What hormone is responsible for increasing sodium reabsorption in the kidneys?

Aldosterone is a steroid hormone produced by the adrenal glands that plays a critical role in regulating sodium and potassium levels in the body. Its primary function is to increase sodium reabsorption in the kidneys, particularly in the distal tubules and collecting ducts. By promoting sodium reabsorption, aldosterone facilitates water retention, which helps to maintain blood volume and blood pressure.

When aldosterone levels are elevated, the kidneys reabsorb more sodium back into the bloodstream instead of excreting it in urine. This process is crucial for maintaining electrolyte balance and normal cardiovascular function. Additionally, as sodium is reabsorbed, water follows osmotically, leading to an increase in fluid volume.

Understanding the function of aldosterone is essential for comprehending how the body regulates its fluid and electrolyte balance, particularly under conditions of stress or dehydration.