Dehydroepiandrosterone, or DHEA, is a steroid hormone naturally produced in the bodies of both men and women. Most of the circulating DHEA comes from the adrenal gland, but both testes (testicles) and ovaries produce some as well. DHEA acts as a weak androgen, although its normal role in the body is not completely clear. Some evidence suggests that DHEA can be used as a drug to treat several medical conditions.
Synthesis
Like all steroid hormones, DHEA is made from cholesterol in several steps. The adrenal gland, the Leydig cells of the testis, and the thecal cells of the ovaries all produce some DHEA using the same pathway. The cells convert cholesterol to pregnenolone, which then converts to 17-alpha-hydroxypregnenolone. Under the influence of the enzyme called Cyp17, 17-alpha-hydroxypregnenolone becomes DHEA. DHEA and its sulfate (DHEAS) are the primary hormones made by the adrenal cortex. While the testis makes high levels of DHEA, most of it is immediately converted into testosterone in the Leydig cells; very little DHEA is secreted into the blood. The ovaries make and secrete very low levels of DHEA.
Function
DHEA is considered a "weak" androgen, relative to the more potent androgens like testosterone and and dihydrotestosterone (DHT). Functionally, this means that DHEA does not bind strongly to androgen receptors on tissues that respond to androgens, so that DHEA has only a modest effect on those tissues. Some tissues outside of the testis have the enzymes needed to convert DHEA to testosterone. However, this "peripheral conversion" produces only about 5 percent of all testosterone, according to "Endocrinology: An Integrated Approach."
Role
"Endocrinology: An Integrated Approach" says that the role of DHEA in normal body function is "ill-determined." DHEA is critical as a precursor to testosterone production within the testes. In men, the testes produce so much testosterone that circulating DHEA becomes physiologically insignificant. In women, adrenal androgens support the growth of normal pubic hair and axillary (underarm) hair.
Puberty
Although scientists are not exactly sure what brings on the changes of puberty, one theory proposes a role for DHEA. The adrenal gland produces significant amounts of DHEA. The theory suggests that at the time of adrenarche, the increase in adrenal activity that presages puberty, high levels of DHEA from the adrenal gland travel to the brain and tell hormone-producing neurons to release the master reproductive hormone called gonadotropin-releasing hormone (GnRH), which leads to maturation of the testes or ovaries.
Supplementation
DHEA is available as a prescription drug and has been used to treat a variety of conditions. However, the Mayo Clinic says that most of the uses do not have good enough evidence to conclude that DHEA is useful. Exceptions include use of DHEA for adrenal insufficiency, or Addison's disease; labor induction; systemic lupus erythematosus; and depression. Evidence suggests that DHEA is an effective therapy for these, although further studies are needed.
References
- "Endocrinology: An Integrated Approach"; S. Nussey and S. Whitehead; 2001
- Mayo Clinic: DHEA
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