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. 2018 Dec 6;18(1):93.
doi: 10.1186/s12902-018-0320-9.

Investigation and management of moderate to severe inpatient hyponatraemia in an Australian tertiary hospital

Kathryn Berkman  1 , Kate Haigh  1 , Ling Li  1 , Jack Lockett  1   2 , Goce Dimeski  3   2 , Anthony Russell  1   2 , Warrick J Inder  4   5
Affiliations

Investigation and management of moderate to severe inpatient hyponatraemia in an Australian tertiary hospital

Kathryn Berkman et al. BMC Endocr Disord. .

Abstract

Background: Hyponatraemia is the most common electrolyte disturbance amongst hospitalised patients. Both American and European guidelines recommend fluid restriction as first line treatment for SIADH, however differ on second line recommendations. The objective of this study was to examine investigation and management of hyponatraemia in hospitalised patients in an Australian tertiary hospital.

Methods: A retrospective audit was conducted of electronic medical records and laboratory data of inpatients with serum sodium (Na) ≤125 mmol/L, admitted over a 3 month period to the Princess Alexandra Hospital, Brisbane, Australia. The main outcomes measured included: demographic characteristics, investigations, accuracy of diagnosis, management strategy, change in Na and patient outcomes.

Results: The working clinical diagnosis was considered accurate in only 37.5% of cases. Urine Na and osmolality were requested in 72 of 152 patients (47.4%) and in 43 of 70 euvolaemic patients (61.4%). Thyroid function tests (67.1%) and morning cortisol (45.7%) were underutilized in the euvolaemic group. In the SIADH cohort, fluid restriction resulted in a median (IQR) 7.5 mmol/L (4-10.5) increase in Na after 3 days; no treatment resulted in a median 0 mmol/L (- 0.5-1.5) change. Oral urea was utilized in 5 SIADH patients where Na failed to increase with fluid restriction alone. This resulted in a median 10.5 mmol/L (3.5-13) increase in Na from baseline to day 3. There were no cases of osmotic demyelination. The median length of stay was 8 days (4-18.5). Mortality was 11.2% (17 patients). There was a weak but significant correlation between nadir serum Na and mortality (R = 0.18, P = 0.031).

Conclusion: Inpatient hyponatraemia is often inadequately investigated, causing errors in diagnosis. Treatment is heterogeneous and often incorrect. In cases with hyponatraemia refractory to fluid restriction, oral urea presents an effective alternative treatment.

Keywords: Fluid restriction; Hyponatraemia; SIADH; Urea.

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Conflict of interest statement

Ethics approval and consent to participate

Ethics approval was obtained from the Metro South Human Research Ethics Committee (reference HREC/16/QPAH/490). All necessary permissions to access medical records from the Princess Alexandra Hospital were obtained. Consent to participate was not a requirement.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Working diagnosis by treating team and retrospective adjudicated diagnosis after review
Fig. 2
Fig. 2
Median change in serum sodium (Δ Na) in adjudicated SIADH group between 0 and 72 h
See this image and copyright information in PMC

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