Which hormone regulates water balance in the body?

Antidiuretic hormone (ADH), also known as vasopressin, plays a crucial role in regulating water balance in the body. It is produced in the hypothalamus and released from the posterior pituitary gland. When the body is dehydrated or when blood volume is low, ADH levels increase, promoting the reabsorption of water in the kidneys. This action reduces urine output and helps conserve water, thereby maintaining proper body hydration and blood pressure.

In contrast, aldosterone primarily affects sodium balance and therefore indirectly influences water balance by promoting sodium reabsorption; however, its direct mechanism is not primarily focused on water regulation. Cortisol, while essential for stress response and metabolism, does not have a primary role in water balance. Thyroid stimulating hormone (TSH) is involved in regulating thyroid hormones, which influence metabolic processes, but also do not directly control water balance. Therefore, the regulation of water balance specifically aligns with the function of ADH.