Evaluation and Treatment of Dehydration

Assessment of Dehydration

The degree of dehydration should be determined through careful physical examination, with mild dehydration (3-5% fluid deficit) characterized by increased thirst and slightly dry mucous membranes, moderate dehydration (6-9% fluid deficit) characterized by loss of skin turgor and dry mucous membranes, and severe dehydration (≥10% fluid deficit) characterized by severe lethargy or altered consciousness and prolonged skin tenting 1, 2
Rapid, deep breathing, prolonged skin retraction time, and decreased perfusion are more reliable indicators of dehydration than sunken fontanelle or absence of tears, according to the Centers for Disease Control and Prevention (CDC) 1
Capillary refill time correlates with fluid deficit, though fever, ambient temperature, and age can affect this measurement, as reported by the CDC 1

The American Academy of Pediatrics recommends treatment based on the degree of dehydration, with mild dehydration (3-5% fluid deficit) treated with oral rehydration solution (ORS) containing 50-90 mEq/L of sodium, administered at 50 mL/kg over 2-4 hours 3, 2
For moderate dehydration (6-9% fluid deficit), the World Health Organization (WHO) recommends using the same ORS administration procedure as for mild dehydration, with an increased fluid amount of 100 mL/kg over 2-4 hours 3, 2
Severe dehydration (≥10% fluid deficit) constitutes a medical emergency requiring immediate IV rehydration with boluses of Ringer's lactate solution or normal saline, as recommended by the WHO 3, 2

The CDC recommends that breast-fed infants continue nursing on demand, while bottle-fed infants should use full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration 4, 5
For adults and children over 4-6 months, feeding should begin as soon as appetite returns, and "resting the bowel" through fasting should be avoided, according to the WHO 6
Soft drinks are not recommended for rehydration due to their high osmolality, and anti-diarrheal agents are contraindicated for the treatment of diarrheal disease, as reported by the CDC 6

The induced change in serum osmolality should not exceed 3 mOsm/kg/h during fluid replacement, and fluid replacement should correct estimated deficits within the first 24 hours, according to the American Diabetes Association 7
Successful progress is judged by hemodynamic monitoring, measurement of fluid input/output, and clinical examination, with reassessment of hydration status after 2-4 hours 7
In patients with renal or cardiac compromise, monitoring of serum osmolality and frequent assessment of cardiac, renal, and mental status must be performed during fluid resuscitation to avoid iatrogenic fluid overload 7

The American Academy of Pediatrics and the Infectious Diseases Society of America recommend reduced osmolarity oral rehydration solution (ORS) as the first-line treatment for mild to moderate dehydration in all age groups, regardless of the underlying cause 8, 9

For severe dehydration, the American College of Emergency Physicians and the Infectious Diseases Society of America recommend immediate intravenous rehydration with isotonic fluids (lactated Ringer's or normal saline) 8, 9
The Infectious Diseases Society of America guidelines suggest administering 20 mL/kg IV boluses until pulse, perfusion, and mental status normalize 9
Once stabilized, transition to ORS for remaining deficit replacement, as recommended by the World Health Organization and the Infectious Diseases Society of America 9, 10

The World Health Organization and the Infectious Diseases Society of America recommend using commercially available reduced osmolarity ORS (total osmolarity <250 mmol/L) containing 50-90 mEq/L of sodium 8, 11, 10
Acceptable products include Pedialyte, CeraLyte, and Enfalyte/Infalyte, as suggested by the American Academy of Pediatrics and the Infectious Diseases Society of America 11

The American Academy of Pediatrics and the Infectious Diseases Society of America recommend resuming age-appropriate normal diet during or immediately after rehydration is complete 8, 9, 10
Breastfed infants must continue nursing throughout the illness, as emphasized by the World Health Organization and the Infectious Diseases Society of America 8, 9, 11

Switch to intravenous rehydration if severe dehydration, shock, or altered mental status present, as recommended by the American College of Emergency Physicians and the Infectious Diseases Society of America 8, 9
The Infectious Diseases Society of America guidelines also recommend switching to intravenous rehydration if paralytic ileus develops, patient cannot tolerate oral/nasogastric intake, or ORS therapy fails 8, 9, 11, 10

A meta-analysis of 17 RCTs involving 1,811 pediatric patients demonstrated no clinically important differences between ORS and IV therapy in rehydration success, weight gain, electrolyte abnormalities, or diarrhea duration, supporting ORS as the safer first-line approach 11, 10