Thirst and Dehydration

Medications such as diuretics, used to treat edema and high blood pressure, or excess laxative use can also increase salt and water loss and increase the risk of dehydration. Reduced thirst in response to a water deficit and reduced sensitivity of the kidneys to the water-retaining effect of vasopressin mean that the elderly are predisposed to dehydration. Despite the number of the thirst sensations centered on the mouth and throat, an area in the brain called the hypothalamus is the main control center for thirst. The hypothalamus also performs other important functions including regulation of certain hormones, reproduction, the thyroid and adrenal glands and growth, temperature, feeding and sleep/wake cycles. Reductions in blood volume may also affect thirst via the hormone angiotensin II. The environment can also influence our thirst and drinking through the ease or difficulty of obtaining drinks.