Apart from attacking follicles in the scalp, DHT also plays a leading role in the development of benign prostatic hyperplasia (enlarged prostate) and even prostate cancer itself.
The estrogens and synthetic progesterones, such as medroxyprogesterone acetate and chlormadinone acetate (26), have antiandrogenic properties that are the basis for their use against benign or malignant hyperplasia of androgen-dependent tissues such as the prostate.
Although the disease is occasionally caused by tumours or by hyperplasia of the adrenals, in most instances it is not.
It has been suggested that the disease results from excessive adrenocorticotropic hormone (ACTH) from the pituitary; in rare cases when the level of ACTH is not elevated, it is thought that autoantibodies to ACTH receptors cause the hyperplasia.
Simple benign hyperplasia (overgrowth) of the epidermis such as is commonly seen in infantile eczema often appears as lichenification, a term used to describe a thickening of the epidermis in which the normal surface markings of the skin are greatly exaggerated.
Thyrotropin regulates the thyroid gland through a feedback relationship similar to that for ACTH; thyrotropin increases the secretion of the hormones from the thyroid gland and, if its action is prolonged, evokes increase in cell number (hyperplasia) and increase in size of the gland.
Successful removal of the adrenal tumour usually results in reduction in blood pressure and cessation of potassium loss; patients with bilateral adrenal hyperplasia are treated with antihypertensive drugs.
In some cases, hypersecretion of insulin may be caused by diffuse hyperplasia (abnormal increase in cell number) of the islet cells or by a carcinoma (malignant tumour) of the islet cells.
Other, rarer forms of congenital adrenal hyperplasia result in varying degrees of hypertension or lack of sexual development, depending on the particular enzyme that is defective.
An example of hormone overproduction because of hyperplasia is hyperthyroidism, the disease produced by an excess of thyroid hormone.
Patients of any age with congenital adrenal hyperplasia are treated with cortisol or a synthetic hormone with similar properties, such as prednisone; some patients may also require mineralocorticoid treatment.
