Severe hyponatraemia - recognition and management

Hyponatraemia is the most common electrolyte disorder.In its severe form it has a high morbidity and mortality.The cause of the hyponatraemia must be identified by clinical assessment and investigations including serum and urinary sodium and osmolality.Determining if the patient is euvolaemic, hypovolaemic or hypervolaemic helps guide treatment.Most cases are caused by drugs, inappropriate secretion of antidiuretic hormone, and fluid retaining conditions such as heart failure.In addition to managing the underlying cause, severe hyponatraemia requires correction of the serum sodium.Treatment should be in an intensive care unit.Correcting the serum sodium too quickly risks causing cerebral demyelination which is frequently fatal.