicker. From adulthood to old age the hair becomes thinner again and this is exacerbated by the effects of DTH in susceptible persons. The later process is called androgenetic alopecia (common baldness) and is characterized by miniaturization – the progressive decrease in hair diameter and lengths as a result of DHT.However, even without the effects of DHT, hair gradually thins over time in many people.Is Hair Thicker In The Summer?
Q: It seems like my hair is thicker in the summer. Can this be true?
A: Hair will increase in diameter when there is more humidity, as it absorbs moisture, and will actually be thicker in the more humid summer environment.What Color Hair Is The Thickest Or Most Dense?
Q: What color hair is the thickest? I thought it was brown, followed by red then blonde? But I am also reading that red is the thickest but redheads have the fewest hairs.
A: In very general terms, the darker the hair, the thicker it is and the lower the density (hairs per area). For example, Asians have the darkest hair, the highest hair diameter and the lowest density. Scandinavian blonds have very high hair density and the fine (diameter) hair. But there are many exceptions, African Americans have black hair, but it is usually very fine and of low density. I have seen red heads in all categories.
Q: There was a retrospective study by Lotufo et al. linking male pattern baldness to heart disease. Do you think there are other links like this for androgenetic alopecia?
A: Family studies revealed both the androgen receptor locus on the X chromosome, as well as a new locus on chromosome 3q26. Association studies performed in two independent groups revealed a locus on chromosome 20 (not near any known genes) as well as the androgen receptor on the X chromosome. Read on for the rest of the answer.Is Genetic Test for Hair Loss Worthwhile?
Q: Is it worth getting the genetic test for balding?
A: You’re referring to Hair DX (hairdx.com), which costs about $150 and came to market in January of 2008 as the first test for androgenetic alopecia, aka male pattern baldness.The test screens for variations in the androgen receptor gene on the X chromosome, the gene that is associated with male pattern hair loss. The purpose of the test is to identify persons at increased risk of developing hair loss before it is clinically apparent – so that medical intervention can be started early, when it is most effective.Is Hair Loss Hereditary and are Genes Inherited from Mother’s or Father’s Side of Family?
Q: Why do some people have a full head of hair into their seventies or eighties and others start to go bald in their late teens or early twenties?
A: The cause is genetic and this poly-genetic trait can be inherited from the mother’s side, the father’s side, or both. There is an old wives’ tale that it is inherited only from the mother’s parents. Although the inheritance can come from either side, it is actually greater from the mother’s side – but only slightly.
More about Hair loss Genetics - Answers Research ConsultationBiotechnology
Is the manipulating of biological organisms to make products that benefit human beings Modern achievements include transgenics, cell cloning and the creation of monoclonal antibodies.Chromosomes
This is a single piece of DNA which contains many genes, regulatory elements and gene sequences. It is the organized structure of DNA and DNA proteins found within a cell that helps to control its functions.DNA
(Deoxyribonucleic acid) is a nucleic acid where the molecules carry genetic information within the cells. This genetic information is used in the development and functioning of all known living organisms. DNA molecule’ primary role is the long-term storage of information. These molecules contain the blueprints or instructions needed to create other components of cells.DNA Replication
The process by which chromosomes duplicate before the cells divide.Gene
A basic unit of heredity that transmits the characteristics of one generation to the next generation. Genes represent a segment of the DNA on a chromosome that determines a specific trait.Genetic Engineering
The modification of genetic material by technological means. Scientific applications may include the treatment of disease, enhancement of agriculture and manufacture of biological products.Gene Therapy
The manipulation of an individual’s genetic makeup to prevent or treat a disease. A form of therapy that attempts to fix the defective gene causing the disease.Hair Cloning
The process by which cells from a hair follicle are multiplied outside the body and then implanted in the scalp to generate new hair follicles. It is not true cloning, since cloning generally refers to the replication of an entire organism or creating an identical copy of something. With the current models of hair cloning, the cells (multiplied in tissue culture) would be used to stimulate new hair to form. This would involve some interaction with the scalp tissue and thus not produce a product identical to the original hair. More accurate terms would be hair induction or hair multiplication. These technologies are currently not available.Hair Multiplication
Process by which existing hairs are plucked from a hairy area of the scalp or body and then multiplied and implanted into the bald part of the scalp. These hairs may be separated from the shafts and cultivated in vitro (outside the body). The idea is that some germinative cells at the base of the hair follicle will be pulled out along with the hair and grow. This technology had not yet proven to be successful.Recombinant DNA
A technique to isolate and amplify genes founded by Stanley Normal Cohen and Herbert Boyer by which a synthetic DNA is created by combining one or more DNA strands and causing DNA sequences that would normally not occur together.
The ability to regrow or recreate lost or damaged limbs, tissues or organs.Regenerative Medicine
A type of tissue engineering that focuses on the use of stem cells to produce new tissue rather than by improving the function of existing tissue.Stem Cell
An undifferentiated cell from which specialized cells develop. These cells retain the ability to renew themselves through cell division, but lack the characteristics of specialized tissue.Tissue
A collection of related cells that perform a similar function in the body. Four basic tissue types include nerve, muscle, epidermal and connective.Tissue Engineering
The use of a suitable biochemical and physio-chemical factors to improve or replace the biological functions of cells. The term is commonly used for applications that repair or replace portions of or whole tissues, i.e., bone, cartilage, blood vessels.Transgene
The transference of a segment of DNA which has a gene sequence from one organism to another by any genetic engineering technique.
A meta-analysis of six studies suggests a moderate linkage between balding at the crown and heart disease. The Japanese research team that investigated the linkage suggested that more investigation be done to target the medical causes of the linkage.Early Baldness May Suggest Prostate Cancer Risk
A study of Australian men between the ages of 40 and 69 suggests that men who were mostly bald by the age of 40 were more likely to develop prostate cancer in their 50s or 60s. The Melbourne Collaborative Cohort study of about 10,000 men showed that men who have high levels of testosterone may be more vulnerable to cancerous prostate tumors.
The team of scientists that conducted the long-term study, which was published in the journal Cancer Epidemiology, Biomarkers and Prevention, reported that both baldness and prostate cancer are age-related and androgen dependent conditions, so these findings are not surprising. The statement said, “We found that baldness at the age of 40 might be a marker of increased risk of prostate cancer.”Research Points To Vitamin D Receptors As Possible Clue To Reversing Hair Loss
Could it be that Vitamin D is the cure for baldness that scientists have been looking for all these years? New research on Vitamin D, and its receptors in hair follicles, has taken us down a previously untrodden path that could, potentially, lead to new medical treatments for hair loss.
The Vitamin D receptor was previously known to stimulate hair follicles, which were in the dormant phase of hair growth, to grow hair when activated. The research into Vitamin D and its effect on hair and skin, centers around this receptor.Researchers “Accidentally” Reverse Hair Loss Caused by Stress
Sometimes an “accident” in the laboratory can lead to a remarkable breakthrough. Penicillin, Botox, Viagra, and Minoxidil — the active ingredient in Rogaine — were all unintended discoveries that led to treatments for a variety of conditions. A similar twist of fate, this time by researchers at UCLA, could lead scientists to a new hair loss treatment.Research Points to Decreased “Progenitor” Stem Cells as Cause of Male Pattern Baldness
Research published in the January 2011 issue of the Journal of Clinical Investigation (Vol. 121, issue 1) reveals another breakthrough in the medical community’s understanding of the causes of — and possible cure for — androgenetic alopecia, or common male pattern baldness. The new research shows that the presence of a certain type of cell, called a progenitor cell, is significantly reduced in men with common baldness compared to men who are not bald. Read on for more details on this breakthrough.