While hardly life-threatening, going bald can be a blow to a patient’s self-image — or an important sign of underlying systemic disease.

Alopecia areata is marked by coin-shaped areas of nonscarring hair loss.

When patients complain that they are going bald, what advice can the primary-care physician offer? In some cases, hair loss may be a matter of heredity and the passage of time. Children have more hair than adults, and the average person in his or her early 20s has about 100,000 scalp hairs. Generally, redheads have the largest number of hairs, and dark-haired individuals have the fewest. As we age, however, alopecia becomes extremely common. Fifty percent of men and 10%-15% of premenopausal women show evidence of hair loss. As many as 75% of women older than 65 years of age have hair loss. In some patients, such loss can be a sign of underlying disease, and treatment of the disease may halt or reverse the loss. For others, hair loss may be the result of lifesaving therapy, a minor side effect on the way to an all-important goal. This article looks at hair loss and what, if anything, can be done about it.

Susceptible populations

Hair loss occurs most commonly in Caucasians and Hispanics, with African Americans and Asians close behind. Native Americans and Eskimos have the lowest incidence.

Androgenetic alopecia is caused by shrinkage of the hair follicle and is related both to the patient’s age and genetics. Men who have androgenetic alopecia experience two kinds of marked hair loss — male pattern baldness, a horseshoe pattern of hair around the sides of the head, and temporal hair loss, in which gradual bitemporal thinning results in recession of the anterior hair line in an M-shaped pattern (Figure 1).

Figure 1. In men, gradual thinning of temporal hair results in an M-shaped receding hairline.

In female pattern loss (Figure 2), the entire scalp area demonstrates increased shedding of telogen hair. Bitemporal hair loss is usually subtler than in men. Most women maintain their frontal hairline. The majority of women with androgenetic alopecia have normal endocrine function, including gender-appropriate levels of circulating androgens, and hormonal evaluation is unnecessary. A woman may not notice the hair loss per se. Instead she may notice that her ponytail or braid is getting thinner. Because women style their hair more than men do, hair loss in women can be more effectively disguised.

Figure 2. Female pattern baldness is marked by diffuse hair loss over the entire scalp.

Other causes of hair loss

Hair loss can be caused by systemic disease, autoimmunity, medications, and trauma. Identifying characteristics of the various forms of hair loss and their treatment are presented in Table 1.

• Systemic disease:

Several systemic diseases can cause hair loss. These include malnutrition, iron deficiency, endocrine and metabolic disorders, collagen vascular diseases, and such infections as syphilis. Patients with secondary syphilis sometimes develop a nonscarring alopecia that takes on a random pattern called “moth-eaten” alopecia. This condition will improve with treatment of the syphilis. Alopecia-related fungal infections are common in children. Suspected infection should always be treated. Most hair loss, however, is not associated with any underlying disease.

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• Immune-mediated loss:

Alopecia areata is an autoimmune reaction that usually manifests as coin-shaped areas of nonscarring hair loss on the scalp, eyebrows, and beard. The areas of loss are typically 1-5 cm in diameter. Early in the disease, the hair may turn gray; returning hair may be gray or white at the outset. Other systemic manifestations of alopecia areata include fingernail pitting that is regular and shallow and has been compared with pounded brass. Individual hairs often have frayed distal ends and an attenuated bulb similar to the “exclamation-point” hairs seen in trichotillomania.

Treatment is usually intralesional triamcinolone 2-5 mg/mL. Each area receives 0.1 mL, with a maximum dosage of 2 mL per visit. Topical immunotherapy (i.e., with contact sensitizers, such as dithranol and 2,4-dichloronitrobenzene) is also effective. Additional agents have been used, including minoxidil, psoralen plus UVA, and anthralin, with variable effect.

Alopecia areata resolves spontaneously within 6-12 months. Prognosis is worse when the disorder persists for longer than one year, worsens, or begins before puberty. Persons with a family history or commonly associated disorders, such as atopy, Down syndrome, autoimmune disease, or ophiasis also have a poorer prognosis. Recurrence occurs in 30% of patients and usually affects the initial area of involvement.

• Medications:

Medications cause hair loss by (1) inducing an abrupt cessation of mitotic activity in rapidly dividing hair matrix cells (anagen effluvium) or (2) precipitating premature follicular rest (telogen effluvium).  Anagen effluvium is typically due to chemotherapeutic medications. The most severe hair loss occurs with doxorubicin, the nitrosoureas, and cyclophosphamide. Hair loss usually begins 7-14 days after a single pulse of chemotherapy and is most pronounced after one to two months. Other medications that can cause hair loss are bismuth, levodopa, colchicine, and cyclosporine. Exposure to such chemical agents as thallium, boron, and arsenic can also precipitate anagen effluvium.

Telogen effluvium is caused by antimalarials, beta blockers, sex hormones, ACE inhibitors, angiotensin II antagonists, anticoagulants, retinols (vitamin A, etretinate, isotretinoin), interferons, and antihyperlipidemic drugs.

• Mechanical causes:

Chemicals and trauma can cause hair loss. Traction alopecia occurs most commonly in African Americans who wear tight braids (especially “cornrows”) that lead to high tension and breakage in the outermost hairs. The hair thinning is first noted in the frontal and temporal areas but depends on the hairstyle. Traction alopecia can also occur in patients who use a hot comb to straighten kinky hair and when the hair is frequently pulled back. Treatment consists of halting the causative practice and applying minoxidil. Sometimes, if the process is long-standing, nothing will facilitate hair growth.

Pharmacologic treatment modalities

Minoxidil and finasteride are the two main treatments for alopecia. Many products or procedures are touted to treat alopecia — vitamins, “natural” hormone inhibitors, trace elements, exotic herbs, amino acids, laser therapy, and scalp massage — but none has supporting data.

• Minoxidil:

This OTC agent can slow central and vertex hair loss in men and women. Applied twice daily, minoxidil can take at least four months to have an effect and achieves its peak effect at about six months. One year of use is optimal for assessing efficacy. Discontinuation results in a rapid reversion to the pretreatment state.  Minoxidil is available in two strengths: 2% and 5%. The latter formulation is marketed only for men. Minoxidil, particularly the 5% strength, can increase facial hair in women. The efficacy of the 2% solution may be increased, however, by the synergistic use of once-daily tretinoin applied at separate times during the day. Preparations of minoxidil as strong as 13% are available on the Internet, but their relative effect has not been determined. The monthly cost of a 2% solution applied in a daily dosage of 2 mL/day is about $30-$40.

Minoxidil’s mode of action is unknown. It appears to lengthen the anagen phase and may increase the blood supply to the follicle. It is most effective for recent-onset androgenetic alopecia, small areas of hair loss, male pattern baldness, and female pattern hair loss. Particularly in men, minoxidil may work better in areas with higher concentrations of miniaturized hairs. It does not work on completely bald areas.

• Finasteride:

While hair loss is not preventable, it can be slowed by finasteride 1 mg/day, available for men only by prescription. Finasteride decreases androgenetic alopecia and stimulates hair growth in many patients. Although it primarily ameliorates vertex balding, finasteride has been shown on rare occasions to increase regrowth in the frontal area as well. Women who might be pregnant should not handle finasteride because it may cause ambiguous genitalia in a developing male fetus.

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One of finasteride’s relatively few side effects is loss of libido in 1%-5% of men, but this usually resolves if the medication is discontinued. Breast tenderness and enlargement, decreased amount of semen per ejaculation, impotence, itching, rash, swelling, thyroid disorder, and testicular pain are also rare side effects. Men who take finasteride have lower prostate-specific antigen (PSA) levels and should inform the physician who checks their PSA. The monthly cost of finasteride (1 mg/day) is about $50-$70.

Finasteride is a 5α-reductase type 2 inhibitor, not an antiandrogen. Taken orally, it inhibits the conversion of testosterone to dihydrotestosterone (DHT), resulting in a significant decrease in DHT levels. The usual dosage for the treatment of hair loss is 1 mg/day, but as little as 0.2 mg/day results in decreased scalp and serum DHT levels. Such decreases may not correlate clinically with changes in hair loss. Improvement can be seen as soon as three months after beginning finasteride, but for many men, it takes longer. Discontinuation results in full reversal within six months, leaving the patient where he would have been had he not used the medication at all.

Minoxidil and finasteride can act synergistically. Some patients have found that ketoconazole shampoo used with minoxidil can increase hair growth, but further studies are needed.

Hormone-antihormone therapies

Women whose hair loss is related to abnormal hormone levels can benefit from hormonal or antihormonal therapies and adjunctive treatments, such as estrogen (hormone replacement or oral contraceptives) or spironolactone, an aldosterone antagonist with antiandrogenic effects. Spironolactone works well as a treatment for hirsutism and may slow hair loss in women with androgenetic alopecia, but it does not stimulate hair regrowth. Estrogen may help to maintain hair status in women with androgenetic alopecia, but it does not help with regrowth. All these medications have a variety of side effects and should not be used by pregnant women. Other antihormonal treatments exist. Few controlled studies have examined the many non-FDA-approved hair growth agents, such as cyproterone acetate (not available in the United States), progesterone, Tagamet (cimetidine), and multiple nonprescription and herbal products.

Surgical alternatives

Surgical options comprise follicular transplantation, scalp reduction (removal of the affected scalp area), and rotation (lifting and rotation of a portion of hairy scalp to an area of baldness). While these techniques are effective for the properly chosen patient, they are also expensive.

Dr. Scheinfeld is assistant attending and chief of the inpatient consultation service at St. Luke’s- Roosevelt Hospital Medical Center, Department of Dermatology, and assistant clinical professor of Dermatology at Columbia University, both in New York City.