Adrenal androgens secretion

In adrenogenital syndrome and adrenal virilism, an attempt may be made to suppress excess adrenal androgen secretion by inhibiting pituitary corticotropin production by means of prednisolone or dexamethasone. Suppression of androgen production is effective if there is adrenal hyperplasia, but not if an adrenal tumour is present. Hairiness, which women especially dislike in themselves, is often unaffected even though good suppression is achieved, and menstruation recommences. 

Age and familial factors in both men and women influence both plasma adrenal androgens (DHEA and DHEA-S). Adrenal androgen secretion starts to rise about the age of 9, peaks at about age 25, and declines after age 30. In the seventh decade of fife, the adrenal androgen concentrations fall to prepubertal concentrations. Thus in the elderly, the circadian variation in plasma DHEA is relatively blunted and dissociated from the circadian variation in cortisol. The adrenal contribution of serum androstenedione declines with age. DHEA and DHEA-S responses to stimulation with exogenous ACTH are... 

Mineralocorticoid and adrenal androgen secretion is also circadian and episodic in nature, but the dynamic swings in concentrations are not as pronounced as with cortisol. It is usually recommended, however, that blood samples for adrenal steroids be collected in the 0700 to 1000 hour tune frame for consistency in result interpretation. 

The responses of adrenal androgen secretion to ACTH stimulation are variable. Plasma DHEA and androstenedione increase threefold to fourfold after 90 minutes of stimulation with ACTH (i0 lg/m ). DHEA-S, on the other hand, increases 30% to 50% with ACTH administration. ACTH stimulation studies are not considered useful in evaluating hypoandrogenic disorders. 

Meilde AW, Daynes RA, Araneo BA. Adrenal androgen secretion and biologic effects. Endocrinol Metab Clin North Am 1991 20 381-400. 

Odell W, Parker J. Control of adrenal androgen secretion. In Genazzani AR. Adrenal androgens. New York Raven Press, 1980 27-42,... 

Parker LN. Control of adrenal androgen secretions. Endocrmol Metab Chn 1991 20 401-22. 

Adrenal hormone production is controlled by the hypothalamus and pituitary gland. Corticotropin-releasing hormone (CRH) is secreted by the hypothalamus and stimulates secretion of adrenocorticotropic hormone (ACTH), also known as corticotropin from the anterior pituitary. ACTH, in turn, stimulates the adrenal cortex to produce cortisol. When sufficient or excessive cortisol levels are reached, a negative feedback is exerted on the secretion of CRH and ACTH, thereby decreasing overall cortisol production. The control of adrenal androgen synthesis also follows a similar negative-feedback mechanism. 

Testosterone, the major androgenic hormone, accounts for 95% of the androgen concentration. The primary source of testosterone is the testes however, 3% to 5% of the testosterone concentration is derived from direct adrenal cortical secretion of testosterone or C-19 steroids such as androstenedione.17,18... 

Congenital enzymatic defects in the adrenal biosynthetic pathways lead to diminished cortisol and aldosterone production and release. In these conditions, corticotrophin secretion is increased, and adrenal hyperplasia occurs, accompanied by enhanced secretion of steroid intermediates, especially adrenal androgens. More than 90% of cases of congenital adrenal hyperplasia are due to 21-hydroxylase deficiency, which is cre-afed by mufafions in fhe CYP21 gene encoding fhe en-... 

Extreme clinical examples of androgen excess include central precocious puberty, the adrenogenital syndromes, and androgen-secreting adrenal, ovarian, or testicular tumors. Less severe problems include idiopathic hirsutism, premenstrual syndrome, and severe cystic acne. 

In humans, the most important androgen secreted by the testis is testosterone. The pathways of synthesis of testosterone in the testes are similar to those previously described for the adrenal and ovary (Figures 39-1 and 40-2). 

The adrenal glands play an important role in pubertal development. Termed adrenarche, the maturation of a prominent zona reticularis, the innermost layer of the cortex, begins around age six to eight in girls, resulting in increased secretion of the adrenal androgens, dehydroepiandrosterone (DHEA) and DHEA sulfate (Beckman Feuston, 2003). The rise in these hormones leads to the development of pubic and axillary hair. Recent evidence suggests... 

In the adrenal cortex, the outermost zona glomerulosa secretes the mineralocorticoid aldosterone, and corticosterone. The middle zona fasciculata and the inner zona reticularis secrete predominately the glucocorticoids cortisol and corticosterone. In the human, the inner zona reticularis secretes large amounts of the adrenal androgens, DHEA and DHEAS, as well as cortisol [12]. Whereas steroidogenesis in the... 

Other, more rare, forms of congenital adrenal hyperplasia are the result of deficiencies of other steroidogenic enzymes, particularlyl7-hydroxylase (P450cl7) and 11 (3-hydroxylase (Bondy, 1985 White and Speiser, 2000). As with P450c21 deficiency, impaired activity of either of these other enzymes also results in decreased cortisol production, enhanced ACTH secretion, and thus increased tropic drive to the adrenal. Deficiency of ll 3-hydroxylase is characterized by increased production of adrenal mineralocorticoids (e.g., corticosterone, aldosterone), resulting in sodium retention, potassium excretion, and increased blood pressure. In addition, adrenal androgens are produced in... 

Q2 The adrenal cortex secretes three main groups of hormones mineralocorticoid (e.g. aldosterone), glucocorticoids (e.g. cortisol, cortisone and corticosterone) and gonadocorticoids (mainly androgens with small amounts of progesterone and oestrogen). Aldosterone is a salt-retaining hormone which acts on the kidney to facilitate sodium and water reabsorption. 

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