Psychogenic polydipsia is a condition in which patients have an uncontrollable urge to drink excessive amounts of water. The term polydipsia refers to drinking too much water, and the term psychogenic refers to the fact that the desire to drink water stems from a mental disorder. Symptoms include increased thirst, increased urination, nausea, vomiting, confusion, and seizures. Treatment of the condition is based on restricting the fluid intake of the affected patient. It is important to differentiate the condition from other diseases that can mimic it, as treatments may vary.
Patients affected by psychogenic polydipsia often have other coexisting psychiatric conditions, such as schizophrenia, bipolar disorder, or depression. The reason why patients affected by the disorder develop insatiable thirst is not well understood, but is believed to stem from neurochemical imbalances associated with their underlying psychiatric conditions. Patients with the condition typically drink more than 2.6 gallons (10 liters) of fluid per day.
The symptoms of psychogenic polydipsia can vary. Patients often try to hide the fact that they are drinking a lot of fluids, so others around them might not realize that they are drinking that much water. If the condition continues for a long period of time, patients can develop a condition called hyponatremia, which is an electrolyte imbalance in which the concentration of sodium in the blood is too low. Symptoms of this can include nausea, vomiting, headache, confusion, or even seizures. Other symptoms of psychogenic polydipsia include increased urination and psychiatric symptoms.
The process of diagnosing a patient with psychogenic polydipsia includes taking a detailed history, determining if there are underlying psychiatric disorders, learning what medications the patient is taking, and performing laboratory tests. Patients with the condition often develop low sodium levels in their blood. They also produce large amounts of dilute urine. The diagnosis is confirmed by doing a monitored water restriction test, in which patients are prohibited from drinking anything. If the concentration of sodium in the blood rises after forbidding patients to drink, the diagnosis can be confirmed.
It is important to differentiate psychogenic polydipsia from other medical conditions that can cause similar laboratory abnormalities. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) can also cause a patient to develop low blood sodium levels. In this condition, however, there is usually an increased amount of sodium in the urine, and the hyponatremia does not usually resolve immediately by restricting access to fluids. Other conditions that can mimic psychogenic polydipsia include ecstasy intoxication, pseudohyponatremia, and exercise-associated hyponatremia.