Psychogenic polydipsia

Commonly encountered in patients with psychiatric disorders.

Presents with water-seeking and excessive drinking, sometimes accompanied by hyponatraemia and water intoxication.

Neuropsychiatric manifestations of hyponatraemia include headache, nausea, cramping, hyporeflexia, dysarthric speech, lethargy, confusion, seizures, and delirium. Coma and even sudden death can ensue as sodium status worsens.

Complications of psychogenic polydipsia include incontinence and enuresis, bladder dilation and hydronephrosis, renal and congestive heart failure, and osteoporosis and associated pathological fractures.

Diagnosis is one of exclusion. Other medical causes of polydipsia, polyuria, and/or hyponatraemia need to be ruled out.

Management includes fluid restriction and behavioural and pharmacological therapy. Serum sodium should be monitored vigilantly and frequently with judicious use of hypertonic saline to treat symptomatic or severe hyponatraemia.

Polydipsia is excessive or abnormal thirst, accompanied by intake of excessive quantities of water or fluid. Psychogenic polydipsia (PPD), or primary polydipsia, is characterised by excessive volitional water intake and is often seen in patients with severe mental illness and/or developmental disability. There may be no physical effects, but hyponatraemia can occur.