Androgenetic Alopecia - AGA

Hair loss can result from many factors. Some of these include thyroid disorders, high fever, diet, childbirth, and certain medications. The most common form of scalp hair loss is termed Male Pattern Baldness ( MPB ) or Androgenetic Alopecia ( AGA ). This type of hairloss is NOT caused by poor circulation, clogged hair follicles, frequent shampooing, or the use of hats or helmets. 95% of hair loss in men and 65% in women are from AGA. There is no actual hair shedding. The characteristic feature is hair miniaturization in patterned areas

Patterned Hair Loss

AGA has 2 common patterns: Receding hairline and thinning crown. AGA is determined by a combination of hereditary factors and male hormones called androgens which include testosterone and dihydrotestosterone ( DHT ). The tendency for male and female pattern hair loss is genetically inherited from either side of the family and begins to develop after puberty. Hair on the scalp that is genetically affected by DHT (generally the front and top of the scalp), starts to shrink until it is lost. Whereas hair at the back and sides of the scalp is permanent because it is not affected by DHT.

5 Important Points about AGA

•   AGA causes 95% of all hair loss in men, followed by Alopecia Areata (1-2%)
•   AGA progresses with age
•   AGA is unpredictable
•   You may be the first one with AGA in family
•   There is no actual loss of hair follicles

Incidences of AGA in Men

•   19.9% of Chinese have AGA
•   About age 21, 25% of men with AGA first notice hair loss
•   About 25% by age 25-30 will have AGA
•   About 40% by age 40 will have AGA
•   About 50% by age 50 will have AGA

1. Normal hair

2. Early stage of Miniaturization

3. Intermediate stage - 50% hair affected

4. Progression - 75% hair affected

5. Advanced stage - mini-hairs invisible

6. Only vellus hairs remain

7. Under magnification the hair follicle orifices are still clearly visible

•   The presence of "mini-hair" is diagnotic of androgenetic alopecia
•   Miniaturization is from DHT acting upon androgen-sensitive hair follicles
•   The diameter of the hair shaft is diminished with time
•   Our human eyes can only see hair larger than 0.02mm in diameter
•   Actual number and density of all hairs (including mini-hairs) remain unchanged
•   Truely speaking there is no actual loss of hair
•   Under magnification one can still see all the hair follicle openings
•   Hair loss treatment reverses miniaturization rather than grows new hair

(Picture Above) Binding DHT with Androgen Receptor in the hair follicle induces Miniaturization. (source)

Androgen Receptors (AR)

AR protein mediates the action of androgens (male hormones) including testosterone (T) and DHT. Once activated by an androgen it translocate into the nucleus of a cell, where it acts as a transcription factor responsible for the transcription of other genes.

Androgen Receptor Genes

These are the DNA regulator of AR and are targeted by the HairDx Genetic Test. The genes are found in:
•   X-chromosome - the major susceptible gene for AGA
•   Several other genes e.g. the short arm of chromosome 20

Diydrotestosterone ( DHT )

DHT is a by-product of testosterone converted by Type II 5 α reductase. Although all androgens can cause miniaturization in men, DHT has highest affinity for the hair follicle Androgen Receptors. Skin and follicles in balding scalp contain more DHT than non-balding scalp. Prolonged DHT exposure leads to miniaturization.

DHT also causes acne, facial hair, and enlargement of the prostate(BPH). Kaufman in 2002 showed that DHT have no known beneficial role after puberty and can be targeted specifically without significant concern.

5 Alpha Reductase

There are 2 types of 5 α Reductase: Type I & II. Type 1 is found in all body skin and scalp, while Type II is found in genital skin, prostate, and other genital tissues. Dr Inaba suggested that 5 α Reductase is contained within the sebaceous glands of hair follicles. Over-consumption of animal fat may stimulate the sebaceous gland and thus 5 α Reductase leading to early onset of AGA. Some part of the world population has no 5 α Reductase. Consequently they have no prostate or hair loss problem.

Hair Loss Classification

The universal standard of MPB (Male Pattern Baldness) categorization was described by Dr Norwood in 1975 - the Norwood Classification. However after seeing thousands of cases, we found that many patients do not actually fit into the types. Women can have Male Pattern Baldness which is typically the receding of hairline into a M-shape. The Norwood system should be used as guideline only.

Normal Type

Type I
  •   No receding apex
•   No receding of mid-hairline
•   No loss of hair density
•   Seen in 18 - 20 of age
Type II
  •   Apex recedes less than 2.5 cm
•   Slight receding mid-hairline
•   usually seen in age 20 - 30
Type III
  •   Obvious receding apexes
•   Obvious receding mid-hairline
•   The early stage of MPB
Type IV
  •   Density falls along hairline
•   Skin is exposed in vertex
•   Thick hair remains in between
Type V
  •   Further loss of hair density
•   Minimal hair remains in between
Type VI
  •   Minimal hair from front to crown
Type VII
  •   No hair on top
•   Only rim of hair at the occipit
•   Shapes like a horse-shoe
•   Also thinning above ears

Type A Variant

The entire frontal hairline border progresses posteriorly without vertex baldness.

Type IIa
  •   Whole hairline recedes
Type IIIa
  •   Empty front 1/2
Type IVa
  •   Empty front to back
Type Va
  •   Baldness up to crown
•   Thick hair at occipit

Type Vertex Variant

Vertex baldness occurs before hairline recedes.

Type III Vertex
  •   Thinning starts at top
•   Hairline later recedes

Male Pattern - Receding Hairline

Female Pattern - Thinning Top


Female Pattern Hair Loss (FPHL) is a form of androgenetic alopecia with a multi-factorial, genetically determined trait. Both androgen-dependent and androgen-independent mechanisms plus a biologically normal aging process is involved. Female and male members of the family may both be affected.
Majority has normal type II 5-α reductase levels and normal DHT level in scalp skin. Elevated androgen level were seen in 16% of women with hair loss alone, and 79% if associated with hirsutism or menstrual disturbance. Though not as common, men can have Female Pattern Hair Loss when thinning extends from the centerline sideway.

There are 3 major patterns in female Pattern Hair Loss:
Type 1. M-Shaped or high forehead - Norwood's Classification
Type 2. Thinning at the centerline, extending sidway - Ludqig's or Centrifugal Classification
Type 3. Christmas Tree Pattern - Olsen's Classification

Type 1: Norwood's Classification

•   Born with a high forehead or M-shaped hairline
•   Thinning of the hairline and the crown similar to men with aging
•   Classification is by the Norwood System similar to men

Type 2: Ludwig's Classification

•   Central and possibly lateral thinning with sparing of the hairline
•   Classification is by the Ludwig System

Type 3: Olsen's Classification

•   Accentuation of frontal Loss breaching the frontal hairline
•   The loss is widest in front tapering towards the crown
•   Classification is by the Olsen's System

Treatment of Androgenetic Alopecia

Over the years there has been a marked increase in the number of products being promoted as solutions to Androgenetic Alopecia (AGA). So far there are 3 medically proven methods of dealing with hair loss: medication, low level laser therapy, and hair transplantation. Amongst these surgical hair transplantation is the only one that provides a permanent solution. The rests require continued use to become and remain efficacious; once discontinued, hair loss ensues.

Despite the availability of these proven methods, there is an enormous segment of the public suffering from hair loss who try unproven hair loss remedies. Numerous products claiming to be “natural,” “safe,” “drug free,” and effective against hair loss are heavily marketed in the media. These products could not offer clinical statistics to substantiate their claims and, eventually, the Federal Trade Commission (FTC) stepped in to regulate these products. These natural, safe, and effective solutions for hair loss are usually not what they claim, and some may secretly contain medical drugs.

In summary people with thinning hair now have more available options. Other than pills and lotions, cosmetic enhancers such as colored creams, sprays, and powders can be applied to camouflage the thinning areas. Hairpieces and weaves are other non-surgical means to cover bald scalp areas. Still, hair restoration surgery offers the only permanent, living solution.


Moderately effective medical treatments are now offered in the form of a pill and a lotion. There are only 2 drugs approved by FDA. These drugs reverse or inhibit hair miniaturization in 2 ways:
•   By Stimulating Hair Growth, or
•   By Blocking the Action of DHT

The efficacy of these drugs is more in the crown, not so much in restoring the hairline. Merck Study in 2002 showed that after 2 years of use, only 21% showed a mild improvement in the front. Nevertheless medication must be taken for life. All beneficial effect is lost once the drug is stopped. A lot of money has been invested in researches looking for the magic bullet. Success depends on early intervention and continuation of treatment. Once the hair diameter falls below 0.04mm, it cannot be rescued.

Low Level Laser Therapy

Laser Therapy, also referred to as Low Level Laser Therapy (LLLT), cold laser therapy, photobiomodulation, biostimulation, and phototherapy, has been shown in thousands of peer-reviewed publications to increase cellular survival, proliferation and function. LLLT is able to stimulate and preserve hair follicles in patients with androgenetic alopecia and other hair loss disorders. LLLT has been used over the past few years in a number of laser devices (combs, caps, hairdryer-like) for treatment of genetic or acquired hair loss... Read More

Hair restoration surgery offers a permanent, living solution to lost scalp hair. Reasonable improvement can be achieved even after a single procedure. There is no maintenance cost and no hindrance to the enjoyment of all kinds of daily leisure, sport, adventure, and intimacy.70% of men of all age can consider hair transplant. Virtually all with less than AGA Class VII can expect good result. No age limit for hair transplant as each case must be assessed individually

Should I Consider Hair Transplant?

Hair transplants is the best option to fill-in the front hairline; and to thicken the front half of the scalp. Medical treatments can be combinedd to maintain hair behind the transplants and to possibly enhance the long-term results of hair restoration surgery. Your hair restoration surgeon will work with you to design an individualized plan to fulfill your specific needs.

What Age Should I Have Hair Transplant?

Patients may have hair restoration surgery at any age. It is often better to consider hair transplant when you are not completely bald so that you can use existing hair to help camouflage the effect of the procedure. However, because hair loss tends to be both gradual and progressive, it is often unwise to start surgical treatment in a patient who is very young. Medical treatments may be offered to men with mild to moderate hair loss to help preserve thinning hair in the crown.