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Aldosterone synthase, also called steroid 18-hydroxylase, corticosterone 18-monooxygenase or P450C18, is a steroid hydroxylase cytochrome P450 enzyme involved in the biosynthesis of the mineralocorticoid aldosterone and other steroids. The enzyme catalyzes sequential hydroxylations of the steroid angular methyl group at C18 after initial 11β ...
Aldosterone causes the tubules of the kidneys to retain sodium and water. This increases the volume of fluid in the body and drives up blood pressure. [citation needed] Steroid hormones are synthesized from cholesterol within the adrenal cortex. Aldosterone and corticosterone share the first part of their
Aldosterone stimulates Na + and water reabsorption from the gut, salivary and sweat glands in exchange for K +. Aldosterone stimulates secretion of H + via the H+/ATPase in the intercalated cells of the cortical collecting tubules; Aldosterone upregulates expression of NCC in the distal convoluted tubule chronically and its activity acutely. [18]
18-Hydroxylase (aldosterone synthase) – mineralocorticoid synthesis; 21-Hydroxylase – corticosteroid synthesis; Cytochrome P450 (CYP1, 2, 3) – estrogen metabolism; Hydroxysteroid dehydrogenases (and ketosteroid reductases) 3α-Hydroxysteroid dehydrogenase – androgen, progestogen, and neurosteroid synthesis and metabolism
In humans and other animals, the adrenocortical hormones are hormones produced by the adrenal cortex, the outer region of the adrenal gland.These polycyclic steroid hormones have a variety of roles that are crucial for the body's response to stress (for example, the fight-or-flight response), and they also regulate other functions in the body.
The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2).
Measuring aldosterone alone is not considered adequate to diagnose primary hyperaldosteronism. Rather, both renin and aldosterone are measured, and a resultant aldosterone-to-renin ratio (ARR) is used for case detection. [20] [21] A high aldosterone-to-renin ratio suggests the presence of primary hyperaldosteronism. The diagnosis is made by ...
Secondary hyperaldosteronism (also hyperreninism, or hyperreninemic hyperaldosteronism) is due to overactivity of the renin–angiotensin–aldosterone system (RAAS).. The causes of secondary hyperaldosteronism are accessory renal veins, fibromuscular dysplasia, reninoma, renal tubular acidosis, nutcracker syndrome, ectopic tumors, massive ascites, left ventricular failure, and cor pulmonale.