Women develop Hirsutism and androgenic alopecia (lack of hair with a masculine pattern) when the levels of feminine hormones are low and the level of DHT (dihydrotestosterone), a virilising masculine hormone that is proportionally elevated, which can be verified by the levels of androstanediol glucuronide, the metabolite of DHT elevated in serum.
The deficit of thyroid and of cortisol can end up favouring the development of hirsutism.
Thyroid deficit leads to an inhibition of the aromatase enzyme and consequently the decrease of the transformation of testosterone into estradiol.
At the same time it stimulates the 5α-reductases enzyme, creating more DHT.
The decrease of cortisol and its production within the adrenal glands, lead to an increase of ACTH, a hormone that will stimulate the production of more cortisol.
This stimulation leads to the production of androgens (DHEA and androstenedione) by the adrenal glands that will lead to the virilisation with excess of hair, by means, the hirsutism.
By giving dexamethasone a glucocorticoid of extended action, we are able to “calm” the adrenal gland taking it to reduce the production of these hormones that are being improperly produced.
Also with an increase of Prolactin can lead to the increase of masculine hormones called the androgens, by indirect mechanism, and others. There are diverse possible organic causes, some serious, however it is important to proceed to the study of pathology so that it can foil diseases that might cause an increase of masculine hormones in women and consequently virilisation sometimes.
The Polycystic Ovary Syndrome (PCOS) or Congenital Adrenal Hyperplasia (CAH) of late emergence, are causes that fit within this group.
It can be manifested as an isolated complain, or as part of a more complex clinical picture such as obesity, diabetes, menstrual disturbs and infertility. Therefore, there is the need to study conveniently the patient, given the multiple etiologic hypothesis within this condition.
In the majority of the times though, what happens is hypersensitivity to the masculine hormones, not observing in fact an increase on the levels of these hormones but an increase on the activity of the receptors on the hair follicles, or an increase on its free forms in the blood. This is called idiopathic hirsutism.