Disorders of Hair: Androgenetic Alopecia

by admin on November 8, 2007

Disorders of Hair: Androgenetic AlopeciaI came across this article today while doing some hair loss research on the internet, and I thought it covered a lot of questions that women have about hair loss. The article is about both male and female pattern hair loss and provides a good overview. It was published on medscape from ACP Medicine Online. Here it is:

David A. Whiting, M.D.

Androgenetic alopecia is the common type of nonscarring hair loss affecting the crown. It results from a genetically determined end-organ sensitivity to androgens. It is often referred to as common baldness, male-pattern alopecia, and female-pattern alopecia.

Epidemiology and Pathogenesis

Androgenetic alopecia affects at least 50% of men by 50 years of age and 50% of women by 60 years of age.6,7 Males have more androgen than females and therefore are usually affected earlier and more severely. Male-pattern alopecia often starts between 15 and 25 years of age. Male-pattern alopecia has two characteristic components, bitemporal recession and vertex balding [see Figure 1 — omitted], which in pronounced cases can progress to complete balding of the crown.6,7 Female-pattern alopecia is more likely to start between 25 and 30 years of age (or sometimes later, after menopause). It is characterized by an intact frontal hairline and an oval area of diffuse thinning over the crown [see Figure 2 — omitted]. Bitemporal recession in women is much less obvious than it typically is in men, or it can be nonexistent. In general, androgenetic alopecia in women progresses to mild, moderate, or severe thinning but not to complete baldness. The best predictor of outcome is the degree of progression in affected relatives.

Androgenetic alopecia is an autosomal dominant disorder with variable penetrance. Susceptible hairs on the crown are predisposed to miniaturize under the influence of androgens, notably dihydrotestosterone. In both sexes, miniaturization results from a shortening of the anagen cycle, from years to months or weeks. Miniaturized hairs are characterized by reduced length and diameter; this accounts for the appearance of hair loss.8 Androgenetic alopecia largely spares the back and sides of the scalp.

Diagnosis

The diagnosis of androgenetic alopecia is usually obvious from the clinical pattern of hair loss from the top of the head.9 In some men, a female pattern of alopecia (see above) causes diagnostic confusion but has no other significance. In women, a male pattern of alopecia (i.e., bitemporal recession and vertex balding) occurring with menstrual irregularities, acne, hirsutism, and a deep voice is significant. The virilism indicates significant hyperandrogenism, the cause of which must be identified and treated [see 3:IV The Adrenal — omitted].

Scalp biopsies are rarely necessary to diagnose androgenetic alopecia. Biopsies cut horizontally are sometimes useful, however, in differentiating female-pattern alopecia from chronic telogen effluvium (see below).Treatment

Depending on the severity of the condition, management of androgenetic alopecia ranges from watchful inactivity to medical and surgical treatment, or a hairpiece or wig may be used in the most refractory cases.

Topical Therapy

The Food and Drug Administration approved topical 2% minoxidil for use in men in 1987 and in women in 1989. Minoxidil is applied twice daily with a dropper, spread over the top of the scalp, and gently rubbed in. The drug should be tried for at least a year. Minoxidil acts by initiating and prolonging anagen. It produces visible hair growth in approximately one third of male and female patients, fine-hair growth in approximately one third, and no growth in approximately one third. It is more effective as a preventive agent, retarding hair loss in approximately 80% of patients.6

Topical 5% minoxidil, which was approved for use in men in 1997, produces visible hair growth in 45% of patients in less time than the 2% solution. Both concentrations are available over the counter. Side effects are not significant and include scalp irritation and increased facial hair.10 The medication has to be continued indefinitely.11

Systemic Therapy

Oral finasteride, at a dosage of 1 mg/day, was approved by the FDA for the treatment of male-pattern alopecia in 1997. Finasteride is a powerful type II 5?-reductase inhibitor that prevents formation of dihydrotestosterone in the prostate gland and in the hair follicle. It reduces circulating dihydrotestosterone by 65% to 70%. When administered at a dosage of 1 mg/day for 2 years to male patients with androgenetic alopecia who are between 18 and 41 years of age, finasteride grew visible hair in 66% and prevented further hair loss in 83%.12 The efficacy of finasteride was maintained in a 5-year study.13 Hair-weight studies have shown that finasteride increases hair length and diameter, producing better coverage from existing hairs.14

Side effects in men are minimal and include lack of libido, lack of potency, and mild reduction in semen in approximately 0.5% of patients. These effects are reversed when the drug is stopped and often disappear as the drug is continued. A 1-year trial of finasteride at a dosage of 1 mg/day in postmenopausal women failed to show any positive effects.

Because of the likelihood of finasteride to cause severe side effects in the male fetus, the drug is contraindicated in premenopausal women.

Therapy for Hair Loss in Women

Topical minoxidil is currently the best available treatment for androgenetic alopecia in women.10,15 However, various antiandrogenic drugs have been used. Oral contraceptives (e.g., ethinyl estradiol-ethynodiol diacetate [Demulen], desogestrel-ethinyl estradiol [Desogen], and ethinyl estradiol-norgestimate [Ortho Tri-Cyclen]) can reduce hair loss and occasionally lead to slight hair growth.6 Oral spironolactone (Aldactone) in dosages of 75 mg/day to 200 mg/day can produce androgen blockade. Dexamethasone in dosages of 0.125 mg/day to 0.5 mg/day can suppress adrenal overactivity. Cyproterone acetate, which is not available in the United States, is not as effective as minoxidil in female pattern hair loss unless other signs of hyperandrogenism are present.16

Therapy for Refractory Cases

In patients who do not respond to the treatments listed above, the next step may be hair transplantation. Micrografts and minigrafts can produce a good cosmetic appearance in patients who have a sufficient reserve of hair on the back and sides of the scalp.17 If all therapies fail, a hairpiece may be an option.

David A. Whiting, M.D., Associate Professor of Dermatology, University of Texas Southwestern Medical Center at Dallas, Medical Director, Baylor Hair Research and Treatment Center.

I think this is only an excerpt of the full article and there was a link provided to purchase the full article with the images. If anyone is interested in doing so here is the link.

{ 5 comments… read them below or add one }

Ramona April 24, 2008 at 6:38 am

Great article, the link to purchase the full disclosure takes your money but you click another link to retrieve and it doesn’t work. I am still in talks with the WebMD to figure out what’s wrong. They have bad links and bad email addresses too.

sabby555 February 22, 2010 at 11:34 pm

I went to see Dr. Whiting in Dallas. It was well worth the trip for me. I got my hair loss diagnosed, and there is a treatment plan for all types of hair loss. It was a relief to finally get a diagnosis and decide on treatment instead of watching and waiting which I had been doing for 5 months.

LH April 15, 2010 at 8:47 am

I saw Dr. Whiting winter of 2009. He’s a terrible listener, very arrogant, very old (83 at that time), deaf, and the biggest waste of money and time. I had to go elsewhere for the correct diagnosis and treatment. He was very proud to show me he had written a book, though, and tooting his own horn. Too bad that horn should not be practicing medicine any more. He should stick to writing articles. If you’re considering going to Dr. Whiting, don’t. Find someone who knows what they are doing.

SA August 7, 2010 at 8:42 pm

Dear LH:
where did you go to get your hair loss diagnosed? Who was the second dermatologist you saw?

CR February 16, 2016 at 11:46 am

I concur with LH. A year of my time and money wasted. The doctor couldn’t remember from one minute to the next where I was in my treatment with h the chart right in front of him. Not familiar with the emerging treatments. His time has past.

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