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Dear Dr. Redmond:
Testosterone is the sole trigger of hirsutism and acne (and the main cause of alopecia when it begins before age 40). This potent hormone can be measured in several ways; unfortunately no single test tells the whole story. Moreover, testosterone levels are commonly misconstrued, and I never accept a blanket statement that this test is “normal.” To understand how testosterone levels are properly interpreted, you need to know some things about this hormone that most doctors do not know, though there is nothing truly arcane about them. Testosterone is measured in three different forms. Ninety-eight percent of testosterone in the blood circulates attached to a protein called SHBG (sex hormone binding globulin) that also carries estrogen. When hormones are bound to SHBG they are out of the action, safely trapped in the bloodstream and so unable to escape into tissues. Only about 2% of testosterone is not attached to SHBG, and is free to diffuse into tissues, including oil glands and hair follicles: This is referred to as free testosterone (FT). Total testosterone
sounds like it would be the most important one, but it is actually FT that
affects a woman’s body. Unfortunately, many of the assays for FT are inaccurate,
so test results give only a general idea of the actual level. SHBG can be
measured, but is less useful. Testosterone lowers SHBG; as levels of this hormone go up, more and more is free to slip out of the blood into the tis sues — where it wreaks its havoc. The next problem in making sense of testosterone levels is that different laboratories give different normal or ‘reference’ ranges, and we it’s unclear why these vary so much. The upper normal for total testosterone ranges from 55 to 120 mcg/dL. But a level of 100 might be considered “a very high level of testosterone” at one laboratory, and judged to be “normal” at another. My own opinion — based on seeing thousands of testosterone results in more than 20 years of practice — is that when the level approaches or exceeds 50, unwanted effects such as acne, hirsutism and androgenic alopecia are common. The unmeasured variable is, of course, how each individual reacts to testosterone. The more sensitive a woman’s oil glands and follicles are to this hormone, the lower the level at which it will adversely affect her skin and hair. Like everything else hormonal, testosterone fluctuates. If blood happens to be drawn during a low point, the result will be normal for a woman who may have high levels at other times. Testosterone tends to be highest in the morning, so the best time to have the test drawn is between 8 a.m. and 10 a.m. Even levels obtained later in the day can be helpful, however. So, what’s really normal? Before accepting a result as normal, we must ask, “normal for what?” This is a particular point of confusion with respect to hormone tests. A testosterone level within the normal range means that the ovary and adrenal are not over-producing this hormone. When the level is significantly elevated it is essential to find out the source and cause of the over-production. (Possible causes might include polycystic ovary syndrome (PCOS), late-onset adrenal hyperplasia, thecal cell hyperplasia, and tumors (fortunately, extremely rare). When testosterone is not elevated it is good news because we are reassured that the function of ovaries and adrenals is relatively normal, though a normal level does not rule out mild PCOS. The most important thing to be borne in mind (unfortu nately not widely known), is that for some women “normal” levels of testosterone can still cause damage: The test only tells us what the ovaries and adrenals are doing — it says nothing about how the body responds. For some women even a borderline-high testosterone level of 50 will not cause noticeable effects. For others, who have the bad luck to be ultra sensitive to this hormone, even a much lower level will leave its mark on skin and hair. Testosterone changes over time. In women, levels peak in the late teens and early twenties, then gradually decline. Unfortunately, laboratory reference ranges rarely include a breakdown by age, which further obscures the meaning of the test because we need to know what the level means for the patient’s actual age. The length of exposure to high levels of testosterone is another critical variable. A total testosterone level of 50 that lasts for a year is far less damaging than a level of 45 that persists for a decade. Of course there is no way to measure what past levels might have been. That is why I emphasize that tests tell part of the hormonal story, but not all of it. The most important thing to be kept in mind is that a “normal” testosterone level does not mean that this hormone is not the cause of acne, hirsutism or alopecia. Sometimes women are disappointed when their result is normal, because they think that it means the cause cannot be found. Actually, testosterone is always the cause of acne and hirsutism, and often of alopecia. Even when it is normal, treatment to lower the level or block its effects on skin and hair can be affected. |
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