When should I consider referring a patient with hyponatraemia to secondary care?

Refer a patient with hyponatraemia to secondary care if they have acute onset (less than 48 hours) or severe hyponatraemia (serum sodium less than 125 mmol/L) and are symptomatic, or if they show signs of hypovolaemia ¹.

Arrange an urgent 2-week wait referral for asymptomatic, moderate hyponatraemia (serum sodium 125–129 mmol/L) if malignant disease is suspected as an underlying cause of SIADH ¹.

Refer if the cause of hyponatraemia is not clear, or if SIADH or other endocrine causes are suspected, as these require specialist input for diagnosis and treatment ¹.

Discuss with an endocrinologist about the need for admission or referral if the patient has hyponatraemia with moderate symptoms (serum sodium 125–129 mmol/L) ¹.

Consider urgent referral or admission if Addison's disease is suspected, or if reset osmostat syndrome or cerebral salt-wasting is suspected ¹.