Hairfall

The five phases of the Hair Cycle are as below 

1. Anagen (Growing phase)
90-95% hair is present in this constantly growing stage which may last from 2-7 years.

2. Catagen
Less than 1% of the total hair population is in regressing phase which lasts for 2-3 weeks.

3. Telogen (Resting phase)
This usually occurs in the end where 5-10% of total hair follicles are in this stage at any given time. This phase lasts for 3 months.

4. Exogen (Shedding phase)
After the Telogen phase gets completed, hair follicles are bound to shed off.

5. Kenogen (Lag phase)
The duration between which the hair bulb lies empty or devoid of any hair shaft and the growth of new hair, the follicle lies in the lag phase.

Hair cycle is under influence of hormones, neural response and molecular control of the body.

Hormones influencing Hair Growth

Androgens, estrogens, prolactin all are said to increase the duration of anagen, and the size of the hair follicle, which in turn increases the thickness of the hair shaft. Insulin, IGF, cortisol, and catecholamines promote follicular growth.

Thyroid hormones- Hyper or hyposecretion may retard the rate of hair growth and prolong the retention of club hair.
Out of all these, Androgens are the most important hormone affecting hair growth.

Neural control of hair growth- Exposure to psychoemotional stress and release of mediators of the general stress response (CRH, b-endorphin, prolactin, catecholamines) can also influence the physiologic hair growth pattern.

Molecular control of hair growth- FGF-7, Shh, PTHrp, Wnh, BDNF, TGF-b, ACTH, NT-3, NT-4 are some of the molecules responsible for hair regeneration.

Normal Growth of Hair

• Scalp hair grows 0.45mm/day.
• Beard hair grows 0.35mm/day.
• Extremities hair grows 0.25mm/day.
• Vellous hair on the forehead grows 0.03mm/day.

Classification of Hair Loss

1. Non Scarring hair loss is when follicles are visible and normal skin markings are present- Alopecia Areata, Androgen Alopecia, Telogen Effluvium, Trcihotillomania, Tinea Capitis, Traction Alopecia. 

2. Scarring hair loss is when follicles are not visible and smooth shiny atrophic skin may be seen -Chronic Discoid Lupus Erythematosus, Lichen Planus, Lichen Scelorosus, Morphea (localised scleroderma). Others include cancers/trauma/Infection.Hair loss (Hairfall) can be due to primary pathology at the level of hair follicles.

Hair loss due to primary pathology in hair shaft

• Pili torti.
• Monilethrix.
• Monilethrix.
• Trichorrhexis nodosa.
• Trichothiodystrophy Pili annulati.
• Woolly hair.
• Uncombable hair.
• Loose anagen hair.
• Trichostasis spinulosa.
• Pili multigemini.
• Weathering of the hair shaft.

What Causes Hair Loss?
There are many types of hair loss (Hairfall) but these are the most common cases seen at our clinic. 

1. Androgenetic Alopecia (Male-pattern and female-pattern hair loss)
This is the most common type of hair loss (Hairfall) affecting 58% of middle aged males in Indian population. Most of the men observe thinning of hair mainly on the temples and the crown whereas women observe thinning of hair mainly at the frontal area of the scalp. There are many types of hair loss, also called alopecia, but these are the most common that we see at our clinic.

2. Telogen Effluvium
An individual, on an average sheds 50-100 hair, daily. Many hair follicles enter the phase of the telogen at the very same time. When this happens, increased and sometimes dramatic hair shedding, known as telogen effluvium occurs, in which the hairfall starts, shedding, and becomes thin. The condition is typically frightening and can appear unexpectedly, creating significant thinning, although it does not result in complete baldness and often recovers entirely, especially once any underlying problem is corrected.

3. Hair shedding is often caused by factors such as 

• Pregnancy and childbirth.
• Medication (such as Roaccutane which is taken for acne).
• Low iron level (this is common in vegetarians).
• Sudden weight loss.
• Significant illness (e.g. glandular fever).
• Stopping oral contraceptive pills.
• Thyroid problems.

4. Alopecia Areata
This is a condition which causes patchy loss of hair, leaving areas of complete baldness. It can affect only 1 in 50 people where the immune system attacks the hair follicles. There are possibilities that about 1 in 5 people will not recover and this is more likely a hair loss if total or near-total (alopecia totalis /universalis), or if the hairline at the front, sides or back gets affected. 

5. Centrifugal Cicatricial Alopecia
People who often use hot combing, braiding, chemical relaxants or tight extensions may observe hair loss at the top of the scalp, a condition dermatologists name as centrifugal cicatricial alopecia. It is also a condition which should get recognized early as it might become permanent and severe if not treated. Tying hair back tightly or using braids can also cause traction alopecia, a condition which is reversible but which can become permanent if the follicles are badly damaged.

6. Frontal Fibrosing Alopecia
Women who have experienced menopause are the one’s who develop a receding frontal hairline, different from female-pattern hair loss with permanent scarring of the follicles. This has been recently recognized and is called as frontal fibrosing alopecia. It can be treated using topical steroid lotions and tablets that switch off the inflammation in the skin that causes the problem. Early diagnosis is the key.

7. Post COVID hair loss
With COVID, comes this new problem of hair loss (Hairfall). It is a type of late telogen effluvium, where one notices excessive hair loss within weeks to months after fully being recovered from the infection. It occurs as a late reaction to a physical stress like infections or mental stress. It can go on till 3-4 months, but is reversible. Many patients bring complaints of their hair coming out in large clumps, thinning along the hairline and loss of hair volume or pronounced thinning. After infections such as COVID, malaria, dengue, typhoid etc., there is increased inflammation in the body, which leads to increase in cortisol levels. This cortisol hormone can cause normal hair to go into shedding phase. Fever, anxiety and stress can all lead to increased inflammation and diffuse hair fall. Prolonged infections can lead to deficiency of nutrients in the body which in turn can result in weak and brittle hair. 

All these factors result in early shift of hair in the growing phase to the shedding phase. Though it is quite distressing for the patients, there is nothing that a timely intervention and consultation with a dermatologist won’t fix.