aldósteróni

Aldosterone is a steroid hormone that plays a crucial role in regulating blood pressure and electrolyte balance. It belongs to the mineralocorticoid class of hormones and is produced by the zona glomerulosa of the adrenal cortex, located on top of the kidneys. The primary function of aldosterone is to act on the kidneys, specifically on the distal tubules and collecting ducts.

In these kidney segments, aldosterone promotes the reabsorption of sodium ions (Na+) from the filtrate back into the bloodstream. Simultaneously, it stimulates the secretion of potassium ions (K+) and hydrogen ions (H+) from the blood into the filtrate, which are then excreted in urine. This action of sodium reabsorption is vital because water follows sodium osmotically. Therefore, by increasing sodium reabsorption, aldosterone leads to increased water reabsorption, which in turn expands the extracellular fluid volume and raises blood pressure.

The secretion of aldosterone is tightly regulated. The renin-angiotensin-aldosterone system (RAAS) is the main regulator. When blood pressure or blood flow to the kidneys decreases, the kidneys release renin, an enzyme. Renin initiates a cascade that ultimately leads to the production of angiotensin II, a potent vasoconstrictor that also stimulates aldosterone release from the adrenal cortex. High potassium levels in the blood can also directly stimulate aldosterone secretion. Conversely, low potassium levels and angiotensin II blockers can inhibit its release. Disorders involving aldosterone can lead to conditions like hyperaldosteronism, characterized by high blood pressure and low potassium levels, or hypoaldosteronism, resulting in low blood pressure and high potassium levels.