专家视点：女性脱发的分类与治疗

旧金山——女性脱发的模式分为3个明显不同的阶段，这与开始脱发时的年龄有关，而未必都与雄激素水平相关。

加州大学旧金山分校的皮肤病学教授Vera H. Price博士在太平洋皮肤病学会(PDA)年会上指出，从青春期到40岁之间，女性头发变细倾向于由雄激性脱发引起，后者是一种常见的遗传情况，由雄激素在遗传易感人群中引发，男女均可发生。而在≥60岁的女性中，头发变细可能与年龄相关，即“衰老性”脱发，这与雄激素性脱发有明显差异，因为前者并不是由二氢睾酮介导的。

然而，45~55岁这一脱发阶段正在逐渐为人们所熟知。这一阶段又被称为“女性模式脱发”，在此阶段中，雄激素的角色不太清晰，其他的激素性和非激素性因素可能发挥着一定作用。

这三个阶段都表现出相似的组织病理学特征，即毛囊萎缩、泌脂腺体正常，并且没有明显炎症。然而，识别和认识这三个阶段有助于更好地予以治疗。

例如，米诺地尔治疗适用于所有三个阶段的脱发，但是通过超适应证使用非那雄胺阻断雄激素对衰老性脱发是无效的。“我不会对60岁以上的男、女性患者使用该药。”服用非那雄胺5 mg/d治疗良性前列腺增生的成千上万的男性并未出现头发再生，证明衰老性脱发并不是由二氢睾酮介导的。

·雄激素性脱发

为了在女性中筛查出可疑的雄激素性脱发，应核实有无月经不规律、不孕症、多毛症、严重囊肿性痤疮、乳溢和女性男性化。“假如没有这些情况，你就不必做激素检测”，因为脱发并不是雄激素性的。


Vera H. Price博士

假如患者有上述情况中的任意一项，就应当检测睾酮、硫酸脱氢表雄酮(DHEAS)和催乳素的水平。

在所有的脱发患者中，都应获取全血细胞计数，核实促甲状腺激素(TSH)、铁蛋白和25-羟基维生素D水平正常；后两者是正常的毛发周期所必需的。Price博士补充道，一定要特别指定检测铁蛋白水平，原因是“铁检查”并不包含铁蛋白水平。

·女性模式脱发

女性模式脱发的发病机制尚不完全清楚。当女性经历绝经期时，头发生长参数会发生改变：头发生长速度变慢，生长期/静止期比率下降，头发直径变小。

我们需要进一步明确可能影响女性模式脱发的激素性与分子性因素，包括雌激素、雌激素受体(ER)β、芳香酶、5α还原酶、二氢睾酮和雄激素受体的潜在作用。

·衰老性脱发

颇有些讽刺意味的是，Price博士把衰老性脱发称为“智慧相关性”脱发。雄激素性脱发和衰老性脱发的基因表达特征是不一样的。在前者中，头发生长周期基因呈差异性表达；而在后者中，全身衰老基因呈差异性表达。这提示它们是两种截然不同的疾病。

·治疗

不论对于哪个阶段的脱发，米诺地尔(落健)在长期合理使用的情况下可能是有帮助的。Price博士建议，每天直接对干燥头皮(而不是在淋浴后短时间内)涂抹2%或5%的溶液，并且轻轻涂匀整张头皮。在米诺地尔被头皮吸收的过程中，不要对头发喷雾、抹摩丝或用吹风机吹干。每日1次5%米诺地尔泡沫也已获准用于女性，泡沫不像溶液那么油腻而且吸收更快。

值得一提的是，超适应证使用非那雄胺1 mg/d阻断雄激素来治疗确诊为雄激素性脱发的患者的做法，禁用于可能已经或将要怀孕的女性，原因是该药可引起男性胎儿尿道下裂。在对女性患者使用非那雄胺时应确定其是否已经绝经，如果是绝经前女性，应同时使用口服避孕药。

“我确实会对女性患者使用非那雄胺，但我会非常小心。我只对接受了子宫切除术或输卵管结扎术的女性使用该药，从而保证她们不会再怀孕。”

对于符合条件的患者，在经济能力允许的情况下，可以联合使用米诺地尔和非那雄胺。

雄激素受体抑制剂螺内酯也已被用于延缓雄激素性脱发引起的头发变细，剂量为200 mg/d。有数据显示，螺内酯50~200 mg/d可成功治疗痤疮和多毛症，但尚无循证研究显示其有助于头发再生。“我很少用螺内酯治疗雄激素性脱发。它并不能使头发生长。我想，它之所以被大量使用是因为人们对米诺地尔还不熟悉，或者不知道在没有妊娠可能性的情况下可以使用非那雄胺。”

Price博士报告称与Allergan和Follica有经济利益关系，但这两家公司均与本文的主题无关。

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By: SHERRY BOSCHERT, Internal Medicine News Digital Network

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.

"I use very little spironolactone for androgenetic alopecia," Dr. Price said. "It will not grow hair. I think it’s used a lot because people aren’t familiar with minoxidil or don’t know about using finasteride if there’s no possibility of pregnancy."

Dr. Price reported having financial associations with Allergan and Follica, neither of which was pertinent to this topic.