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What is androgenetic alopecia (AGA)?

Hair loss can be very concerning to womenHereditary balding or thinning is the most common cause of hair loss. The tendency can be inherited from either the mother’s or father’s side of the family. Women with this trait develop thinning hair, but do not become completely bald. The condition is called androgenetic alopecia and it can start in the teens, twenties, or thirties. There is no cure, although medical treatments are available that may help some people.

Hereditary hair loss, or androgenetic alopecia, is marked by a progressive miniaturization of hair follicles, causing a shortening of the hair’s growth cycle. As the growth phase shortens, the hair becomes thinner and shorter. Eventually there is no growth at all. Because hereditary hair loss is gradual, the sooner treatment is started, the better the chances of results.

What Causes Androgenetic Areata?

Hair follicles contain androgen receptors. In the presence of androgens, genes that shorten the anagen phase are activated, and hair follicles shrink or become miniaturized. With successive anagen cycles, the follicles become smaller (leading to shorter, finer hair), and nonpigmented vellus hairs replace pigmented terminal hairs. In women, the thinning is diffuse, but more marked in the frontal and parietal regions. Even persons with severe androgenetic alopecia almost always have a thin fringe of hair frontally. The remaining hair configuration may resemble a monk’s haircut.

Women with androgenetic alopecia do not have higher levels of circulating androgens. However, they have been found to have higher levels of 5a-reductase (which converts testosterone to dihydrotestosterone), more androgen receptors, and lower levels of cytochrome P450 (which converts testosterone to estrogen).

Most women with androgenetic alopecia have normal menses, normal fertility, and normal endocrine function, including gender-appropriate levels of circulating androgens. Therefore, an extensive hormonal work-up is unnecessary. If a woman has irregular menses, abrupt hair loss, hirsutism, or acne recurrence, an endocrine evaluation is appropriate. In this situation, total testosterone, free testosterone, dehydroepiandrosterone sulfate, and prolactin levels should be obtained.

Because the hair loss in androgenetic alopecia is an aberration of the normal hair cycle, it is theoretically reversible. Advanced androgenetic alopecia, however, may not respond to treatment, because the inflammation that surrounds the bulge area of the follicle may irreparably damage the follicular stem cell.

AGA – Photo image of onset

Image photo of the onset of Androgenetic Alopecia in a female courtesy of www.aafp.org

Image photo of the onset of Androgenetic Alopecia in a female courtesy of www.aafp.org

Birth Control / Contraceptives and Hair Loss

BCPs contain a combination of estrogen and progestin. All BCPs now have one main source of estrogen — ethinyl estradiol. Ethinyl estradiol is a constant in the BCP equation but the part that changes is the progestin level. There are a number of different types of progestin and some of them are higher in androgenic value than others. I’ve compiled data from a number of different sources and come up with a handy chart that helps you identify which BCPs are high in androgens and which ones are lower. Remember that the higher the androgens, the more likely it will cause excessive hair loss, acne and hirsutism.

Click the image to view the full PDF file.

Click the image to view the full PDF file.

How is Androgenetic Areata (AGA) treated?

Only 2 proven, food and drug administration (FDA) approved medications are currently available for treatment of androgenetic alopecia: minoxidil and finasteride.

  • Minoxidil (5%): Rogaine: Topical minoxidil solution promotes hair growth in several conditions in which the hair follicle is small and not growing to its full potential. Minoxidil is FDA-approved for treating male and female pattern hair loss. It may also be useful in promoting hair growth in alopecia areata. The solution, applied twice daily, has been shown to promote hair growth in both adults and children, and may be used on the scalp, brow, and beard areas. With regular and proper use of the solution, new hair growth appears in about 12 weeks.

    Although the method of action is essentially unknown, minoxidil appears to lengthen the duration of the anagen phase, and it may increase the blood supply to the follicle. Regrowth is more pronounced at the vertex than in the frontal areas and is not noted for at least 4 months. Continuing topical treatment with the drug is necessary indefinitely because discontinuation of treatment produces a rapid reversion to the pretreatment balding pattern.

    Patients who respond best to this drug are those who have a recent onset of androgenetic alopecia and small areas of hair loss. The drug is marketed as a 2% or a 5% solution, with the 5% solution being somewhat more effective. A recent 48-week study compared the 2 strengths in men. Findings indicated that 45% more regrowth occurred with the 5% compared with the 2% solution. In general, women respond better to topical minoxidil than men. The increase in effectiveness of the 5% solution was not evident for women in the FDA-controlled studies. Subsequent studies have shown at best a modest advantage to the higher concentration in women. In addition, the occurrence of facial hair growth appears to be increased with the use of the higher-concentration formulation.

  • Finasteride: Propecia: Finasteride is given orally and is a 5 alpha-reductase type 2 inhibitor. It is not an antiandrogen. The drug can be used only in men because it can produce ambiguous genitalia in a developing male fetus. Finasteride has been shown to diminish the progression of androgenetic alopecia in males who are treated, and, in many patients, it has stimulated new regrowth.

    Although it affects vertex balding more than frontal hair loss, the medication has been shown to increase regrowth in the frontal area as well. Finasteride must be continued indefinitely because discontinuation results in gradual progression of the disorder. A study in postmenopausal women indicated no beneficial effect of the medication in treating female androgenetic alopecia.

  • Exogenous Estrogen: In the past, exogenous estrogen was used to treat androgenetic alopecia. This treatment is used less often now, because minoxidil is more effective. In fertile women with androgenetic alopecia who request oral contraception, it is important to select a pill containing the least androgenic progestin, such as norgestimate (in Ortho-Cyclen, Ortho Tri-Cyclen), norethindrone (in Ovcon 35), desogestrel (in Mircette), or ethynodiol diacetate (in Demulen, Zovia).
  • Hair Transplantation: Hair transplants involve removing healthy hair follicles from one area of the scalp and transplanting them to the bald areas. Surgical treatment of androgenetic alopecia has been successfully performed for the past 4 decades. Although the cosmetic results are often satisfactory, the main problem is covering the bald area with donor plugs (or follicles) sufficient in number to be effective. Micrografting produces a more natural appearance than the old technique of transplanting plugs. Patients with less than 40 follicular units/cm2 in their donor areas are poor candidates for the procedure. Scalp reduction has been attempted to decrease the size of the scalp to be covered by transplanted hair. However, the scars produced by the reduction technique often spread and become more noticeable with time.

    Hair weaving techniques are available, and, together with hairpieces, they offer the patient a prosthetic method of coverage.

  • Spironolactone: Aldactone: This drug is a weak competitive inhibitor of androgen binding to androgen receptors. It also decreases the synthesis of testosterone. For these reasons, orally administered spironolactone has been tried in the treatment of androgenetic alopecia, although questions remain about its usefulness. Spironolactone can be beneficial in women who also have hirsuitism. However, the FDA has not labeled this drug for the treatment of androgenetic alopecia.

Who is most likely to get AGA?

Men and women should look at both sides of their family tree for relatives with hereditary hair loss. The condition can be inherited from their mother, their father, or from both parents.

In the United States, 30 million women—or one in four—experience hereditary hair loss. Less frequent causes for hair loss in women include stress, illness, medication, diet, and pregnancy. But 70 percent of women with thinning hair can attribute it to hereditary hair loss.

Race neither increases nor decreases a person’s likelihood of experiencing hereditary hair loss. Hereditary hair loss affects all ethnicities.