Primary polydipsia rare non-psychogenic causes. An example is polydipsia found in patients with autoimmune chronic hepatitis with severely elevated globulin levels. Evidence for the thirst being non-psychogenic is gained from the fact that it disappears after treatment of the underlying disease. Psychogenic polydipsia is also observed in some non-human patients, such as in rats. Primary polydipsia Primary polydipsia is a form of polydipsia characterised by excessive fluid intake in the absence of physiological stimuli to drink. This includes psychogenic polydipsia (PPD – not to be confused with postpartum depression), which is caused by psychiatric disorders, often schizophrenia, and often accompanied by the
Functional symptom Functional symptom A functional symptom is a medical symptom, with no known physical cause. It arises from a problem in the ‘functioning’ of the nervous system, and not due to a structural or pathologically defined disease. Functional symptoms are increasingly viewed within a framework in which psychological, physiological and biological factors should be considered to be relevant. Historically, there has often been fierce debate about whether certain problems are predominantly related to an abnormality of structure (disease) or function (abnormal nervous system functioning), and what are at one stage posited to be functional symptoms are sometimes later reclassified as organic,