Causes of hair loss

To understand the different types of hair loss in women, and their management, it is helpful to divide the patterns into 2 categories:

A) Localizes hair loss

Localized hair loss may be sub-divided into scarring and non-scarring types. Alopecia Areata is a genetic, auto-immune disease that typifies the non-scarring type. It manifests itself with the sudden onset of round patches of hair loss associated with normal skin and can be treated with local injections of Corticosteroids. Hair Transplantation is not helpful for this type of Hair Loss.


Alopeci Areata

Scarring Alopecia can be caused by a variety of medical or dermatologic conditions such as Lupus and Lichen Planus, local radiation therapy, injuries, or from local medical problems. Once the active process of Alopecia have been cured, It is usually amenable to Hair Transplantation.

Scarring Alopecia

Localized hair loss that occurs around the hairline after face-lift surgery may be permanent as can Traction Alopecia, the hair loss that occurs with constant tugging on the hair. Both of these conditions can be treated with Hair Transplantation.

B) Male pattern baldness

The most common type of baldness in men is called Male Pattern Baldness or more scientifically, Androgenetic Alopecia. In Androgenetic Alopecia, hair follicles that are producing healthy, terminal hairs begin to produce thinner, shorter, more brittle hairs with weaker shafts (this process is called Miniaturization and the hairs involved are called Miniaturized hairs). Eventually, these follicles produce only fine, almost invisible, short, vellus hairs, or they may die out altogether.

Androgenetic hair loss is caused by the effects of male hormones on genetically susceptible hair follicles. It is related to three interdependent factors:


Common baldness cannot occur without the presence of specific inherited genes. These genes can be passed on by either parent. A gene is a single bit of chemically encoded hereditary instruction that is located on a chromosome and actually represents a tiny segment of DNA. Chromosomes occur in pairs (humans have 23 pairs), and every individual gets one set of chromosomes from each parent. The genetics of androgenetic alopecia is complicated and hair loss is now felt to involve more than one gene. When several genes govern a trait, it is called polygenic.

Genes that are located on the X or Y-chromosomes are call sex-linked. Genes on the other 22 pairs of chromosomes are called autosomal. It is felt that the genes governing common baldness are autosomal. This means that the baldness trait can be inherited from the mother’s side of the family or the father’s side. The commonly held notion that baldness comes only from the mother’s side of the family is incorrect, although for reasons not fully understood, the predisposition inherited from an affected mother is of slightly greater importance than that inherited from an affected father.

The term, “dominant” means that only one gene of a pair is needed for the trait to show up in the individual. A “recessive” gene means that both genes need to be present in order for the trait to be expressed. The genes involved in androgenetic alopecia are felt to be dominant.

Just because a person has the genes for baldness, doesn’t mean the trait will manifest itself. The ability of a gene to affect one’s characteristics, i.e. be visible in a particular individual, is called “expresivity”. Gene expression is related to a number of factors, the major ones being hormones and age, although stress and other factors can play a role. To put it simply, a man whose father and uncles are severely bald may have minimal hair loss himself, either because the baldness genes have not been passed on or because the expression of the baldness gene that he did inherit is limited.

It is of interest that, to date, none of the genes for male pattern baldness have been identified. This suggests that any kind of genetic engineering to prevent common baldness is still many years away.


Hormones are biochemical substances that are made in various glands throughout the body. These glands secrete their products directly into the bloodstream so that the chemical they make is spread throughout the body.

These chemicals are very powerful; only minute amounts of them have profound effects upon the body. The major male sex hormone is called testosterone. Testosterone and other related hormones that have masculinizing effects are made primarily in the testicles, therefore, the hormonal levels that are seen in adults do not reached significant levels until the testicles develop and enlarge during puberty. In fact, these same hormones are the cause of many of the changes that occur in puberty; change in the voice, growth of the beard and mustache, development of an adult aroma in the sweat, change in the muscular development, and change in the basic body shape.

These same hormones that cause acne and beard growth can also signal the beginning of baldness. The presence of androgens; testosterone, and its related hormone DHT, cause some follicles to regress and die. In women, hormones with androgenic activity cause hair loss as well. In addition to the testicles, the adrenal glands located above each of our kidneys, produce androgenic hormones, and this would be similar in both sexes. In females, the ovaries are an additional source of hormones that can affect hair.

The specific relationship between testosterone and hormonally induced hair loss was discovered by a psychiatrist early in this century. At that time, castration was commonly performed on patients with certain types of mental illness. The rationale behind this procedure was that it was believed to be a treatment for mental illness at a time when there were no other forms of real treatment. Castration seemed to have a calming effect upon many patients and castration reduced the sex drive of patients who had no outlet for their desires. The doctor noted that the identical twin brother of one patient was profoundly bald while the mentally ill twin had a full head of hair. The doctor decided to determine the effect of treating his patient with testosterone, which had recently become available in a purified form. He injected his patient, the hairy twin, with testosterone to see what would happen. Within weeks, the hairy twin began to lose all but his wreath of permanent hair, just like his normal twin. The doctor, then, stopped giving the testosterone to see whether the process would be reversed, but the balding process continued and his patient never regained his full head of hair. It was apparent to him that eliminating testosterone will slow, or stop, further hair loss once it has begun, but it will not revive any dead follicles.

The hormone felt to be directly involved in androgenetic alopecia is actually Dihydrotestosterone (DHT) rather than testosterone. DHT is formed by the action of the enzyme 5-a reductase on testosterone. DHT acts by binding to special receptor sites on the cells of the hair follicles to cause the specific changes associated with balding. Among other effects, DHT decreases the length of the anagen (growing) cycle, and increases the telogen (resting) phase, so that with each new cycle the hair shaft becomes progressively smaller.

It is interesting that testosterone effects axillary and pubic hair, whereas DHT effects beard growth, patterned baldness and the appearance of hair in the nose and ears (something that older men experience). Scalp hair growth, however, is not androgen dependent, only scalp hair loss depends on androgens.

In men, 5-a reductase activity is higher in the balding area. This is the enzyme that is inhibited by the hair loss medication finasteride. Women have ½ the amount of 5-a reductase overall as compared to men, but have higher levels of the enzyme aromatase, especially in their frontal hairline. Aromatase decreases the formation of DHT, and its presence in women may help to explain why the presentation of hair loss in women is different than in males.

One should keep in mind that the presence of the necessary genes and hormones are not, in themselves, sufficient to cause baldness. The reaction also requires time of exposure of susceptible hair follicles to the hormone for hair loss to begin. The time required for this to start varies from one individual to another and is related to a person’s genetic expression and to the levels of testosterone in his bloodstream.

There is another time factor that is poorly understood. Hair loss does not occur all at once nor in a steady, straight-line progression. Hair loss is cyclical. People who are losing their hair experience alternating periods of slow and rapid hair loss and even stability. Many of the factors that cause the rate of loss to speed up or slow down are unknown.


The presence of the necessary genes and hormones are not alone sufficient to cause baldness. Even after a person has reached puberty, susceptible hair follicles must continually be exposed to the hormone over a period of time for hair loss to occur. The age at which these effects finally manifest themselves varies from one individual to another and is related to a person’s genetic composition and to the levels of testosterone in the bloodstream.

Hair loss does not occur all at once, nor in a steady, straight-line progression. People who are losing their hair experience alternating periods of slow and rapid hair loss and even stability. Many of the factors that cause the rate of loss to speed up or slow down are unknown, but we do know that with age, a person’s total hair volume will decrease.

Even when there is no predisposition to genetic balding, as a patient ages, some hairs randomly begin to miniaturize (shrink in length and width) in each follicular unit. As a result, each group will contain both of full terminal hairs and miniaturized hairs (similar to the very fine hairs that occur on the rest of the body and are clinically insignificant) making the area look less full. Eventually, the miniaturized hairs are lost, and the actual follicular units are reduced in number. In all adult patients, the entire scalp undergoes this aging process so that even the donor zone is not truly permanent, but will gradually thin, to some degree, over time. Fortunately, in most people, the donor zone retains enough permanent hair that hair transplantation is a viable procedure even for a patient well into his 70’s.

Assessing hair loss

The first step in making a rational assessment of the extent of your hair loss, is to compare your present hairline with the hairline on a photograph taken a few years ago. This will give you an approximate idea of how much hair loss has occurred and the rapidity of the process. The unknown factor for most men is the extent of hair loss in the crown area. Looking in a mirror is one way to appraise the loss at the back of your head. The best way to accurately assess the hair loss in this area is to have a friend take a Polaroid photo of the back of your head. For an accurate reading, the picture must be taken with a flash. Another way is to ask your barber or hairdresser.

A visit to Dr. Vafaei who is specialist in hair restoration is a worthwhile step. A thorough history and examination of the scalp can reveal the extent and trend of the hair loss process. With the use of the Hair Densitometer, a special magnifying apparatus, Dr. Vafaei can measure the actual degree of hair loss in various areas of the scalp. This has the advantage of establishing a baseline from which the hair loss can be graded over time. If you decide to treat the process with minoxidil, a repeat examination in 6-12 months may show the effectiveness of the treatment. Careful assessment of the hair loss process is critical to accurate prediction of the rate and extent of hair loss.

The scientific way to assess your degree of baldness is to compare your pattern with the standard patterns described by Dr. O’Tar Norwood. They depict the most common configurations of male pattern baldness. There are seven grades of hair loss in the main series and five grades of a variation called the “A” series. Comparing your own front and back with these diagrams can tell you where you stand now. Discussion with Dr. Vafaei can give you some idea of what is likely to be in your future.

Dr. O’Tar Norwood

Norwood Classification of hair loss

In 1975, a dermatologist and hair transplant surgeon, Dr. O’Tar Norwood, building upon the earlier work of Hamilton, developed a classification of male pattern hair loss that is widely used today. He divided androgenetic hair loss in men into two common patterns: the Regular Type, characterized by hair loss that begins in two different areas (at the temples and in the crown) and that gradually merge into one; and the less common Type A, that is characterized by “front-to-back” hair loss. Hair loss that is not genetic in origin usually follows a different pattern.

Some women also lose hair according to the pattern described by Norwood, but more commonly have a diffuse (thin all over), rather than patterned variety (please see Hair Loss in Women).

Hair loss tends to progress over the years, although the rate can vary dramatically from person to person and the rate of loss can vary significantly over time. For example, a man may loose hair rapidly in his early 40’s and then stabilize for many years, not showing a significant amount of additional hair loss until his 60’s. People who become extensively bald usually, but not always, show a significant amount of hair loss in their 20’s.

In general, the pattern of one’s hair loss follows the specific type first presented. For example, a person who begins as a Class 3 usually evolves into a Class 4, then a Class 5, etc.. A Class 3a becomes a Class 4a and then a Class 5a. Less commonly a Class 2 may thin diffusely and directly evolve into a Class 6 or 7. We call this later process Diffuse Patterned Alopecia.

Look over the following diagrams and their explanations to see if you can recognize your pattern or the pattern of hair loss of any male member of your father’s or mother’s side of the family. The patterns you see in your older relatives may become your pattern since heredity plays an important role in androgenetic baldness. It is important to note the age at which the family member reached a specific pattern. For example, if your father is totally bald, but lost all of his hair in his twenties, and you are 35 with a full head of hair, his pattern has little relevance to predicting your future loss.

Once you have identified your Norwood Class, view our photo galleries to view before and after photos of actual patients.

A) Regular Norwood classes

  • No recession
  • “Adolescent” or “Juvenile” hairline
  • No recession
  • “Adolescent” or “Juvenile
  • Further frontal recession
  • Deeper recession at corners
  • Earliest stage of balding
  • Further frontal recession
  • Deeper recession at corners
  • Earliest stage of balding
  • Further frontal hair loss and temporal recession
  • Enlargement of vertex (crown)
  • Solid band of hair across top separating front from vertex
  • Frontal and temporal areas enlage further
  • Band separating the two areas becomes narrower and sparser
  • Frontal and vertex balding areas merge into one and increase in size
  • Narrow horseshoe band of hair
  • Low hairline in the back
  • Hair in permanent zone may be sparse

B) Type A variant Norwood classes

A) Frontal recession keeps advancing backwards
B) Single area of balding
C) Eventual extent of balding tends to be more limited than in Regular classes

Entire frontal hairline recedes

Hair loss moves past this “mid-coronal” line

Hair loss extends towards the vertex
Back part of bald area is narrower than in the regular Norwood VI

How much hair do I need?

Over the past few years, we have tried to put a number on the amount of hair and grafts any given person might need. As we have gained experience, we have found that our patients want more hair than we had believed. At our center, patient procedures are planned to ensure natural looking results after each session. However, some of our patients elect to undergo further sessions to further enhance their appearance. A recurring question is how much hair does Dr. Vafaei recommend? The number of grafts recommended is highly dependent on information we would gather during a private consultation with you, as well as the characteristics of the hair-coarseness, texture, etc.

The total number of follicular units generally transplanted in the first session for specific Norwood classifications are listed in the table below. In general, the higher the donor density, the greater the number of hairs each follicular unit will contain. With low donor density, little scalp laxity or poor hair characteristics, these numbers may not be achievable.

The number of grafts that can be harvested for any individual is limited by the laxity of the scalp and the density of the hair. In some individuals, it will be impossible to safely move 5000 or more grafts over the individual’s lifetime, while in other individuals, the number of grafts can reach significantly above 7000.

Norwood Class Follicular Units Total Units With Crown*
3 800-1000 + ** –
3 Vertex 800-1000+ 1100-1300+
3A 1300-1600+
4 1100-1400+ 1500-1800+
4A 1700-2100+
5 1500-1800+ 1900-2500+
5A 2200-3000+
6 2000-3200+ 2800-3800+
7 2000-3500+


Befor Hair Transplantation Surgery

After Hair Transplantation Surgery

Befor Hair Transplantation Surgery

After Hair Transplantation Surgery