Efficacy of Current Management of Hyponatraemia in Hospitalised Patients: Results from an Observational Study in a UK Teaching Hospital

Presentation Number: SUN-0455
Date of Presentation: June 22nd, 2014

Ploutarchos Tzoulis*1 and Pierre-Marc Gilles Bouloux2
1Royal Free Hospital, London, United Kingdom, 2UCL Medical School, London, United Kingdom


Introduction: Hyponatraemia is the most common electrolyte disorder encountered in hospitalised patients. There is paucity of data about the efficacy of current management of hyponatraemia in hospitalised patients in a real-life clinical setting.

Methods: This observational study was conducted in a large teaching hospital in London and included all adult inpatients with serum sodium (sNa) ≤ 128 mmol/l at any point during hospitalisation over a 3-month period (1st March 2013 – 31st May 2013). A retrospective case notes review was conducted with the aim of evaluating the effect of the current management of hyponatraemia on correction of sNa. All variables were analysed as median (interquartile range; IR) values.

Results:139 patients (69 males, 70 females) aged 74 (59-82) years developed sNa ≤ 128 mmol/l over the study period. The aetiology of hyponatraemia was recorded only in 58 cases (41.7%) with 25 patients being classified as having hypovolaemic hyponatraemia, 21 as SIADH and 12 as hypervolaemic hyponatraemia. The admission sNa was 130 (126-134) mmol/l, the nadir sNa during hospitalisation was 125 (122-127) mmol/l and sNa on discharge 132 (128-136) mmol/l. The in-hospital mortality rate was 17.3% and median length of hospital stay was 12 days. 

At 24 hours after development of sNa ≤ 128 mmol/l, sNa concentration was measured in 78.4% of patients with a change in sNa levels of +2 (0 to +4.5) mmol/l. A decrease in sNa levels was recorded in 20.2% of patients, while 8.2% of patients had sNa corrected by > 8 mmol/l, either due to treatment with normal saline in 2/3 of cases or due to haemodialysis in 1/3 of cases.

At 48 hours after development of sNa ≤ 128 mmol/l, sNa was measured in 77.7% of patients with a change of +3 (0 to +6) mmol/l. Reduction in sNa was recorded in 22.2% of cases with no cases of correction by > 18 mmol/l. Among hypovolaemic patients, the 48-hour change in sNa was +3 (0 to +8) mmol/l with reduction of sNa in 16% of cases. Among patients with SIADH, the 48-hour change was +1 (-1.5 to +5) mmol/l with reduction in sNa levels in 33.3% of cases.

With regards to sNa levels ≥ 132 mmol/l, 69.8% of patients reached this target with required time being 3 (2-6) days. Among hypovolaemic patients, the time period needed to reach sNa threshold of 132 mmol/l was 3 (1.5 - 5) days with an estimated rate of sNa change of 3 (1 –7.5) mmol/l/day. Among patients with SIADH, the required time to reach the cut-off of 132 mmol/l was 6.5 (3-10) days with an estimated rate of sNa change of 1.2 (1 - 2.5) mmol/l/day.

Discussion: This study demonstrated a slow rate of correction of sNa, especially in SIADH, with one third of patients with SIADH having further reduction in sNa concentration during the first 48 hours. Hyponatraemia was frequently undertreated, especially in cases of SIADH. Therefore, this study highlights the need for more intensive management of hospitalised patients with hyponatraemia.


Nothing to Disclose: PT, PMGB