What Triggers Hair Loss?

The Causes and Treatment of Alopecia

Sep 16, 2009 John Richard Roberts

Hair loss is caused by various factors which interfere with the hair growth cycle. Management of the condition relies on removing or counteracting these factors.

Although common, hair loss, also known as alopecia, can be highly distressing. Many men suffer from increasing baldness as they get older and they either adapt and get used to it or it causes them considerable discomfort even though they are in the company of around fifty percent of their fellows.

Baldness in the young or in women of any age nearly always gives rise to much anxiety. There are a number of reasons for hair loss and some of them result in temporary loss only.

Causes of Hair Loss

Hair loss often relates to hormonal state or general body condition. Some causes are poorly understood. The major reasons for the problem are outlined below.

Androgenic Hair Loss

Otherwise known as male pattern baldness, it is extremely common, affects women as well as men but in their case the scalp usually just thins rather than resulting in baldness. The problem is related to androgens, the receptors on the hair follicles seem to be more sensitive to androgens in those who go bald. In older women it occurs because there are fewer oestrogens circulating to counteract the androgens.

Alopecia Areata

The cause is unknown but it is thought to be an autoimmune response. Stress has been suggested as a factor. Hair loss is usually in patches. It can affect any age but young adults are most at risk. The condition usually affects the scalp but it can occur elsewhere.

If the condition is mild regrowth occurs within a few months but in more serious cases the baldness becomes permanent.

Physiological Stress

The condition is known as telogen effluvium and is the result of physiological stress which causes the hair to go into a dormant phase. Numerous triggers can precipitate the condition including:

• hormonal changes - pregnancy for example,
• poisoning.
• chronic illness.
• poor diet.
• skin disease.
• some types of medication.

The condition usually resolves when the underlying problem has been corrected.

Immuno-suppression

Anything which inhibits cell division can cause hair loss. Major causes are immunosuppressant drugs, chemotherapy and radiotherapy. Hair growth normally restarts when the therapy has finished.

Behavioural

Some emotional disorders can produce hair pulling which will cause traction alopecia.

Anatomy and Physiology of Hair

Each hair comes in two parts, the shaft – the bit that's seen and the root which is under the skin. The shaft is formed of three layers of modified epithelial cells - the cells which make the outer layer of the skin.

• The medulla: the inner most portion of the shaft.
• The cortex: this is the thickest of the three layers. It contains the pigment which gives hair its colour.
• The cuticle: the outermost layer made up of a layer of thin scale like cells.

The root contains the follicle from which hair growth takes place. Hair is constantly being shed and new growth occurs to replace that being lost. Hair grows at varying rates so, for example, some scalp hair will grow faster than others. Most of the follicles on the scalp are in the active phase so it's possible to lose up to a hundred hairs a day and not become bald.

Growth Cycle

Hair growth on the scalp happens in cycles. Most hair is in the growth phase, this lasts for three to five years and the hair grows around one centimetre per month. After this the hair goes into a dormant period when no growth takes place. This is followed by shedding of the hair and the start of new growth.

Treatment of Hair Loss

Treatment of the underlying cause is the prime approach – correct the hormonal problem or diet for example. Wigs are available and often used for those undergoing chemotherapy.

Counselling can be given for those who find the hair loss unsettling.

For androgenic hair loss the preparations monoxidil and finasteride are available. These can be successful but need to be used continuously or the hair growth stops.

They are generally more successful if used soon after the hair loss starts. In men with moderate hair loss minoxidil will produce 26% new growth in four months, in women the figure is 19% in that time.

This article is for information only. If you have any health concerns you should consult your doctor.

Resources

Human Physiology: The Basis of Medicine by Pockock and Richards Pub OUP 1999

Is Hair Loss Self-treatable? J J Pray. US Pharmacist 2003 28 (8)

The copyright of the article What Triggers Hair Loss? in General Medicine is owned by John Richard Roberts. Permission to republish What Triggers Hair Loss? in print or online must be granted by the author in writing.

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