Synonym : Baldness, Hair loss.
- Alopecia is a condition where patchy, confluent or diffuse pattern hair loss occurs from different areas of the body, usually from the scalp.
- It is a very common problem in recent days. Alopecia, which is associated with progressive thinning of the scalp hair follows a definite pattern.
Incidence of Alopecia
- Incidence of alopecia is approximately 0.1–0.2% with a lifetime risk of men and women equally.
- High prevalence of mood change, depression and anxiety disorders are usually seen in patients with Alopecia.
Hair: anatomy and physiology
Hair is a non-living body structure composed primarily of a protein called keratin that is produced by organs within the skin called hair follicles.
- It has various functions such as protection against external factors; impact on social and sexual interactions; thermoregulation and being a resource for stem cells.
- Hair is a derivative of the epidermis and consists of two distinct parts: the follicle and the hair shaft.
b)Hair follicle: It is a sac like holes or the living part located under the skin or epidermis and dermis.
- A hair follicle anchors each hair into the skin.
- The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft.
- Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life.
Physiology of parts of hair:
- Hair shaft: portion visible above the skin. It protects against external factors; impact on social and sexual interactions.
- Dermal papilla: It contains tiny blood supply that nourish the cells at the base of the follicles.
- Bulb: Living part of the hair that surrounds the dermal papilla. Cells divide faster here than anywhere else in the body.
- Sebaceous gland: It produces sebum that conditions the hair and skin.
- Arrector pili muscles: It causes the hair to stand up and sebaceous gland to secrete sebum.
- Blood supply: Arteries and veins that supply nutrients to individual hair follicle.
Hair follicles grow in repeated cycles
One cycle can broken down into three phases:
— Anagen – Growth phase
— Catagen – Transitional phase
— Telogen – Resting phase
Each hair passes through the phases independent of the neighboring hair.
Anagen phase – growth phase
- Approximately 85-90% of all hair are in the growing phase at any one time.
- It can vary from two to six years.
- Hair grows approximately 10-15cm per year.
- Tip: Hair of any individual to grow more than one meter long.
Catagen phase–transitional phase
- At the end of the catagen phase.
- It lasts about one or two weeks.
- The hair follicle shrinks to about 1/6 of the normal length.
- The lower part is destroyed and the dermal papilla breaks away to rest below.
Telogen phase- resting phase
- It follows the catagen phase and normally lasts about 5-6 weeks.
- Approximately 10- 15% of all hair are in this phase at any one time.
- The hair does not grow but stays attached to the follicle.
- The dermal papilla stays in a resting phase below.
Formation of new hair
- At the end of the telogen phase the follicle re-enters the anagen phase.
- The dermal papilla and the base of the follicle join together again and a new hair begins to form.
- If the old hair has not already been shed the new hair pushes the old one out and the growth cycle starts all over again.
Causes of alopecia
Exposure to allergens, irritants, toxins, burns, injuries, and infections.
Certain medications (especially anabolic steroids like testosterone).
Chronic kidney failure.
Radiation and chemotherapy.
Types of alopecia
Androgenetic Alopecia (AGA)
Androgenetic Alopecia is often referred to as ‘Male Pattern Hair Loss’ or ‘Female Pattern Hair Loss’.
Mostly affects approx. 50% of men of 50 years and 50% of women of 65 years but can also affect younger men and women.
Causes: Hormonal- Dihydrotestosterone (DHT) factors in genetically susceptible individuals.
Action: Affects follicles causing hair to become small and complete shrinking of follicles eventually and stop hair growth.
Treatment : There is no cure for Androgenetic Alopecia but effects of Androgenetic Alopecia may be slowed down with treatments.
Scarring Alopecias : A rare group of disorders that destroy hair follicles. The hair follicles are replaced with scar tissue (cicatricial alopecia).
Occurs in men and women of all ages but it less common in children.
Symptoms : It can go unnoticed for long periods also. In other cases the hair loss is accompanied by burning, itching and pain and is more progressive.
Types : Frontal Fibrosing Alopecia, Lichen Planopilaris and Folliculitis Decalvans are more well known types of Scarring Alopecias.
Treatment : Treatments are available for the different kinds of Scarring Alopecias. An early diagnosis from a Dermatologist will provide the best chance of success.
Alopecia Areata (AA)
Alopecia Areata (AA) is an auto-immune condition. The immune system which normally protects the body from foreign invaders, such as viruses and bacteria, mistakenly attacks the hair follicles. This is what leads to hair loss.
The lifetime incidence of AA is approximately 2% worldwide.
Here are some key points about AA:
- Some patient show family history of AA.
- AA often develops suddenly, over the course of just a few days.
- People with mild patchy AA often experience a spontaneous, full recovery, without the need for treatment.
Types of alopecia areata
A.Alopecia Areata Patchy.
B.Alopecia Areata Totalis.
C.Alopecia Areata Universalis.
Patchy Alopecia Areata
Alopecia areata, the most common variation of the autoimmune disease, presents itself as round, smooth patches of various sizes.
Coin-sized patches of hair begin to fall out, mainly from the scalp. Any site of hair growth may be affected, though, including the beard called alopecia barbae and eyelashes.
Alopecia Areata Totalis.
Alopecia areata totalis is a type of alopecia areata presents itself as total loss of hair on the scalp.
It is an autoimmune disease.
It is more common in children and adults younger than 40 years.
Some people may also have a genetic predisposition for alopecia.
Stress – chronic stress weakens the immune system interfering the hair growth ability.
Alopecia Areata Universalis
Alopecia areata universalis is the rarest/advanced form of alopecia areata and presents itself as the loss of hair over the entire scalp and body.
Genetic and Environmental factors.
Complete loss of hair on both the scalp and body.
Most people with AU do not have other signs and symptoms, but some may experience a burning or itching sensation.
Anxiety, personality or paranoid disorders etc. are very common in people with different forms of alopecia areata.
Diagnosis : alopecia areata
Usually by looking at the extent of your hair loss and by examining a few hair samples under a microscope.
Scalp biopsy to rule out other conditions that cause hair loss like tinea capitis, etc.
Blood test depending on the particular disorder the doctor suspects.
Other blood tests that can help rule out other conditions include the following:
a)C-reactive protein and erythrocyte sedimentation rate.
c)free and total testosterone.
d)follicle stimulating and luteinizing hormone