Hyponatraemia: ignored or ignorance?
V Hundia, M Freeman & A Brueck
Background and objective
Hyponatraemia is a common metabolic disorder with a significant morbidity and mortality, especially in the elderly. However, its significance is often ignored, and when found, inadequately investigated and inappropriately managed. The objectives of this audit were to investigate the investigations and management of hyponatraemia in a large District General Hospital.
From the biochemistry database, all medical patients admitted during 2004 with plasma sodium of less than or equal to 130 mmols/L were identified. 90 patients were randomly selected and a notes review performed in 86 cases.
37 patients had plasma sodium less than or equal to 120 mmol/L. 46.5% were male and 53.5% female. 37 (43%) were aged 70 or less, while 49 (57%) were more than 70 years old. Postural blood pressure was measured in 9 patients (10%) 4 of whom had a postural drop. Renal function was checked in 100% of cases. Other blood investigations included: TSH (22%), FT4 (20%), plasma Glucose (45%), Cholesterol (12%), Triglycerides (3%) and Liver Function Test (74%), 9am cortisol (3%) and Short Synacthen Test in 2% of cases. Plasma and urine osmolalities were available in 23% and 19% of cases, of which 18.8% were paired samples. Urinary sodium was measured in 9% of cases. The most common underlying diagnoses (described in 25%) were diuretic use (10.5%) and SIADH (6.8%). A Management plan (33% of notes) mainly involved fluid restriction and stopping diuretics.
Although 58% patients were discharged, there was 42% mortality within 6 months.
This audit suggests that hyponatraemia is associated with significant morbidity and mortality. It is often inadequately investigated and inappropriately managed, a situation exacerbated by the lack of guidelines. It may hence be useful to have local or national guidelines which may help increase awareness regarding hyponatraemia and its management.