Abstract
<p>Background</p><p>Dehydration appears prevalent, costly and associated with adverse outcomes. We sought to generate consensus on such key issues and elucidate need for further scientific enquiry.</p> <p>Materials and methods:</p><p>A modified Delphi process combined expert opinion and evidence appraisal. Twelve relevant experts addressed dehydration’s definition, objective markers and impact on physiology and outcome.</p> <p>Results:</p><p>Fifteen consensus statements and seven research recommendations were generated. Key findings, evidenced in detail, were that there is no universally accepted definition for dehydration; hydration assessment is complex and requires combining physiological and laboratory variables; “dehydration” and “hypovolaemia” are incorrectly used interchangeably; abnormal hydration status includes relative and/or absolute abnormalities in body water and serum/plasma osmolality (pOsm); raised pOsm usually indicates dehydration; direct measurement of pOsm is the gold standard for determining dehydration; pOsm >300 and ≤280 mOsm/kg classifies a person as hyper or hypo-osmolar; outside extremes, signs of adult dehydration are subtle and unreliable; dehydration is common in hospitals and care homes and associated with poorer outcomes.</p> <p>Discussion:</p><p>Dehydration poses risk to public health. Dehydration is under-recognized and poorly managed in hospital and community-based care. Further research is required to improve assessment and management of dehydration and the authors have made recommendations to focus academic endeavours.</p> <p>•Key messages</p> <p>•Dehydration assessment is a major clinical challenge due to a complex, varying pathophysiology, non-specific clinical presentations and the lack of international consensus on definition and diagnosis.</p> <p>•Plasma osmolality represents a valuable, objective surrogate marker of hypertonic dehydration which is underutilized in clinical practice.</p> <p>•Dehydration is prevalent within the healthcare setting and in the community, and appears associated with increased morbidity and mortality.</p>