What causes your hair to fall ?
Hair Growth Cycle
Hair follicles exhibit intermittent activity, with each hair growing to a maximum length, being retained for a period of time without further growth, and eventually getting shed off and replaced. The hair cylinder arises from the division of cells in the region called hair bulb or hair root. The cuticle or the outer layer of hair is covered by hair keratin, a sulphur rich protein that protects the hair strand from premature breakdown due to physical and chemical insults. Human hair grows in 3 phases with Anagen or active growth phase of scalp hair lasting as long as 3 years, followed by a relatively short transitional phase Catagen, occupying about 2 weeks in the human scalp, and a resting phase or Telogen. Towards the end of the active growth phase, the scalp follicles show a gradual thinning and lightening of pigment at the base of the hair shaft, the base of the hair becomes club-shaped and is gradually shed off during the resting phase.
There are around 5 million hair follicles in an adult, of which about 1 million are on the head and 1,00,000 in the scalp.
The hair density decreases with advancing age. In adults aged 20-30 years, there is 615 hair per cm2; between 30-50 years the mean density is 485/cm2; and by 80-90 years it remains 435/cm2.
In an adult human scalp, hair growth occurs in a mosaic pattern, that is, the activity of each hair follicle is independent of its neighbours.
On an average, around 100 adult scalp hair are shed off every day.
The ends of the hair are oldest and bear the maximum stress. So the cuticle or the protective shield of the shaft gets ripped off, and you suffer from split ends medically termed as trichoptilosis.
Androgenetic Alopecia or Common Baldness
Alopecia or hair loss can occur due to various reasons, the most common being male pattern baldness. It is a physiological process in genetically predisposed individuals that leads to progressive transformation of coarse terminal hair follicles of scalp into fine soft vellus follicles, that is, a miniaturization process occurs, causing a gradual reduction in hair density. It occurs in both men and women post-puberty and has some genetic influence of multifactorial origin. Women usually present as a diffuse frontovertical hair loss apparent at 25-30 years of age and often associated with the Polycystic ovarian disease. They also suffer from acne, hirsutism (unwanted hair growth on the face, chest and upper back ) and greasiness of skin, along with hair fall. Men with baldness show a bitemporal recession of hair followed by balding of the vertex. They have elevated serum levels of hormone dehydroepiandrosterone sulphate (DHEAS).
On skin and hair follicles, the enzyme 5 alpha reductase leads to conversion of the male hormone testosterone to a more active metabolite dihydrotestosterone (DHT) that leads to miniaturization of hair follicles and recession of hairline. In susceptible individuals, as the exposure to DHT begins at puberty, a "genetic clock" is set running, which leads to the follicles to undergo cycles of decreasing length, producing finer and finer hair, until typical balding is apparent.
Disturbances in hair cycle: Telogen effluvium
In a normal young adult, scalp 80-90% of hair follicles are in the anagen or active growth phase. In telogen effluvium, certain severe stress leads to premature precipitation of anagen hair into telogen or resting phase, and then getting shed off. Fever, prolonged and difficult childbirth, surgical operations, haemorrhage and blood donation, crash dieting, emotional stress and prolonged jet flights may all induce this response. More than 100 to 1000 hair may be lost daily on combing or during shampooing.
Classification of hair fall
Non cicatricial alopecia
malnutrition assoc hairfall
- Human hair grows in 3 phases- anagen, catagen and telogen.
- On an average, around 100 adult scalp hair are normally shed off every day.
- Common baldness is associated with progressive hair fall in genetically predisposed individuals.
- Chronic severe stress leads to hair fall.
- Thyroid disorders, diabetes mellitus, PCOD, anticancer medicines cause hair loss.
- Malnutrition, protein, iron and essential fatty acid deficiencies lead to thinning of hair.
- Tight braiding, overenthusiastic hair massage and vigorous combing, causes hair damage.
Diffuse alopecia of endocrine origin
If pituitary gland of the brain is inactive since birth, the person is a hairless dwarf. If it gets damaged after puberty, as in Sheehan's syndrome (post delivery pituitary damage due to excessive blood loss ), then the scalp hair become very thin.
Diffuse loss of scalp hair, the sparsity of eyebrows and decrease in the hair on the underarms is evident.
A hyperactive thyroid is also associated with mild hair loss.
In this, the scalp hair is coarse, sparse, dry, easily shed with slight trauma and hair loss is patchy.
Poorly controlled diabetes leads to hair fall.
Post delivery hair loss 4-6 months after childbirth occurs due to hormonally mediated changes in cycles of scalp hair follicles.
Oral contraceptive intake
Hairfall due to chemicals and dietary factors
Many medicines in therapeutic use lead to hair fall. These include thallium, thyroid antagonists-thiouracil, anticoagulants-heparin, anticancer medicines, antipsychotics, boric acid, propranolol and metoprolol.
Malnutrition and protein deficiency lead to hair fall. The hair becomes brittle, lusterless, with a reddish tinge and get easily shed off. Hair fall in teenagers with Anorexia nervosa, purposeful low-calorie intake with a diet high in vegetables containing vitamin-A, is a psychogenic condition. Iron deficiency, even in the absence of anaemia, causes hair fall. Zinc and essential fatty acid deficiency lead to hair becoming dry, unruly and fragile.
Hairfall associated with disease states
Impaired liver function from hepatitis or cirrhosis leads to disturbances in amino acid metabolism causing hair loss.
Severe long-term illnesses like cancer cause hair fall due to associated anaemia and cachexia.
Alopecia may occur after encephalitis, head injury and diseases like myotonic dystrophy.
In this condition circumscribed, totally bald, smooth, circular patches occur on the scalp, often noticed by a parent, hairdresser or a friend. Herein, a wave of hair follicles enters the resting phase prematurely, leading to hair fall. Genetic factors, atopy, autoimmune reactions and severe emotional stress lead to this problem.
Hair loss resulting from deliberate, although at times unconscious efforts of a person who is under tension or psychologically disturbed.
Tight braiding, brush rollers being applied vigorously, use of hot combs, overenthusiastic head massage and hair weaving lead to hair fall.
Hair loss resulting from trauma.
Hair loss that accompanies or follows the destruction of hair follicles, whether by a disease affecting the follicles themselves or by some process external to them. Alopecia is irreversible, and may be caused by trauma, burns, fungal infections, furuncles, viral infections, tumors affecting the scalp, skin diseases like lichen planus, lupus and sarcoidosis.