Dehydration is a common but potentially serious clinical condition caused by excessive loss of body water, with or without electrolyte imbalance. When the body loses more fluids than it takes in, normal physiological balance is disrupted. Blood volume drops, circulation becomes less efficient, and organs receive less oxygen and nutrients.
This condition is frequently seen in medical, pediatric, surgical, and geriatric care settings.
Epidemiology
- Dehydration occurs worldwide and is especially common in hot climates and low-resource environments.
- High-risk groups include infants, older adults, and critically ill patients.
- It is a significant cause of illness and hospital admissions.
Causes of Dehydration
- Gastrointestinal fluid loss: vomiting and diarrhea
- Excessive sweating: fever or prolonged heat exposure
- Renal fluid loss: diuretic medications and uncontrolled diabetes
- Inadequate fluid intake: reduced thirst sensation or altered mental state
Pathophysiology
- Fluid loss reduces circulating blood volume.
- Tissue perfusion decreases, affecting oxygen delivery.
- Electrolyte disturbances such as hypernatremia may develop.
- The body compensates through increased heart rate and peripheral vasoconstriction.
- Severe dehydration can progress to hypovolemic shock.
Classification
- Mild: 3–5% body weight loss with minimal symptoms
- Moderate: 6–9% body weight loss with clear signs of fluid depletion
- Severe: ≥10% body weight loss with unstable vital signs
Dehydration may also be categorized as:
- Isotonic dehydration
- Hypertonic dehydration
- Hypotonic dehydration
Clinical Features
- Thirst and dry mouth
- Dry mucous membranes
- Reduced skin elasticity
- Rapid heart rate
- Low blood pressure
- Reduced urine output
- Sunken eyes and lethargy in children
- Altered mental status in severe cases
Diagnostic Evaluation
- Clinical assessment of hydration status and vital signs
- Elevated hematocrit and serum sodium levels
- Increased blood urea nitrogen to creatinine ratio
- Concentrated urine with high specific gravity
Management
- Oral Rehydration Therapy (ORT): First-line for mild to moderate cases
- Intravenous fluids: Required for severe dehydration
- Treat underlying causes such as infections or endocrine disorders
- Monitor electrolytes and kidney function closely
Complications
- Hypovolemic shock
- Multi-organ dysfunction
- Acute kidney injury
- Electrolyte imbalance causing cardiac arrhythmias
- Increased mortality if untreated
Prevention
- Adequate daily fluid intake based on age and physiological needs
- Early use of oral rehydration solutions during diarrheal illness
- Replace fluids promptly during fever or heat exposure
- Close monitoring of high-risk patients in hospitals
