Testosterone: The Rapunzel-Hormone

20. March 2012

A recent study shows that for women undergoing androgen replacement therapy head hair begins to regrow. This turns the current thesis on its head, according to which elevated testosterone levels are supposed to cause hair loss.

Many women complain, during and after menopause, of hair loss and thinning hair. Up until the present, increased testosterone levels were usually held responsible here. By contrast, in many studies no clinical or biochemical evidence of an androgen excess were to be found. Quite the contrary: In a recent study of women who received androgen therapy on account of androgen deficiency, no hair loss was observed. Rather, the hair began to grow again.

In the study, 285 pre-menopausal and post post-menopausal women participated. They were given for at least one year (12-56 months), because of their androgen deficiency, subcutaneous testosterone implants (of mean dose 133.3 mg). In order to investigate the effects of the therapy, among other things they answered questions about head and facial hair and age; BMI and serum testosterone levels were also measured. Before the start of hormone treatment, nearly 27% of the women reported of thinning hair. In these women, lower serum testosterone levels were measured than in women with a full head of hair. Four weeks after the start of the hormonal implant treatment, women were interviewed and a laboratory monitoring of serum testosterone levels was carried out.

Approximately 63% of women with previous hair loss indicated that hair had grown back. The serum testosterone levels however showed no significant differences between the three groups: women who prior to therapy had thinning hair and their hair grew back, women who prior to therapy had thinning hair and the hair did not grow, and women who did not report on thinning hair prior to treatment. However, it was observed that women whose hair did not grow during treatment had a higher BMI level than those women whose hair began to grow again. Women who did not respond to hormonal treatment with hair growth more frequently had other diseases such as Hashimoto’s thyroiditis, a strongly decreased TSH value or iron-deficiency anemia.

Is testosterone innocent?

The authors of the study, based on their results, have put the previously accepted opinion in question, wherein elevated levels of testosterone had been believed to promote woman’s hair loss. Rather, they suggest there being a positive anabolic effect of androgens on hair growth. According to their theory, with age decreasing testosterone levels – at age 40 it is only about half as high as at age 20 – would be responsible for thinning hair with women, because the postulated anabolic effect would be lost on hair growth in old age. However, as set out by the authors of the paper, their study was not designed to directly analyse the hair growth under androgen. A study in which the hair growth would be objectively assessed and measured, and not measured only on the basis of statements made by the study participants, would therefore be necessary. Nevertheless, the results add themselves to a number of previous studies in which no androgen excess was found in cases of hair loss.

The hair loss in women seems to have rather multifactorial causes. Genetic, as well as hormonal and psychological factors, may equally be involved. It is also possible that there are androgen-dependent and androgen-independent mechanisms, which have differing consequences for hair growth, according to conditions. During pregnancy, women tend to have very beautiful and luxuriant hair. This is due to high oestrogen levels which extend the growth phase of the hair. At the same time less hair falls out. After giving birth, oestrogen levels drop, which is something that has as a consequence, after two to three months, increased hair loss (postpartales Effluvium). The hair ends up back in its old growth cycle. During menopause the production of oestrogens decreases. The balance hormones maintain with each other is disturbed. The reason for hair loss might reside more in this part of the picture, than in the absolute concentration of one hormone.

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