Signs of Dehydration
The key clinical signs of dehydration include sunken eyes, dry mucous membranes with a dry and coated tongue, tongue furrows, confusion, non-fluent speech, and weakness in limbs—with the presence of at least four of these seven signs indicating moderate to severe dehydration. 1
Primary Clinical Assessment
Physical examination findings that indicate dehydration include:
- Sunken eyes - a reliable indicator when combined with other signs 1
- Dry mucous membranes - particularly important in the oral cavity 1
- Dry tongue with white coating - an important clinical sign especially when combined with other findings 1
- Tongue with furrows - observed in moderate to severe dehydration 1
- Confusion or altered mental status - indicates significant fluid deficit 1
- Non-fluent speech - a neurological manifestation of dehydration 1
- Weakness in limbs - reflects systemic effects of volume depletion 1
Severity Grading
The diagnostic approach requires evaluating multiple signs together, as individual signs outside extremes are subtle and unreliable. 2 When a patient presents with at least four of the seven signs listed above (confusion, non-fluent speech, weakness in limbs, dry mucous membranes, dry tongue, furrowed tongue, and sunken eyes), this indicates moderate to severe dehydration requiring immediate intervention. 1
Additional Clinical Indicators in Specific Contexts
In patients with diarrheal illness, monitor for:
- Increased thirst - a subjective but important early warning sign 3
- Rapid breathing - may accompany severe dehydration 3
- Fever - can coexist with dehydration and worsen fluid losses 3
- Hypovolemic shock - manifested by tachycardia, hypotension, and altered perfusion 3
Laboratory Confirmation
While clinical signs guide initial assessment, plasma osmolality >300 mOsm/kg is the gold standard for confirming hypertonic dehydration. 1, 2 This objective measurement is underutilized in clinical practice but provides definitive diagnosis when clinical signs are equivocal. 2
Critical Pitfalls to Avoid
Do not rely on a single clinical sign to diagnose dehydration. The signs are non-specific when evaluated in isolation, and assessment requires a constellation of findings. 2 Additionally, signs of dehydration may be masked in hypernatremic patients, making diagnosis more challenging. 3
In elderly patients, dehydration presents atypically and progresses more rapidly. 4 This population requires heightened vigilance as they are at higher risk for complications and may not exhibit classic signs until dehydration is advanced. 4
Recognize that "dehydration" and "hypovolemia" are distinct entities that are incorrectly used interchangeably. 2 Dehydration specifically refers to water loss from the intracellular compartment with hypernatremia, while hypovolemia refers to extracellular volume depletion that can occur with varying sodium states. 2, 5