Aldosterone
On Aldosterone
Aldosterone is a lesser-known hormone that plays a critical role in regulating sodium balance, blood volume, and blood pressure. This blog explores the discovery, function, and real-world importance of this essential steroid hormone.
The Discovery of Aldosterone
In the early 19th century, experiments involving the removal of the adrenal glands resulted in severe hyponatremia (low blood sodium) and hyperkalemia (high blood potassium), often leading to circulatory collapse. Cortisol was initially suspected to regulate mineral balance, but supplementation failed to restore normal sodium levels. This led researchers to conclude that the adrenal cortex must secrete an additional hormone (later termed a mineralocorticoid) with a primary role in electrolyte regulation.
In 1953, Simpson, Tait, and colleagues successfully isolated a previously unknown steroid hormone from adrenal cortex extracts. This hormone was far more potent than cortisol at promoting sodium retention. It was named aldosterone; aldo- referring to its unique aldehyde functional group, and -sterone reflecting its steroid structure.
What is Aldosterone important for?
Although it receives less attention than hormones like testosterone or estrogen, aldosterone is essential for maintaining homeostasis. It acts on the kidneys to increase sodium reabsorption and potassium excretion, which in turn regulates extracellular fluid volume, cardiac output, and blood pressure. Through this mechanism, aldosterone helps the body maintain adequate circulation and tissue perfusion, particularly during dehydration or blood loss.
Consequences of Elevated Aldosterone
Chronically elevated aldosterone levels are strongly associated with hypertension due to persistent sodium and water retention. Hypertension affects roughly one quarter of the global population and is closely linked to excessive dietary sodium intake. Over time, excessive aldosterone activity can contribute to cardiovascular strain and increased disease risk.
On the cover: the structure of aldosterone.
