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 (serum sodium less than 125 mmol/L) hyponatraemia, especially if they are symptomatic or show signs of hypovolaemia ¹.

Arrange an urgent 2-week wait referral if the hyponatraemia is asymptomatic but moderate (serum sodium 125–129 mmol/L) and 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 or signs of hypovolaemia ¹.