Primary polydipsia Alcoholism may cause physiological thirst since ethanol inhibits vasopressin, the hormone primarily responsible for water retention in osmoregulation. The following conditions should also be excluded: DI, cerebral salt wasting, pseudohyponatraemia caused by hyperlipidemia or hyperparaproteinemia, SIADH, mineralcorticoid deficiency, salt-wasting nephropathy, nephrotic syndrome, chronic heart failure and cirrhosis. Tobacco smoking is an often overlooked factor linked to hyponatremia, due to the ADH-releasing effect of nicotine, although this is usually limited to heavy smokers. One study suggested that around 70% of patients with self-induced polydipsia were tobacco smokers. Diagnostic tests for primary polydipsia usually involves the fluid deprivation test to exclude ADH
Primary polydipsia be found among others in the absence of psychosis, although there is no existent research to document this other than anecdotal observations. Such persons typically prefer to possess bottled water that is ice-cold, consume water and other fluids at excessive levels. However, a preference for ice-cold water is also seen in diabetes insipidus. Psychogenic polydipsia individuals with schizophrenia is associated with differences seen in neuroimaging. MRI scans may be used to help with differentiating between PPD and diabetes insipidus, such as by examining the signal of the posterior pituitary (weakened or absent in "central" DI). Some patients, most often with