A normal hair goes through three phases, the anagen phase, the catagen phase and the telogen phase.
Hair loss, referred to as
A normal person loses around 100 hairs a day. But this hair loss usually goes unnoticed. Each hair undergoes three stages of development. Around 85 to 90% hairs on the head are usually in the anagen or growing stage. They remain in this stage for 2 to 6 years. This is followed by the catagen or involution phase that affects 2 to 3%of hair follicles. This is followed by the telogen or resting phase in which 10 to 15% of hair follicles undergo a period of rest for around 3 months. Following this stage, the hair is ejected from the skin leaving a solid, hard nodule.
A careful examination of the areas of hair loss on the scalp helps in the diagnosis of the underlying condition. The hair pull test is one of the tests used to diagnose hair loss. When a gentle traction is applied from the base to the tips of a group of 25 to 50 hairs, in a normal person only 1 or 2 hairs get dislodged. However, in conditions of excess hair shedding, 10 to 15 hairs can get dislodged. The hair is then carefully studied and subjected to microscopic examination. Blood tests may be ordered depending on the suspected underlying condition. In some cases, a scalp biopsy may be required.
What Causes Hair Loss
The cause of hair loss may vary from a local condition affecting the scalp to an ailment affecting the whole body.
The common causes of hair loss are listed below:
Androgenetic Alopecia: Androgenetic alopecia is the male-pattern baldness that runs in families. The hair is lost in an M-shaped pattern, with loss at the crown and temples and sparing of the sides and back of the head. Such alopecia may also be seen in women with loss of hair in the front and central part of the head. Women with this type of baldness may show excess androgen levels and should be evaluated for other conditions like hirsutism, polycystic ovarian syndrome, acne and infertility.
Telogen Effluvium: Telogen effluvium is a condition where the normal balance between the resting and growth phases of hair is disrupted, resulting in a predominant telogen phase. Thus, it leads to excessive shedding of hair and a decrease in the total number of hair. Some of the conditions that can result in telogen effluvium are:
- Physiological stress like surgery, severe illness, emotional crisis or pregnancy.
- Medical condition: Medical conditions that can cause hair loss include:
- Hypothyroidism and hyperthyroidism
- Systemic amyloidosis
- Liver or kidney failure
- Inflammatory bowel disease
- Lymphoproliferative disorders
- Autoimmune diseases like systemic lupus erythematosus and dermatomyositis
- Chronic infections like HIV and secondary syphilis
- Inflammatory disorders like psoriasis, seborrheic dermatitis and allergic contact dermatitis
- Nutritional factors: Nutritional factors that can cause hair loss include:
- Zinc deficiency
- Iron deficiency
- Severe decrease in protein, fatty acid and calorie intake due to starvation or dieting
- Malabsorption syndromes and pancreatic disease
- Vitamin D deficiency
- Medications: Medications that can cause telogen effluvium are oral contraceptives, androgens, retinoids, beta-blockers, angiotensin-converting enzyme inhibitors, anticonvulsants, antidepressants, and anticoagulants.
The event may have occurred up to 3 months before the hair loss incident. Treatment of the underlying condition usually results in resolution of the hair loss. Thus, telogen effluvium is a sign of an underlying condition and not a disease by itself.
Alopecia Areata: Alopecia areata is a condition where the patient suffers from a localized hair loss. When the hair loss extends to the whole scalp, the condition is called alopecia totalis. If it is accompanied by hair loss over the entire body, it is called alopecia universalis. The hairs over the affected area resemble exclamation points, that is, the hair is thinned out but the caliber of the hair at the base remains the same. It may be associated with autoimmune conditions. Most patients recover without treatment in 6 to 12 months. Recurrence occurs in 30% cases. Prognosis is worse if the condition lasts for more than a year, if it worsens, begins before puberty, is present in other members of the family or in patients of Down’s syndrome.
Anagen Effluvium: Loss of hair in the anagen phase occurs due to chemotherapy, radiotherapy (radiotherapy can also cause telogen effluvium), heavy metal poisoning and boric acid poisoning.
Trichotillomania: Trichotillomania is a psychiatric condition where the patient plucks out his or her own hair. It may develop between 8 to 12 years of age. The hair loss appears bizarre, with incomplete areas of clearing. In some cases, the patient may also eat up the plucked hair resulting in obstruction in the intestines.
Traction alopecia: Traction alopecia is a condition where the person suffers from hair loss due to tight tying of hair in ponytails or plaits. A change in hair style is necessary to prevent further hair loss in these patients.
Tinea capitis: Tinea capitis is ringworm infection of the scalp. It is a type of fungal infection where there may be a boggy lesion on the scalp over which the hair are increasingly fragile and breaks easily.
Cicatricial alopecia: Cicatricial alopecia is a condition where the hair follicles are permanently destroyed, resulting in permanent hair loss. It could be caused by a number of conditions like inflammation, autoimmune conditions like discoid lupus and infections like cellulitis.
Frequently Asked Questions
1. Which doctor should I visit in case I suffer from hair loss?
You should visit a skin specialist (a dermatologist) or a trichologist in case you suffer from hair loss.
2. What are the common reasons for diffuse hair loss?
Diffuse hair loss over the scalp as well as the rest of the body occurs due to alopecia universalis. Hair loss only over the scalp with majority of the hair in telogen phase is due to telogen effluvium. Hair loss over the scalp with exclamation-point hair indicates alopecia totalis.
3. What are the common reasons for focal hair loss?
Focal hair loss with patchy, exclamation-point hairs indicates alopecia areata. Tinea capitis causes hair loss with scalp bogginess and fragile or easily broken hairs. Patchy, incomplete thinning, with stubble may indicate trichotillomania. Loss of hair in the front and sides of the scalp with high-tension hairstyle indicates traction alopecia. The presence of infection like cellulitis and folliculitis indicates cicatricial alopecia.
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