It occurs because Cortisol "trumps" testosterone (see below).
While the body can live without
testosterone, it cannot live without cortisol. Excessive cortisol (especially the levels that people with Cushing's Disease or Cushing's Syndrome have) will kill you earlier in life than one's normal life expectancy would be (things like severe diabetes, severe cardivascular problems, more prone to cancers, etc., etc.)... but too little cortisol will kill you like "right now" (Adrenal Crisis or Adrenal Shock).
So if the HPA Axis is "reading" that there's too little cortisol in the body (even in cases where the HPA Axis is dysfunctional and there's actually too much cortisol), then the HPA Axis will continue frantically signalling for the secretion / production of yet more and more cortisol. And to continue to make the cortisol, the body will "steal" the "raw materials" from other hormone processes to keep producing cortisol. That includes (in males) DHEA and
testosterone (also lowers the production of many neurotransmitters such as serotonin, etc.).
Hypercortisolism is literally recognized medically as one of the causes of hypogonadism.
http://www.gsdl.com/home/assessments...de/index3.html Secondary hypogonadism can develop as a result of hypothalamic or pituitary disease, obesity, hypothyroidism or other causes. Some conditions, such as hypercortisolemia, AIDS and severe systemic illnesses, can trigger hypogonadism through a combination of both primary and secondary mechanisms. http://www.wellmax.org/NewsPub/Stori...892607709.html Hyperprolactinemia, hypercortisolemia, or hypothyroidism are also common... http://www.google.com/answers/threadview?id=450553 According to the Great Smokies Diagnostic Lab, these are the causes of
hypogonadism: chronic/systemic illness, surgery, chemotherapy, infections, premature aging, testicular trauma, stress, Kleinfelter's syndrome, autoimmune damage, tobacco and alcohol abuse, sleep apnea, excessive heat, obesity,
hypercortisolism, (certain) medications, hyperthyroidism, malnutrition http://neoteny.info/a/testosterone.html Two mechanisms can account for a lower gland production of the hormone: -- a persisting significant rise in the levels of circulating epiniphrine could induce a drop in the plasma levels of testosterone by means of reduced testicular production, with unchanged global metabolic clearance (32); --- hypercortisolemia, under the condition that it is prolonged enough, would reduce the plasma levels of testosterone (33,34). This normal profile (hypercortisolemia, hypotestosteronemia) is described in other stress conditions (35,36) and in Cushings's syndrome (37,38,39)... http://www.aace.com/pub/ep/199905ep.php The mechanism of glucocorticoid-induced muscle atrophy relies on the degradation of the myosin heavy chain (catabolic effect), the most important contractile protein in muscle, associated with a decrease of its synthesis (antianabolic effect). One of the contributing factors in the development of muscle atrophy is hypogonadism that is induced by long-term glucocorticoid use. http://www2.mcdaniel.edu/Biology/EPS...ss/stress.html Glucocorticoids (technical name for cortisol in the body) also inhibit the testes and ovaries directly, hindering production of the male and female sex hormones testosterone, estrogen, and progesterone. http://www.nutrition4health.org/NOHA...rdingAging.htm Conditions which require large amounts of cortisol create a drain on our capacity to produce adequate hormones. To provide the excess cortisol needed to respond to conditions such as pain and inflammation, the body diverts the production of our sex hormones into the production of cortisol. In particular, the body "cannibalizes" our (WOMEN'S) sex hormone progesterone to make additional cortisol... This decrease in our progesterone often leaves us with low progesterone in comparison to our estrogen or testosterone and leads to conditions of "estrogen dominance" (is doing the same thing with testosterone in men - LRS)
From some general notes:
Also keep in mind that the body corrects abnormal cortisol levels by "stealing" from the sex hormones. The biochemists call this "pregnenelone steal," because pregnenelone is the precursor of BOTH cortisol and the sex hormones. Thus, abnormal cortisol by its nature causes derangements in the sex hormone balance. Cortisol is a steroid hormone that governs catabolism (destructive) actions throughout the body. Testosterone is a steroid hormone that promotes anabolic (building) actions. Head-to-head, cortisol trumps testosterone. What controls cortisol? -- the reaction of the autonomic nervous system to acute and chronic stress...
Larry