Water is essential for the normal flow of metabolic processes in the body. It constantly leaves our body while we breathe, when we sweat, and with urine, so we experience thirst to replenish the amount of water required for the functioning of our body. We feel thirsty thanks to special areas in the brain that, when excited, make us want to drink any fluid – juice, water, or tea. The activation of these brain areas may happen due to different causes, including certain pathologic processes in the brain. But most often the activation happens when specific receptors send signals to the brain informing it that the composition of blood has changed (due to intensive physical activity, for example) and it should be corrected by drinking water. However, excessive thirst that does not go away can be a sign of some serious disorders, such type of thirst is called polydipsia.
Healthy thirst differs from polydipsia in that it is easier to quench it. In polydipsia, even if a person drinks a lot of water, the thirst returns quite soon. For healthy individuals it is enough to consume about 15.5 cups (3.7 liters) of fluids per day for men and 11.5 cups (2.7 liters) of fluids per day for women. But patients with polydipsia may drink up to 63.5 cups (15 liters) or 84.5 cups (20 liters) per day. Excessive drinking usually goes hand in hand with polyuria, an abnormally large production of urine.
Polydipsia is one of the most common symptoms of uncontrolled diabetes mellitus. Insulin assists glucose in entering the cells of the body to be used for energy purposes. In this type of diabetes, high glucose levels in the blood draw the water out of the cells. The water leaves the body through kidneys which causes dehydration and increased thirst. Excessive thirst is also the leading symptom of another type of diabetes – diabetes insipidus. This condition is characterized by inadequate production of the hormone called vasopressin that can be associated with the damage of the pituitary gland or hypothalamus. Low production of vasopressin can be genetic as well. Vasopressin deficiency causes increased urination, dehydration and severe thirst.
Treatment of polydipsia
Sometimes a temporary period of extreme thirst can be mistaken for polydipsia. It is worth seeing a doctor if excessive thirst lasts for more than a few days and does not change perceivably based on the amount of water one drinks or the levels of physical activity.
It is contraindicated to limit the consumption of fluids in polydipsia; certain measures should be taken to eliminate the results of disturbed water-electrolyte metabolism. Polydipsia treatment is aimed at the therapy of the underlying disease that has caused excessive thirst. When the main disease is successfully taken under control, the intensity of thirst usually goes back to normal.
Thus, if excessive thirst is associated with type 1 diabetes, it is relieved when diabetes is taken under control with regular injections of insulin, and in type 2 diabetes, it is controlled when high blood sugar levels are lowered. If polydipsia is a sign of diabetes insipidus, it goes away when vasopressin hormone replacement therapy is started.
Complications of polydipsia
When progressing rapidly and acutely, polydipsia may provoke the development of water-electrolyte disorders. When developing in the background of undiagnosed diabetes, thus being the symptom of diabetes, excessive thirst can be dangerous – prolonged dehydration leads to headaches, dizziness, nausea and fainting. Such dehydration may potentially provoke diabetic ketoacidosis subsequently leading to failure of the body organs, coma or death.