What is the most prevalent mineralocorticoid that regulates fluid balance?

Aldosterone is the most prevalent mineralocorticoid responsible for regulating fluid and electrolyte balance in the body. It is produced by the adrenal cortex and plays a crucial role in maintaining blood pressure and the balance of sodium and potassium. By promoting sodium reabsorption in the kidneys, aldosterone helps to retain water, increasing blood volume and ultimately affecting blood pressure.

Cortisol, while also produced by the adrenal cortex and involved in many physiological processes, primarily functions as a glucocorticoid, mediating metabolism and immune response rather than fluid balance. Estrogen and progesterone are sex hormones primarily involved in reproductive system regulation and do not play a significant role in mineralocorticoid activity or fluid balance.