SAN FRANCISCO – Three distinct stages of pattern hair loss in women are related to the age of onset, and are not necessarily androgen related.
Between puberty and age 40 years, hair miniaturization in females tends to be caused by androgenetic alopecia, a common hereditary thinning or balding induced by androgens in genetically susceptible people of both sexes. By contrast, women in their 60s or older may develop hair thinning from age-related, or "senescent" alopecia, which is distinct from androgenetic alopecia because senescent alopecia is not mediated by dihydrotestosterone, Dr. Vera H. Price said at the annual meeting of the Pacific Dermatologic Association.
However, a newly identified stage that often occurs between 45 and 55 years of age is gaining popularity in the lexicon of hair loss. In this stage, called "female pattern hair loss," the role of androgens is less clear-cut, and other hormonal and nonhormonal factors may play a role, said Dr. Price, professor of dermatology at the University of California, San Francisco.
All three stages show similar histopathology, with follicular downsizing, normal sebaceous glands, and no significant inflammation. However, recognizing and understanding the three stages help inform management, said Dr. Price.
Treatment with minoxidil is suitable for all three stages of hair loss, for example, but androgen blockade via off-label treatment with finasteride is not helpful in senescent alopecia. "I don’t use it after 60 years of age in women or men," she said.
Millions of men who have taken finasteride 5 mg/day for benign prostatic hypertrophy have not regrown scalp hair, evidence that senescent alopecia is not dihydrotestosterone mediated, she noted.
• Androgenetic alopecia. To screen for suspected androgenetic alopecia in women, check for menstrual irregularities, infertility, hirsutism, severe cystic acne, galactorrhea, and virilization. "If none are present, you do not have to do a single hormonal test" because it’s not androgenetic alopecia causing the hair loss, Dr. Price said.
If any one of those conditions is present, however, check levels of testosterone, dehydroepiandrosterone sulfate (DHEAS), and prolactin.
In all hair loss patients, get a complete blood count and check for normal levels of thyroid-stimulating hormone (TSH), ferritin, and 25-hydroxyvitamin D; the latter two are required for a normal hair cycle. Be sure to order the ferritin level specifically, because ordering "iron studies" won’t include a ferritin level, she added.
• Female pattern hair loss. The pathogenesis behind female pattern hair loss is not well understood. As women go through menopause, hair growth parameters change. The hair growth rate slows, the anagen/telogen ratio decreases, and hair diameters become smaller, Dr. Price explained.
Hormonal and molecular factors that may influence female pattern hair loss need to be better defined, including the possible roles of estrogen, estrogen receptor (ER)-beta, aromatase, 5-alpha-reductase, dihydrotestosterone, and androgen receptors, she said.
"When we understand that, we’ll understand this group a little more clearly," she added. "I’ve always been puzzled a little bit when the onset is in this age group."
• Senescent alopecia. "I call it ‘wisdom-related’ alopecia," quipped Dr. Price. The gene expression profiles of androgenetic alopecia and senescent alopecia differ. In the former, hair growth cycle genes are differentially expressed. In the latter, systemic senescent/aging genes are differentially expressed, suggesting these are two distinct disorders.
• Management. For any stage of hair loss, minoxidil (Rogaine) may help if used properly over an extended period of time, said Dr. Price. Apply the 2% or 5% solution every single day directly to a dry scalp, not right after a shower, and spread it gently across the scalp, she advised. Give minoxidil time to absorb without spraying, moussing, or blow-drying the hair while it absorbs. Once-daily minoxidil foam 5% also has been approved for women and is less oily and absorbed faster.
Of note, androgen blockade via off-label oral finasteride 1 mg/day for confirmed androgenetic alopecia is contraindicated in women who may be or may become pregnant because it will cause hypospadias in a male fetus, said Dr. Price. Prescribe concurrent oral contraception in premenopausal women or make sure the woman is postmenopausal when using finasteride.
"Do I use it in women? I do, but I’m very careful," she said. "They have to be post hysterectomy or post tubal ligation. I want to be certain that they’re not going to conceive."
In appropriate patients, minoxidil and finasteride could be used together if the patient can afford it, she added.
Spironolactone, an androgen receptor inhibitor, also has been used in a dose of 200 mg/day to retard hair thinning due to androgenetic alopecia. Data show that spironolactone 50-200 mg/day can be used successfully to treat acne and hirsutism, but there are no evidence-based studies showing that it helps hair regrowth.