Definition of Psychogenic Polydipsia
Psychogenic polydipsia is excessive or abnormal thirst in the absence of a physiological stimulus to drink 4. Individuals with certain mental disorders may occasionally or regularly drink large amounts of water — up to 20 liters or more per day.
Synonyms for psychogenic polydipsia:
- Primary polydipsia
- Compulsive water drinking
- Self-induced water intoxication and psychosis
- Polydipsia with hyponatremia
- Psychosis-intermittent hyponatremia-polydipsia (PIP) syndrome.
Individuals with the following problems may develop psychogenic polydipsia 3:
- Schizophrenia (mainly during long-term hospital treatment)
- Mental retardation
- Kleine-Levin syndrome
- Anorexia nervosa
- Personality disorders
- Excessive beer drinking (beer potomania)
- Anxiety, especially in middle-aged women
- Emotional problems in children 4
Polydipsia is also a side effect of certain antipsychotics, such as phenothiazines 3.
The exact mechanism of psychogenic polydipsia is not clear; one possibility is the malfunction of the thirst center in the hypothalamus. Water overload can result in hyponatremia and therefore a drop of blood osmolality, which results in movement of water from the blood into the body cells, including the brain cells, which can cause brain swelling (cerebral edema).
Symptoms of Water Intoxication
Excessive drinking is associated with excessive urination (polyuria). Often no other symptoms are present, but when severe hyponatremia develops, symptoms of water intoxication may develop:
- Nausea, vomiting
- Irritability, restlessness
- Dysarthric speech
Symptomatic hyponatremia may occur when serum sodium levels drop under 130 meq/L (normal range 135-145 meq/L), which usually occurs only in those individuals with schizophrenia who take 3-4 liters of fluid acutely or 15-20 liters of fluid per day 3. Heavy smoking increases the risk of hyponatremia because nicotine stimulates ADH secretion and thus water retention 3.
- Inability to hold urine (enuresis)
- Bladder distension
- Kidney distension (hydronephrosis)
- Kidney failure
- Congestive heart failure
- Muscle disintegration (rhabdomyolysis) in severe hyponatremia
Other disorders with hyponatremia 2:
- Syndrome of Inappropriate ADH secretion (SIADH) caused by certain diuretics, meningitis, brain abscess, stroke (hypotonic hyponatremia)
- Diabetes insipidus (DI)
- Central or neurogenic DI, usually due to pituitary adenoma
- Nephrogenic DI due to certain kidney disorders
- Thiazide diuretics (hypovolemic hyponatremia)
- Adrenal insufficiency (Addison’s disease)
- Cerebral salt wasting caused by head injury, surgery, subarachnoid bleeding, stroke, brain tumors (hypovolemic hyponatremia)
- Pseudohyponatremia due to high blood protein or lipid levels, for example in multiple myeloma (isotonic hyponatremia)
- Chronic alcoholism
- Beer potomania
- Ecstasy use
- Excessive solute (hyperosmolar hyponatremia)
- Salt-wasting nephropathy
- Nephrotic syndrome
- Chronic heart failure
- Plasma osmolality <280 mOsm/kg
- Sodium normal or < 135 meq/L (hypotonic hypovolemic hyponatremia)
- 24-hour urine volume: increased
- Urine osmolality <100 mOsm/kg
- Sodium <20 meq/L
- Urea: normal
- Water deprivation test: urine osmolality greater than 750 mOsm/kg
Treatment may include 3:
- In the case of severe hyponatremia (Na <125 meq/L):
- Hypertonic 3% NaCl solution intravenously (the risk of neurological damage with rapid infusion)
- Furosemide to promote water excretion in hyponatremia.
- To cure polydipsia:
- Clozapine was helpful in patients with schizophrenia and polydipsia.
- Other drugs, such as olanzapine, risperidone, vasopressin receptor antagonists (conivaptan, tolvaptan), irbesartan, propranolol, acetazolamide and enalapril have been tested with various results.
- Behavioral therapy.