Dehydration Risk Calculator

Assess dehydration severity using clinical signs, symptoms, and laboratory values. Essential tool for medical professionals.

Adult Patient
Pediatric Patient
Elderly Patient
Metric (kg, cm)
Imperial (lb, in)
Standard scale for clinical practice
For children with diarrhea (validated globally)
High sensitivity for pediatric dehydration

Patient Information

years
Patient age in years
kg
Current body weight in kilograms
kg
Previous body weight to calculate weight loss (more accurate than symptom-based assessment)

Clinical Signs and Symptoms

Select all applicable symptoms:

1 point
1 point
1 point
2 points
2 points
2 points
2 points
3 points

Vital Signs

bpm
mmHg
breaths/min

Ongoing Losses

Estimate ongoing fluid losses (optional, for more accurate fluid calculation):

mL/h
mL/h
mL/°C/day
Approximately 100-150 mL/°C/day extra loss
mL/h

Laboratory Values (Optional)

mg/dL
Blood Urea Nitrogen
mg/dL
mmol/L
For electrolyte-guided rehydration
g/mL
Normal range: 1.005-1.030
mL
Normal: >800 mL/day
Calculating...

Assessment History

Understanding Dehydration

Dehydration occurs when fluid losses exceed fluid intake, leading to a deficiency in total body water. It can range from mild to severe and can be life-threatening if not properly managed. Early recognition and appropriate treatment are crucial.

Clinical Importance: Dehydration is a common condition affecting all age groups, particularly children, the elderly, and athletes. It can lead to serious complications including electrolyte imbalances, renal failure, shock, and death if not properly managed.

Clinical Dehydration Scales

Common Dehydration Assessment Scales:
1. Clinical Dehydration Scale (CDS): 0-4 points = no dehydration, 5-8 points = mild, 9-12 points = moderate, 13-16 points = severe
2. WHO Dehydration Scale: For assessing dehydration in children with diarrhea
3. Gorelick Scale: Validated pediatric dehydration scale
4. DHAKA Score: For children with diarrhea in resource-limited settings
Scale Population Parameters Accuracy
Clinical Dehydration Scale (CDS) Children 1 month - 5 years General appearance, eyes, mucous membranes, tears Good for clinical practice
WHO Dehydration Scale Children with diarrhea General condition, eyes, thirst, skin pinch Well-validated globally
Gorelick Scale Children 1 month - 5 years Capillary refill, tears, mucous membranes, eyes High sensitivity
Adult Dehydration Assessment Adults Vital signs, urine output, laboratory values Clinical judgment based

Causes of Dehydration

Inadequate Intake
Reduced oral intake due to illness, impaired thirst, or limited access to fluids.
Excessive Losses
Gastrointestinal losses (vomiting, diarrhea), sweating, burns, or polyuria.
Medications
Diuretics, laxatives, certain antipsychotics, or chemotherapy agents.
Environmental Factors
Hot weather, high altitude, or intense physical activity without adequate hydration.
Medical Conditions
Diabetes (DKA, HHS), fever, sepsis, renal disease, or intestinal obstruction.
Special Populations
Infants, elderly, athletes, and individuals with chronic illnesses are at higher risk.

Signs and Symptoms by Severity

Severity Fluid Deficit Clinical Signs Management
Mild 3-5% of body weight Thirst, dry mouth, decreased urine output Oral rehydration
Moderate 6-9% of body weight Orthostatic hypotension, tachycardia, sunken eyes, poor skin turgor Oral/IV rehydration
Severe >10% of body weight Hypotension, tachycardia, altered mental status, anuria IV rehydration, hospital admission

Fluid Replacement Strategies

1

Oral Rehydration Therapy (ORT): For mild to moderate dehydration. Use oral rehydration solutions containing glucose and electrolytes. The WHO recommends a solution containing 75 mEq/L sodium, 20 mEq/L potassium, 65 mEq/L chloride, 10 mEq/L citrate, and 75 mmol/L glucose.

2

Intravenous Rehydration: For moderate to severe dehydration or when oral intake is not possible. Use isotonic solutions like normal saline or lactated Ringer's. Replace half of the deficit in the first 8 hours and the remainder over the next 16 hours.

3

Maintenance Fluids: Calculated using the 4-2-1 rule: 4 mL/kg for first 10 kg, 2 mL/kg for next 10 kg, 1 mL/kg for each additional kg. For example, a 70 kg adult needs 4×10 + 2×10 + 1×50 = 40+20+50 = 110 mL/h.

4

Special Considerations: Adjust fluid replacement based on ongoing losses, comorbidities (heart failure, renal disease), and electrolyte abnormalities. Monitor urine output, vital signs, and laboratory values during rehydration.

Clinical Note: Rapid correction of severe dehydration can lead to complications such as cerebral edema, particularly in children. Always monitor patients closely during rehydration and adjust the rate based on clinical response. In hyponatremic or hypernatremic dehydration, correct sodium abnormalities slowly to avoid complications.

Frequently Asked Questions

The most reliable clinical signs of dehydration include prolonged capillary refill time (>2 seconds), abnormal skin turgor (tenting), dry mucous membranes, sunken eyes, and decreased urine output. In infants, a sunken fontanelle is also a reliable sign. Laboratory findings such as elevated BUN:creatinine ratio (>20:1), elevated urine specific gravity (>1.030), and hypernatremia can confirm clinical suspicion.

Elderly patients are at higher risk due to decreased thirst sensation, reduced renal concentrating ability, medications (diuretics, laxatives), and comorbidities. Signs may be subtle or atypical, presenting as confusion, falls, or functional decline rather than classic symptoms. Laboratory values may show less pronounced changes due to age-related decreases in muscle mass affecting creatinine levels. Low-grade fever, tachycardia, or orthostatic hypotension may be the only indicators.

IV fluids should be used when oral rehydration is not possible due to persistent vomiting, altered mental status, or severe dehydration with hemodynamic instability. Other indications include ileus, intestinal obstruction, or severe malabsorption. In children, IV fluids are typically reserved for severe dehydration (>9% fluid deficit) or when oral rehydration has failed. For most cases of mild to moderate dehydration, oral rehydration is equally effective, safer, and less costly.

Fluid deficit is calculated based on estimated percentage of dehydration and body weight: Deficit (L) = % dehydration × body weight (kg). For example, a 10 kg child with 5% dehydration has a 0.5 L deficit (10 kg × 0.05 = 0.5 L). In clinical practice, dehydration is typically estimated as: mild = 3-5%, moderate = 6-9%, severe = >10%. If pre-illness weight is known, deficit = pre-illness weight - current weight. Remember to add maintenance fluids and ongoing losses to the deficit when calculating total fluid requirements.

Untreated dehydration can lead to serious complications including acute kidney injury, electrolyte imbalances (hyper/hyponatremia, hyperkalemia), metabolic acidosis, hypotension and shock, rhabdomyolysis, seizures (from electrolyte disturbances), venous thromboembolism (from hemoconcentration), and in severe cases, coma and death. Chronic mild dehydration may contribute to urinary tract infections, constipation, kidney stones, and impaired cognitive function in the elderly.