Androgenetic alopecia is an extremely common disorder affecting both men and women. The incidence is generally considered to be greater in males than females, although some evidence suggests that the apparent differences in incidence may be a reflection of different expression in males and females.
Male pattern hair loss (androgenetic alopecia)
Hair loss resulting in thinning is known as alopecia. When it is related to hormones (androgens) and genetics, it is known as androgenetic alopecia. When androgenetic alopecia denudes an area of the scalp it is called baldness. Male pattern hair loss is characterised by a receding hairline and/or hair loss on the top and front of the head. A similar type of hair loss in women, female pattern hair loss, results in thinning hair on the mid-frontal area of the scalp and is generally less severe than occurs in males.
What causes pattern balding?
Male pattern hair loss is an inherited condition, caused by a genetically determined sensitivity to the effects of dihydrotestosterone, or DHT in some areas of the scalp. DHT is believed to shorten the growth, or anagen, phase of the hair cycle, from a usual duration of 3–6 years to just weeks or months. This occurs together with miniaturisation of the follicles, and progressively produces fewer and finer hairs. The production of DHT is regulated by an enzyme called 5-alpha reductase.
How common is male pattern hair loss?
Male pattern hair loss affects nearly all men at some point in their lives. It affects different populations at different rates, probably because of genetics. Up to half of male Caucasians will experience some degree of hair loss by age 50, and possibly as many as 80% by the age of 70 years, while other population groups such as Japanese and Chinese men are far less affected.
Female pattern hair loss
Female pattern hair loss (FPHL) is a distinctive form of hair loss that occurs in women with androgenetic alopecia. Many women are affected by FPHL. In fact, around 40% of women by age 50 show signs of hair loss and less than 45% of women actually reach the age of 80 with a full head of hair.
In FPHL, there is diffuse thinning of hair on the scalp due to increased hair shedding or a reduction in hair volume, or both. It is normal to lose up to 50-100 hairs a day. Another condition called chronic telogen effluvium also presents with increased hair shedding and is often confused with FPHL. It is important to differentiate between these conditions as management for both conditions differ.
FPHL presents quite differently from the more easily recognizable male pattern baldness, which usually begins with a receding frontal hairline that progresses to a bald patch on top of the head. It is very uncommon for women to bald following the male pattern unless there is excessive production of androgens in the body.
Platelet rich plasma therapy
Low fluence laser light therapy
The term alopecia means hair loss. In alopecia areata, one or more round bald patches appear suddenly, most often on the scalp. Alopecia areata is also called autoimmune alopecia.
Alopecia areata can affect males and females at any age. It starts in childhood in about 50%, and before the age of 40 years in 80%. Lifetime risk is 1–2% and is independent of ethnicity.
Causes of alopecia areata
Alopecia areata is classified as an autoimmune disorder. It is histologically characterised by T lymphocytes around the hair follicles. The onset or recurrence of hair loss is sometimes triggered by:
Clinical features of alopecia areata
Alopecia areata can affect any hair-bearing area, most often the scalp, eyebrows, eyelashes and beard.
Several topical treatments used for alopecia areata are reported to result in temporary improvement in some people. The hair falls out when they are stopped. These include:
Intralesional corticosteroid injections
Injections of triamcinolone acetonide 2.5–10 mg/ml into patchy scalp, beard or eyebrow alopecia areata may speed up regrowth of hair.
Oral and pulse intravenous steroids in high dose can lead to temporary regrowth of hair.
Telogen effluvium is the name for temporary hair loss due to shedding of resting or telogen hair after some shock to the system. New hair continues to grow.
Causes of telogen effluvium
In a normal healthy person's scalp about 85% of the hair follicles are actively growing hair (anagen hair) and 15% are resting hair (telogen hair). A hair follicle usually grows anagen hair for 4 years or so, then rests for about 4 months. The resting or telogen hair has a club or bulb at the tip. A new anagen hair begins to grow under the resting telogen hair and pushes it out.
If there is some shock to the system, as many as 70% of the anagen hairs can be precipitated into telogen, thus reversing the usual ratio. Typical precipitants include:
Chronic telogen effluvium
In some patients, hair shedding continues to be intermittently or continuously greater than normal for long periods of time, sometimes for years. The hair cycle appears to be reset so that the anagen period is shortened.
Chronic telogen effluvium often presents in women that actually continue to have quite thick and moderately long hair – this is because they notice the shed hair more than those with finer or shorter hair. Telogen effluvium does not cause complete baldness, although it may unmask a genetic tendency to genetic balding i.e. female pattern hair loss , or in men, male pattern hair loss.
Telogen effluvium is self-correcting. It is really not influenced by any treatment that can be given. However, gentle handling of the hair, avoiding over-vigorous combing, brushing and any type of scalp massage are important.
You should also ensure a nutritious diet, with plenty of protein, fruit and vegetables.
The doctor may check your thyroid function, and levels of iron, vitamin B12 and folic acid, as any deficiency in these can slow hair growth.