Hair loss refers to a loss of hair from the scalp or body. The medical term for hair loss is alopecia. There are many different causes of alopecia, some permanent, others temporary. Hair loss is more common in men, affecting 60% of men and up to 40% of women.
Hair is composed of a protein called keratin. Hair grows everywhere on our skin, except for on our palms and the soles of our feet. The average adult head grows about 100,000 to 150,000 hairs, and 80 to 100 are normally shed each day. At any one point in time, around 90% of the hair on the scalp is growing. This is known as the anagen phase. There are three main phases of hair growth.
- The anagen phase. On average, hair grows approximately 0.3-0.4 mm a day on average or around 12-15cm per year, and this is genetically predetermined. As people age, their rate of hair growth slows. The hair root looks long, white, and tapered during this phase.
- The catagen phase. Hair growth stops during this phase and the hair root starts to shrink and become rounded. This phase may last from two to three weeks.
- The telogen phase. This is also called the resting stage. The hair root is now fully rounded, and awaiting the growth of a new anagen hair to push it out of the scalp so it can be shed. This phase lasts around three to four months for scalp hair, but can be as long as nine months for hair on other parts of the body, such as the eyebrows.
Types of Hair Loss
Hair loss can affect small areas of the scalp or occur evenly over the whole area. Depending on the cause, other hairy parts of the body may also be affected. The most common types of hair loss are:
- Male-pattern hair loss (baldness)
- Female-pattern hair loss
- Telogen effluvium (excessive shedding of telogen hairs)
- Anagen effluvium (excessive shedding of anagen hairs)
- Alopecia areata
- Other causes.
Male-Pattern Hair Loss
Male-pattern hair loss is an inherited condition and is also known as androgenetic alopecia. It is the most common type of permanent male baldness and affects male Caucasians more than other ethnicities. The condition is characterized by a receding hairline and/or hair loss on the top of the head.
Male-pattern hair loss is caused by an inherited increased sensitivity to dihydrotestosterone (DHT). DHT shortens the anagen phase of the hair cycle, causing progressively finer hairs to be produced. Men who do not produce testosterone (because of genetic abnormalities or castration) do not develop this pattern baldness. Male-Pattern hair loss affects about 20% of men in their 20s, 30% in their 30s and nearly half of men in their 40s.
Female-Pattern Hair Loss
Female-pattern hair loss is another inherited condition, although the pattern of hair loss is different from that of men. Female-pattern hair loss is characterized by a diffuse thinning of hair on the scalp or a widening of the center part, due to an increase in hair shedding. The frontal hairline usually remains intact.
The condition is more common near menopause affecting around 40% of women aged 50 and 55% of women aged 80.
This is a temporary thinning of hair over the scalp caused by the precipitation of a large number of anagen hairs into the telogen phase. At first, the hairs remain firmly attached to the scalp but within two months new anagen hairs push out the dead telogen hairs and increased hair shedding is noticed.
There are numerous causes of acute telogen effluvium including accidents, childbirth, certain medicines (for example, anticoagulants, antidepressants, the discontinuation of oral contraceptives), excessive weight loss or major dietary changes, illness, jet lag, and surgery. In most cases, complete recovery occurs in six to nine months.
Chronic telogen effluvium is characterized by an inability to grow hair long. Although it does not cause baldness there is a persistent or cyclical diffuse hair loss and bi-temporal recession of hair is common (causing a high forehead). Deficiencies in levels of thyroid hormones, iron, B12, and folic acid can also slow hair growth and these should be checked first.
This is the hair loss that occurs with chemotherapy medicines, although it can also occur as a result of exposure to toxins or due to inflammation. These effects disrupt actively growing hair cells and cause increased hair shedding, resulting in baldness, although hair usually grows back when treatment is finished. This type of hair loss also occurs with radiation therapy, but it is localized to the area of treatment, for example, if treatment is to the hip area only body hair in this area will be lost.
This is characterized by sudden bald patches appearing on the scalp, although any hairy area (such as the eyebrows, eyelashes, beard) can be affected. It is thought to be an autoimmune disease where the immune system attacks the hair follicles and commonly runs in families or affects people with chromosomal disorders, such as Down syndrome.
Complete regrowth may take months or years to occur. There are various forms of alopecia areata including alopecia totalis where all scalp hair is lost and alopecia universalis where the entire body hair is shed.
Tinea capitis is an infection of the scalp by a fungus, usually either Trichophyton and Microsporum fungi, that causes hair loss in the infected area. Treatment is with oral antifungals.
An over-active or under-active thyroid gland may cause hair loss that affects the whole scalp, making the hair appear uniformly sparse. Regrowth occurs on correction of the thyroid disorder although it may not be complete. Other conditions, such as diabetes or lupus can also cause hair loss.
Hair loss can also occur with excessive pulling or braiding of the hair; nervous habits or psychological conditions such as Trichotillomaniawhere the individual has strong urges to pull out their own hair, or with excessive shampooing or blow drying.
See your doctor if:
- You are losing hair in an atypical pattern.
- You are losing hair rapidly or at an early age (for example, in your teens or twenties).
- You have any pain or itching associated with hair loss.
- The skin on your scalp under the involved area is red, scaly, or otherwise abnormal.
- You have acne, facial hair, or menstrual irregularities.
- You are a woman and have male-pattern baldness.
- You have bald spots on your beard or eyebrows.
- You have been gaining weight or have muscle weakness, intolerance to cold temperatures, or fatigue.
Your doctor will take a detailed medical history and will examine the condition of your hair and scalp; this is usually enough to diagnose the nature of your hair loss. Your doctor will also ask questions such as:
- Are you losing hair only from your scalp or from other parts of your body as well?
- Is there a pattern to the hair loss like a receding hairline, thinning or bald areas on the crown, or is the hair loss throughout your head?
- Have you had a recent illness or high fever?
- Do you dye or blow dry your hair?
- Have you been under unusual stress lately?
- Do you have nervous habits that include hair pulling or scalp rubbing?
- Do you have any other symptoms like itching, flaking, or redness of your scalp?
- What medications do you take, including over the counter drugs?
Diagnostic tests that may be performed (but are rarely needed) include:
- Microscopic examination of a plucked hair
- Skin biopsy (if skin changes are present).
Treatment Options For Hair Loss
Not all cases of hair loss require treatment or can be treated. Temporary hair loss, such as acute telogen effluvium, especially that caused by childbirth or jet lag, is usually self-correcting and regrowth occurs within six to nine months.
For hair loss caused by cancer treatment, such as chemotherapy or radiotherapy, no treatment is necessary, although cooling caps (a specially designed ice pack or cap worn before, during, and after each chemotherapy) may be used as a preventive measure to protect the hair follicles. Hair will grow back a few months after the treatment has finished. Wigs, hats or other coverings may be worn during this time.
If a medication is causing your hair loss then your doctor may be able to prescribe a different medication to treat your condition if an alternative exists.
Male-Pattern Hair Loss
There are several treatments that may slow or prevent the development of male-pattern hair loss, although these must be used continuously, or the former pattern of hair loss will return.
Propecia (finasteride) is a prescription medicine that works by inhibiting the conversion of testosterone into 5 alpha-dihydrotestosterone (DHT), a hormone that plays an important role in hair loss in men.
Propecia can cause a decrease in sex drive and sexual function.
Male and Female-Pattern Hair Loss
Minoxidil can be helpful for male and female-pattern hair loss, or hair loss due to age and hormones. It works better in men or women who have a general thinning of the hair. Hair shedding may temporarily increase during the first few months of use and regrowth may take two to four months.
Continued treatment is required otherwise the pattern of balding reverts back to what it was before. The exact way that minoxidil works is not known. Other brand names of minoxidil may be available.
Rogaine (for Men and Women)
Good Sense Hair Regrowth Treatment, Rogaine Men's Extra Strength
Other medications that may be tried for hair loss but are not FDA approved for this indication include:
- Male-pattern hair loss: dutasteride
- Female-pattern hair loss: spironolactone, low-androgen oral contraceptives, hormone replacement therapy in postmenopausal women
- Alopecia areata: corticosteroids, cyclosporine (although the risks may outweigh the benefits).
Hair transplants are a surgical technique that removes hair follicles from one part of the head to another. It is mostly used to treat male-pattern baldness and the cost depends on how much hair is being moved but is usually around $4,000 to $15,000. Most people see 60% of new hair growth after 6 to 9 months.
Hair pieces, hair weaves or changes of hairstyle may disguise hair loss. This is generally the least expensive and safest approach to hair loss.