Signs of Dehydration in Nursing Home Residents

Abstract

Objectives: Although dehydration can affect mental and physical health, there is no clear, consistent, and reproducible diagnostic tool for this condition in older people. We applied multiple methods to detect dehydration with the aim of assessing the value of using urine analysis for this purpose.

Design: Nonrandomized cohort study.

Setting and participants: Sixty nursing home residents, aged 64-103 (mean 84) years.

Methods: Sampling of morning urine, blood analyses, and clinical examination. A previously validated algorithm summarized the urine specific gravity, osmolality, creatinine, and color to a Fluid Retention Index (FRI).

Results: The cut-off for renal fluid conservation consistent with dehydration (FRI ≥ 4.0) was reached by 51% of the cohort. No statistically significant linear correlation was found between FRI and serum osmolality (mean 307.5 mOsmol/kg) or plasma sodium (mean 139 mmol/L), but the subjects reported less thirst with increasing FRI scores (linear correlation r = -0.35; P < .03). Clinical examinations of mucous membranes and tongue furrows did not correlate with other markers of dehydration. Subjects with sunken eyes had higher C-reactive protein (P < .02) and lower albumin (P < .002) concentrations in plasma than the others, while impaired skin turgor only correlated with age (P < .04).

Conclusions/implications: Renal fluid conservation consistent with dehydration was found in half of the nursing home residents, which could partially be accounted for by decreased thirst. Clinical examinations probably reflected the physical status and age more than dehydration. The lack of correlation between the serum osmolality and the FRI, both of which are purported to be gold standards for dehydration, raises questions about whether a gold standard exists.

Keywords: Urine color; dehydration; frail elderly patients; urine osmolality.