Which hormone is secreted by the anterior pituitary and influences water retention in the kidneys?

The hormone that influences water retention in the kidneys and is secreted by the anterior pituitary is vasopressin, which is also known as antidiuretic hormone (ADH). Vasopressin plays a crucial role in regulating the body's water balance by promoting the reabsorption of water in the kidneys' collecting ducts. This action decreases urine output and helps maintain fluid homeostasis.

Although vasopressin and antidiuretic hormone refer to the same molecule, the anterior pituitary primarily secretes vasopressin in response to signals indicating dehydration or increased plasma osmolality. This makes it important for the management of water retention.

Other hormones, like aldosterone, are involved in fluid and electrolyte balance but are secreted by the adrenal glands, not the anterior pituitary. Thyroid hormones, on the other hand, play a significant role in metabolism but do not directly influence water retention in the kidneys. Thus, the correct association with the anterior pituitary and its effect on kidney function in terms of water retention is indeed vasopressin.