Psychogenic polydipsia is a condition in which patients have an uncontrollable urge to drink excess 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 relies on restricting the affected patient’s intake of liquids. It is important to differentiate the condition from other diseases that can mimic it, as the treatments may vary.
Patients affected by psychogenic polydipsia typically 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 thought to stem from the neurochemical imbalances associated with their underlying psychiatric conditions. Patients with the condition typically drink over 2.6 gallons (10 liters) of fluid a day.
The symptoms of psychogenic polydipsia can vary. Often patients try to hide the fact that they are drinking so much fluid, so other people around them might not notice that they are taking in so much water. If the condition goes on for an extended period, 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 eliciting a detailed history, determining whether there are underlying psychiatric disorders, learning what medications the patient is on, and performing laboratory tests. Patients with the condition often develop low levels of sodium in the blood. They also produce copious 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 increases after forbidding patients from drinking, the diagnosis can be confirmed.
It is important to differentiate psychogenic polydipsia from other medical conditions that can cause similar laboratory abnormalities. The syndrome of inappropriate secretion of anti-diuretic hormone (SIADH) can also cause a patient to develop low levels of sodium in the blood. In this condition, however, there is typically a higher amount of sodium in the urine, and the hyponatremia does not typically resolve immediately on restriction access to fluids. Other conditions that can mimic psychogenic polydipsia include ecstasy intoxication, pseudohyponatremia, and exercise-associated hyponatremia.