[1] It can also be caused by a change in the osmolality of the extracellular fluids of the body, hypokalemia, decreased blood volume (as occurs during major hemorrhage), and other conditions that create a water deficit.
[citation needed] Primary polydipsia describes excessive thirst and water intake caused in the absence of physiological stimuli to drink.
[4] Psychogenic polydipsia is an excessive water intake[1] seen in some patients with mental illnesses such as schizophrenia, or with developmental disabilities.
While many adult cases in the medical literature are associated with mental disorders, most patients with habit polydipsia have no other detectable disease.
The distinction is made during the water deprivation test, as some degree of urinary concentration above isosmolar is usually obtained before the patient becomes dehydrated."