MON-133 Hyponatremia in Hospital Care

Abstract

Hyponatremia (serum sodium <136 mmol/L) is associated with significant morbidity and mortality. International guidelines suggest a clear algorithm for investigation, inclusive of measurements of paired urine sodium and osmolality, TFTs and a morning cortisol. The aim of this study was to prospectively investigate the assessment, management and clinical outcomes associated with hyponataemia in hospital admissions. Methods:This prospective study was conducted from Sept 9, 2018-Oct 3,2018. All admissions through the MAU were included excepting surgery & oncology and admissions in the prior 3 months. Follow-up data was collected in the six months post admission. Information on all hyponatremic admissions was through combined review of patient charts and hospital laboratory database. Results: 418 patients in total were admitted, of whom 75 (18%, 35 male, 40 female) had measurable hyponatremia. Mean age was 74 (SD=14). 63 patients (84%) had mild hyponatremia (130-135mmol/L), 9 (12%) had moderate hyponatremia (125-129mmol/L) and 3 (4%) had severe (<125 mmol/L) hyponatraemia on admission. 4 (5%) patients only had measurements of paired serum and urine osmolality & sodium, 19 (25%) had TFTs measured, and 1 (1%) had an early morning cortisol. Only 9 (12%) were assessed by a consultant endocrinologist. 47 (63%) were taking a culprit medication (known to cause hyponatremia) on admission, and 15 patients/47 (32%) had the presumed causal medication discontinued. This resulted in an average rise in serum sodium of 4.7mmol/L by discharge. Mean length of hospital stay was 7 days for mild, 9 days for moderate and 16 days for severe hyponatremia cases, and 2 patients died in-hospital. Of the 73 surviving patients, 23 (31%) did not have a sodium remeasured at discharge and 27 (37%) were discharged with persistent hyponatraemia. 20 patients (27%) were re-admitted in the following 6 months. Over the same time period, 12/73 (16%) of hyponatraemic patient admissions died, compared to 13 /332 (4%) of normo-natraemic admissions,which was statistically significant χ²(1, N = 405) = 16.2, p < 0.01. Conclusions:Hyponatraemia was a highly prevalent condition on admission accounting for 18% of all admissions, which was under investigated and underestimated. Endocrine evaluation was underutilised. Hyponatraemia was associated with a longer length of stay, and a four-fold excess in mortality in the six months post-discharge. These findings emphasise the need for formal assessment and treatment along a dedicated protocol for all patients and we have proposed a ‘hospital alert’ system be installed for automatic consultation.