Which hormone is involved in water retention within the body?

Antidiuretic hormone (ADH), also known as vasopressin, plays a crucial role in regulating water balance within the body. It is produced in the hypothalamus and stored in the pituitary gland, from where it is released into the bloodstream. When the body experiences conditions of dehydration, increased blood osmolality, or low blood volume, ADH is secreted.

ADH acts primarily on the kidneys, promoting the reabsorption of water from the urine back into the bloodstream. This action helps to concentrate the urine, reduce water loss, and maintain blood volume and pressure. By doing so, ADH ensures that the body retains water and prevents excessive urination, effectively playing a central role in the body’s fluid balance.

In contrast, insulin primarily regulates glucose levels in the blood, epinephrine (adrenaline) is involved in the body's fight-or-flight response, and cortisol is a stress hormone that affects metabolism and immune responses. While these hormones have important functions in the body, they do not directly influence water retention in the way that ADH does.