The condition may begin at any age. Hair loss often begins on the front, sides, or on the crown of the head. Some men may develop a bald spot or just a receding hairline. Others may lose all of their hair. Alopecia areata. This hair loss disorder is characterized by sudden loss of hair in one particular area. The hair grows back after several months. However, if all body hair is suddenly lost, regrowth may not happen.
The exact cause of this type of hair loss is unknown. There is a genetic link as well as a link with autoimmune conditions and allergies. If hair loss is complete on the scalp, it is called alopecia totalis, and if all body hair is lost, it is called alopecia universalis.
Toxic alopecia. Toxic alopecia may happen after a high fever or severe illness. Certain medicines, especially thallium, high doses of vitamin A, retinoids, and cancer medicines may also cause it. Medical conditions, such as thyroid disease, and giving birth may also trigger toxic alopecia. The condition is characterized by temporary hair loss. Scarring or cicatricial alopecia. Scarred areas may prevent the hair from growing back. Scarring may happen from burns, injury, or X-ray therapy.
However, other types of scarring that may cause hair loss can be caused by diseases. These include lupus, bacterial or fungal skin infections, lichen planus, sarcoidosis, tuberculosis, or skin cancer. This is one of the most commonly reported types of hair loss, referring to bald patches or spots on the scalp.
This is hair loss affecting the whole of the head, including eyelashes and eyebrows. It is a more advanced stage of alopecia areata, which progresses to totalis and universalis in around 1 — 2 per cent of cases. In chronic cases, scarring alopecia may result.
Cicatricial or scarring alopecia causes permanent hair loss from destruction of the hair follicles by inflammatory or autoimmune diseases. The most common cause of this is discoid lupus erythematosus, which produces atrophied erythematous patches, sometimes with telangiectasia. Telogen effluvium occurs when an increased number of hairs enter the telogen resting phase of the hair cycle from the anagen growing phase, and these hairs are lost approximately three months later.
Usually, an average of hairs are lost each day, but this becomes significantly more in telogen effluvium, in which 30 to 50 percent of body hair can be lost. Telogen effluvium may be precipitated by severe illness, injury, infection, surgery, crash diets, psychological stress, giving birth, thyroid disorders, iron deficiency, anemia, or drugs.
Hyperthyroidism and hypothyroidism can cause telogen effluvium, which is usually reversible when the thyroid status is corrected except in long-standing hypothyroidism.
Severe iron deficiency anemia may be associated with it, but this remains controversial. No cause is found in approximately one third of cases. Patients with telogen effluvium usually present with an increased number of hairs in their hairbrush or shower, and sometimes thinning of the hair in the scalp, axillary, and pubic areas. A detailed history may indicate the cause of the hair loss, which usually has occurred two or three months before the hair falls out.
On examination, there is generalized hair loss with a positive hair pull test, indicating active hair shedding, particularly at the vertex and scalp margin. The hair pull test is done by grasping approximately 40 to 60 hairs between the thumb and fore-finger and applying steady traction slightly stretching the scalp as you slide your fingers along the length of the hair.
Generally, only a few hairs in the telogen phase can be plucked in this fashion. Less than 10 percent is considered normal, whereas greater than this is considered indicative of a pathologic process. Anagen effluvium is the abrupt loss of 80 to 90 percent of body hair, which occurs when the anagen growing phase is interrupted. The main cause of this is chemotherapy. Up to 50 percent of women will experience female pattern hair loss during their lifetime.
Women who also have abnormal menses, history of infertility, hirsutism, unresponsive cystic acne, virilization, or galactorrhea should have a targeted endocrine work-up for hyperandrogenism i. A hyperandrogenic state may limit the success of treatment with minoxidil, 30 and, in these women, spironolactone Aldactone to mg daily may slow the rate of hair loss. Male pattern hair loss sometimes referred to as male androgenetic alopecia affects up to 50 percent of all white men by 50 years of age.
Dihydrotestosterone DHT , the androgen derived from testosterone, plays a key role in male pattern hair loss, and men with lower levels of DHT have less hair loss.
Treatment with finasteride can cause decreased libido, impotence, and ejaculation disorders. Its mechanism of action is unclear.
Some shedding during the first few months of treatment is common. Several small studies have shown some increased effectiveness with combined minoxidil and finasteride treatment. Discontinuation of finasteride or minoxidil results in loss of any positive effects on hair growth within 12 and six months, respectively. Begin by determining if hair loss is focal or diffuse; if focal, look for scarring. Patients with scarring should be referred to a dermatologist.
In nonscarring focal alopecia, alopecia areata or tinea capitis are most common. In alopecia areata, the lesion is round and smooth, whereas in tinea capitis, the skin can look slightly scaly and erythematous, and there may be occipital adenopathy. A scraping of the lesion to evaluate for fungi may help. Traction alopecia and trichotillomania tend to cause more patchy hair loss and can usually be determined from the history.
Consider a scalp biopsy if the diagnosis of the focal hair loss is not clear. In diffuse hair loss, ask if the loss is predominantly hair thinning or shedding, if there is a relationship to any inciting event, and if there are symptoms of anemia, hyperandrogenism, or thyroid disease. The patient who presents with gradual hair thinning most likely has male or female pattern hair loss recognized by the typical patterns. The hair pull test will be positive where the hair is thinning, but negative away from the thinning areas.
Patients with hair shedding may have telogen effluvium or diffuse alopecia areata, both of which cause a positive hair pull test. The history may reveal the precipitating event in telogen effluvium, whereas patients with alopecia areata may have exclamation point hairs.
In all patients with diffuse hair loss, serum ferritin and thyroid function tests should be ordered. Patients with suspected telogen effluvium can be observed until spontaneous resolution occurs, usually within six months, provided the provoking stimulus has been removed.
If hair loss does not resolve, a scalp biopsy to differentiate between alopecia areata, telogen effluvium, and male or female pattern hair loss should be obtained. Already a member or subscriber?
Log in. Interested in AAFP membership? Learn more. SEAN W. Address correspondence to Anne L. Reprints are not available from the authors. Price VH. Treatment of hair loss. N Engl J Med. Incidence of alopecia areata in Olmsted County, Minnesota, through Mayo Clin Proc. Profile of alopecia areata: a questionnaire analysis of patient and family. Int J Dermatol. The pathogenesis of alopecia areata.
Dermatol Clin. Interventions for alopecia areata. Cochrane Database Syst Rev. Guidelines for the management of alopecia areata.
Br J Dermatol. The pattern of hair loss in women differs from male-pattern baldness. In women, the hair becomes thinner all over the head, and the hairline does not recede. Androgenetic alopecia in women rarely leads to total baldness. Androgenetic alopecia in men has been associated with several other medical conditions including coronary heart disease and enlargement of the prostate.
Additionally, prostate cancer , disorders of insulin resistance such as diabetes and obesity , and high blood pressure hypertension have been related to androgenetic alopecia. In women, this form of hair loss is associated with an increased risk of polycystic ovary syndrome PCOS. PCOS is characterized by a hormonal imbalance that can lead to irregular menstruation, acne, excess hair elsewhere on the body hirsutism , and weight gain. Androgenetic alopecia is a frequent cause of hair loss in both men and women.
This form of hair loss affects an estimated 50 million men and 30 million women in the United States. Androgenetic alopecia can start as early as a person's teens and risk increases with age; more than 50 percent of men over age 50 have some degree of hair loss. In women, hair loss is most likely after menopause.
A variety of genetic and environmental factors likely play a role in causing androgenetic alopecia. Although researchers are studying risk factors that may contribute to this condition, most of these factors remain unknown. Researchers have determined that this form of hair loss is related to hormones called androgens, particularly an androgen called dihydrotestosterone. Androgens are important for normal male sexual development before birth and during puberty. Androgens also have other important functions in both males and females, such as regulating hair growth and sex drive.
Hair growth begins under the skin in structures called follicles.
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