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Hyperosmolar dehydration: a predictor of kidney injury and outcome in hospitalised older adults

El-Sharkawy, Ahmed M; Devonald, Mark A J; Humes, David J; Sahota, Opinder; Lobo, Dileep N.


Ahmed M El-Sharkawy

Mark A J Devonald

Clinical Associate Professor

Opinder Sahota

Professor of Gastrointestinal Surgery


© 2019 The Author(s) Background & aims: Hospitalised older adults are vulnerable to dehydration. However, the prevalence of hyperosmolar dehydration (HD) and its impact on outcome is unknown. Serum osmolality is not measured routinely but osmolarity, a validated alternative, can be calculated using routinely measured serum biochemistry. This study aimed to use calculated osmolarity to measure the prevalence of HD (serum osmolarity >300 mOsm/l) and assess its impact on acute kidney injury (AKI) and outcome in hospitalised older adults. Methods: This retrospective cohort study used data from a UK teaching hospital retrieved from the electronic database relating to all medical emergency admissions of patients aged ≥ 65 years admitted between 1st May 2011 and 31st October 2013. Using these data, Charlson comorbidity index (CCI), National Early Warning Score (NEWS), length of hospital stay (LOS) and mortality were determined. Osmolarity was calculated using the equation of Krahn and Khajuria. Results: A total of 6632 patients were identified; 27% had HD, 39% of whom had AKI. HD was associated with a median (Q1, Q3) LOS of 5 (1, 12) days compared with 3 (1, 9) days in the euhydrated group, P < 0.001. Adjusted Cox-regression analysis demonstrated that patients with HD were four-times more likely to develop AKI 12–24 h after admission [Hazards Ratio (95% Confidence Interval) 4.5 (3.5–5.6), P < 0.001], and had 60% greater 30-day mortality [1.6 (1.4–1.9), P < 0.001], compared with those who were euhydrated. Conclusion: HD is common in hospitalised older adults and is associated with increased LOS, risk of AKI and mortality. Further work is required to assess the validity of osmolality or osmolarity as an early predictor of AKI and the impact of HD on outcome prospectively.


El-Sharkawy, A. M., Devonald, M. A. J., Humes, D. J., Sahota, O., & Lobo, D. N. (2020). Hyperosmolar dehydration: a predictor of kidney injury and outcome in hospitalised older adults. Clinical Nutrition, 39(8), P2593-2599.

Journal Article Type Article
Acceptance Date Nov 14, 2019
Online Publication Date Nov 22, 2019
Publication Date Aug 1, 2020
Deposit Date Nov 20, 2019
Publicly Available Date Dec 4, 2019
Journal Clinical Nutrition
Print ISSN 0261-5614
Electronic ISSN 1532-1983
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 39
Issue 8
Pages P2593-2599
Keywords dehydration; hypohydration; older adults; osmolality; osmolarity; serum
Public URL
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