minéralocorticoid

Mineralocorticoid is a class of steroid hormones that play a crucial role in regulating the balance of water and salt in the body, primarily affecting the kidneys. The most prominent mineralocorticoid in humans is aldosterone. These hormones are synthesized in the adrenal cortex, a part of the adrenal glands located atop the kidneys.

The primary function of mineralocorticoids is to increase the reabsorption of sodium from the filtrate back into the bloodstream within the renal tubules. As sodium is reabsorbed, water follows it osmotically, leading to increased blood volume and blood pressure. Conversely, mineralocorticoids promote the excretion of potassium and hydrogen ions into the urine. This mechanism is vital for maintaining electrolyte balance and blood pressure homeostasis.

The secretion of aldosterone is tightly controlled by the renin-angiotensin-aldosterone system (RAAS) and by potassium levels in the blood. When blood pressure drops or sodium levels fall, the kidneys release renin, initiating a cascade that leads to aldosterone production. High potassium levels also directly stimulate aldosterone release. Imbalances in mineralocorticoid activity can lead to various health conditions. For example, excessive aldosterone can cause hypertension and hypokalemia (low potassium), while insufficient aldosterone can result in hypotension and hyperkalemia (high potassium), as seen in Addison's disease. Synthetic mineralocorticoids, like fludrocortisone, are used therapeutically to manage conditions characterized by mineralocorticoid deficiency.