What are the signs of dehydration?

Signs of Dehydration

Dry mucous membranes and skin tenting on clavicles (option D) are the most reliable clinical signs of dehydration. 1

Clinical Assessment of Dehydration

Dehydration assessment requires evaluating multiple clinical signs as no single sign is perfectly reliable. The most useful indicators include:

Physical Examination Findings

• Dry mucous membranes - A key sign of moderate dehydration (6-9% fluid deficit) 1
• Skin tenting/turgor loss - When pinched skin remains elevated ("tented") instead of quickly returning to normal position 1
• Sunken eyes - Another visual indicator of fluid deficit 1
• Dry tongue and furrowed tongue - Associated with moderate to severe volume depletion 1

Behavioral and Cognitive Signs

• Confusion and non-fluent speech - Important indicators of volume depletion, especially in older adults 1
• Extremity weakness - Another sign of moderate to severe dehydration 1
• Fatigue - May be reported by patients experiencing dehydration 2

Vital Sign Changes

• Tachycardia (elevated heart rate) - While option C mentions tachycardia (HR 110), this alone with normal blood pressure (130/74) is not specific for dehydration and could indicate many other conditions 1
• Postural pulse change - A rise of ≥30 beats per minute from lying to standing is highly sensitive (97%) and specific (98%) for significant volume depletion 1
• Severe postural dizziness - Inability to stand due to dizziness when changing position is another reliable indicator 1

Laboratory Findings and Their Interpretation

Laboratory values must be interpreted in clinical context:

• Urine specific gravity of 1.010 (option A) - This is actually within normal range (1.005-1.030) and suggests adequate hydration, not dehydration 1
• BUN 20, creatinine 2.0 (option B) - While elevated BUN:creatinine ratio can suggest dehydration, the presence of an S3 heart sound suggests volume overload or heart failure rather than dehydration 1
• Presence of S4 (option C) - This heart sound is associated with decreased ventricular compliance, not dehydration 1

Diagnostic Approach

A person with at least four of the following seven signs is likely to have moderate to severe volume depletion 1:

1. Confusion
2. Non-fluent speech
3. Extremity weakness
4. Dry mucous membranes
5. Dry tongue
6. Furrowed tongue
7. Sunken eyes

Common Pitfalls in Dehydration Assessment

• Relying on a single clinical sign rather than a constellation of findings 2
• Confusing dehydration with volume overload (as in option B with S3 gallop) 1
• Using urine specific gravity alone for diagnosis (as in option A) - this can be misleading 2
• Assuming tachycardia with normal blood pressure indicates dehydration (as in option C) - this is nonspecific 1
• Failing to recognize that dehydration assessment in older adults may be complicated by medications (like beta-blockers affecting heart rate response) 1

In conclusion, option D (dry mucous membranes, skin tenting on clavicles) represents the most reliable clinical indicators of dehydration among the choices presented.