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Endocrine Perspective by GEOFFREY P. REDMOND, M.D.
Past Endocrine Columns
Dear Dr. Redmond: I have many clients who express concern to me about loss of hair from the scalp. I understand that this can be an effect of testosterone. Lately I have been hearing about estrogen and hair. Can both of these hormones be involved? You are correct that most female hair loss is related to hormones and that testosterone and estrogen both play a role. Unfortunately, many doctors are not aware of this and so finding a clear explanation and effective treatment can be a frustrating process. Let’s consider how the hormonal cause of hair loss can be determined and then how this helps determine what treatments might be effective. Hormonal hair loss has a distinctive pattern. The top of the scalp is most affected. There may be thinning on the sides but this is generally less than on top. Often the first sign is widening of the part or a thinner ponytail. Usually the front hairline is preserved, unlike men in whom the hairline almost always recedes. Because the hairline does not change, female hair loss is usually not noticeable by someone sitting facing you. This is good, except that it is a common reason why doctors often do not believe their patients who tell them they are losing hair. The temples also may have some thinning, in a triangle shape with the apex pointing backwards. This is usually easily covered by the surrounding hair. Some women fear that the thinning will progress backwards to the back of the scalp but this never happens. A little thinning at the temples by itself is normal. The pattern I have described is that of hormonal hair loss. The most common non-hormonal hair loss is alopecia areata. This is caused by the person’s own immune system attacking her hair follicles. Occasionally it is associated with a thyroid condition called Hashimoto’s thyroiditis but the hair loss is not caused by the thyroid dysfunction. The usual treatment is injection of a form of cortisone into the scalp by a dermatologist. With alopecia areata there is complete loss of hair from discrete areas or sometimes even the entire scalp and other areas such as eyebrows. In androgenic alopecia, there is always some hair left, even if it is very sparse. So alopecia areata usually looks quite different from hormonal alopecia. Hormonal alopecia is usually referred to as “androgenic” or “androgenetic” alopecia. The first indicates a role for androgens (testosterone and related hormones). The second also implies a genetic factor. I avoid the latter term because many think that if a condition is genetic, it cannot be treated. This is absolutely not true. Genetic conditions, including alopecia, are often treatable. The other problem with the term “androgenic” is that it refers to a pattern of hair loss which can also be caused by low estrogen. The pattern is the same whether the cause is increased testosterone action or a fall in estrogen. Another term commonly used is “telogen effluvium.” This implies a period of increased shedding which will be temporary. However most alopecia is not temporary and waiting just delays getting treatment. Accordingly, I do not regard telogen effluvium as a meaningful diagnosis. Both testosterone and estrogen have effects on hair but the effects are opposite. Testosterone causes the hair follicles to become less active. The hairs get finer and finer until they cannot be seen at all. Men have testosterone levels ten to twenty times higher than women; that is why all men have at least some hair thinning. However, as everyone notices, some men have nearly a full head of hair while others have next to none. The difference is not due to differences in testosterone levels but to differences in the way the hair follicles react to testosterone. Some have follicles which are overly sensitive and so inactivate easily with just a whiff of testosterone. Others have follicles which are unfazed by the hormone. This difference in follicle sensitivity is in part genetic. We’ll see why this is important for women in a moment. What about estrogen and hair? An easy way to understand how estrogen affects the body is that it has a nurturing effect. It stimulates the growth of breast, uterus and other female organs beginning at puberty as well as opening up blood vessels so that they can bring more nutrients to tissues. The nurturing effect of estrogen is especially important for hair. Estrogen causes hair to grow faster and stay on the head longer resulting in a more abundant head of hair. When estrogen levels drop, hair grows slower and sheds sooner — resulting in sparser hair. Estrogen also nurtures the skin making the collagen – the protein which gives strength to the skin – thicker. Estrogen and testosterone then have opposite effects on hair. How then do we tell whether an individual woman’s hair loss problem is due to testosterone or to estrogen? In my practice I have seen several thousand women with hair loss problems over the past twenty years which gives me familiarity with all the possible variations. I can give some general guidelines but the diagnosis needs to be made by a physician experienced with female hair loss. First is age. Testosterone levels begin to rise when a girl starts to develop, usually between eight and twelve. However alopecia due to testosterone usually develops gradually so that it may not be noticeable until the mid-twenties or even thirties though I have seen it as early as fourteen. Estrogen goes up at the same age but usually does not go down until perimenopause approaches. So if hair loss begins in the mid-thirties or earlier, the cause is likely to be testosterone. This is even more likely if there are other signs of testosterone effect on the skin such as increased facial and body hair and oily skin or acne. When alopecia begins in the forties, especially if the androgenic skin changes just mentioned are not present, lowering estrogen levels are the more likely cause. When hair loss begins at the same time as menopausal symptoms, a relation to falling estrogen levels is even more probable. Before the forties, if a woman has regular periods, low estrogen is unlikely. Women on oral contraceptives will not have low estrogen because the pill supplies it. Lab tests are less helpful than one might think. Even when the culprit is testosterone, levels of this hormone may be normal because the problem is increased sensitivity of the follicles, not high levels of the hormone. With perimenopause, estrogen levels fluctuate widely so a single normal level does not mean that levels are too low at other times. Treatment of hormonal alopecia of course depends on the cause. When it is due to high testosterone or to testosterone sensitivity, medication to lower or block testosterone usually helps. These include certain “hair friendly” oral contraceptives as well as medications which block testosterone such as spironolactone (Aldactone®). When the cause is falling estrogen, the only known effective treatment is hormone replacement. A higher than minimum dose may be required to restore hair growth. Whether to go on HRT is a difficult decision nowadays. I discussed the issues regarding HRT in detail in my previous two columns so I will not repeat that here. Estrogen can often help hair but there are other issues to consider in whether to take estrogen. With only rare exceptions, it is possible to determine the hormonal factors producing hair loss and design treatment to correct them. Women with alopecia should not let themselves be discouraged but should seek out a knowledgeable physician to help them.
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