To understand causes of hair loss, it is necessary to understand the science of hair.
Science of Hair Growth
Hair is made up of keratin, protein and has three parts including a shaft, a root and a follicle. Hair growth cycle consists of three phases.
Anagen- Growth phase
Almost 80-85% of hair in this phase refers to the lushly resting hair on the scalp. Each hair has an age of approximately 5 to 7 years and grows almost 10% per year.
Catagen- Transitional phase
After completing its growing period, hair enters into the catagen phase lasting one to two weeks. In this period, the follicle shrinks separating the skin outgrowth and causing the lower part of the hair to get destroyed.
Telogen- Resting phase
During this period hair doesn’t grow, but remains stalked to the follicle. About 15-20% of the hair is in the resting phase. This phase can be assumed as pause before shredding down lasting for 3 months. Normally, hairs are shed during the telogen phase of the hair follicle. Hairs are shed in this phase to allow the follicle to rest prior to initiating growth of a new hair and pushes old ones out if the scalp.
Types of hair fall:
Normal hair fall
Losing up to 100 strands of hair is perfectly normal. This is because those strands are replaced by new hair and is essential for normal healthy hair.
It is when shredding hair exceeds the number of naturally the growing ones, then it is not normal.
Causes of Hair Loss
Hair fall is a complex problem mediated by internal and external factors. It becomes naturally thinner with aging, but there are also many underlying causes. This loss can occur in many forms, including gradual thinning of hair, patchy spots, sudden loss of hair and more. Whatever the cause, there are solutions for every type of underlying issue, whether for temporary or permanent hair loss.
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Heredity can play a major role in both genders, when it comes to the pattern and extent of the hair loss. For men, the hair loss begins early and the hair line starts to recede partially or completely. As for women, the hair starts becoming thinner in the front, sides or top of the head.
Sometimes hair loss occurs by compulsive pulling of hair (trichotillomania). This is majorly found in young children where they pull out hair in response to anxiety. This can be encountered by counseling or cutting off the child’s hair short.
Hair loss after child birth
Childbirth often causes a temporary form of hair loss. During the second and third trimester of pregnancy, hair follicles on many women remain in the active growing phase. So, most pregnant woman have thicker and luxuriant hair.
Anyways, few months after childbirth, hair goes back to its regular growth cycle. All the follicles that would have been resting and shedding over the previous six months or so stop growing all at the same time, and a larger than usual amount of hair is shed. But this condition is temporary and hair grows back.
Women undergo massive hormonal changes at different points of their lives like the onset of menopause. Polycystic ovarian syndrome (PCOS) cause body produces too many androgens, the male hormones. They affect the degree and frequency of bleeding during menstrual cycle and can also cause acne and oily skin. If the hair follicles are sensitive to androgens they can also decrease the growth of hair on the scalp and increase the growth of hair on body.
Proper nutrients in food intake are needed to supply essentials for the growth of hair. Iron or vitamin B or protein deficiency can lead to hair loss.
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Lupus a chronic autoimmune disease in which the body’s own immune system attacks healthy tissues. Therefore the hair becomes brittle and fall out in patches above the forehead. Hypothyroidism (an under active thyroid gland) causes a little gland located in neck produces hormones. Hence, affects metabolism as well as growth and development leading to hair loss. Diabetes and high blood pressure are also known to contribute to hair loss.
The hair loss can also be a result from certain hair styles that pull tightly on the hairs, such as tight ponytails, braids and pigtails. Sometimes cosmetic products and procedures that weaken and damage the hair shaft can also result in hair loss.
For example, highly alkaline hair-relaxers and straighteners, as well as acidic permanent wave treatments, can cause hair loss. Straightening and permanent curling due to high alkalinity or acidity can cause hair loss. Hair grows after the use of products is discontinued.
Skin Conditions of the Scalp
An unhealthy scalp can cause inflammation that makes it difficult for hair to grow. Common skin conditions like dandruff, psoriasis, and fungal infections can lead to hair loss.
Dandruff causes the scalp to shed its skin encountered by yellowish scales on shoulders or on hair.
Psoriasis, an autoimmune condition that causes excessive skin cell turnover, produces a very thick white scale on the scalp that causes bleeding if it is pulled off.
With a fungus, red patches are found on scalp.
Hair loss from weight loss is generally due to a condition known as telogen effluvium. Physical, mental and emotional stress from losing weight can be a cause more hair than usual to go into resting phase than regular number. So, proper diet must be maintained while losing weight.
Some of the arthritis medications and blood thinners have side effects of hair loss. Chemotherapy and radiation therapy can cause hair loss, but the hair usually grows back after the treatment is over.
Stress can account to the cause of hair loss (Telogen effluvium). This condition is caused severe emotional or physiological incidents. Severe stress and emotions can cause currently growing hair to go into regression phase during which the hairs fall out easily.