Calculating Maintenance Oral Liquid (MOL) in Pediatric Nephrotic Syndrome
Use the Holliday-Segar formula to calculate maintenance fluid requirements: 100 ml/kg/day for the first 10 kg, plus 50 ml/kg/day for the next 10 kg (10-20 kg), plus 20 ml/kg/day for each kg above 20 kg. 1, 2, 3
Step-by-Step Calculation Method
Basic Formula Application
For hourly rates, convert the daily calculation as follows: 3
- 4 ml/kg/hour for the first 10 kg
- 2 ml/kg/hour for the next 10 kg (10-20 kg)
- 1 ml/kg/hour for each kg above 20 kg
This formula is based on the principle that water requirements parallel energy needs at approximately 1 kcal per 1 ml of water 2
Critical Modification for Nephrotic Syndrome
In children with nephrotic syndrome, oral fluid intake should be concentrated and restricted to avoid marked edema, rather than following standard maintenance calculations. 1
- Avoid intravenous fluids and saline whenever possible in nephrotic syndrome management 1
- Fluid restriction is particularly important because nephrotic children have impaired sodium excretion due to direct activation of epithelial sodium channels (ENaC) by urinary proteases, independent of aldosterone 1
Fluid Management Algorithm for Nephrotic Syndrome
Initial Assessment
- Calculate baseline maintenance needs using Holliday-Segar formula 1, 2, 3
- Restrict calculated volume to 65-80% of standard maintenance in acutely ill nephrotic children at risk of increased ADH secretion 2, 3
- Further restrict to 50-60% of calculated volume if the child has concurrent heart failure, renal failure, or hepatic failure 2, 3
Clinical Indicators for Fluid Administration
Only provide IV fluids or albumin infusions based on clinical indicators of hypovolemia, including: 1
- Oliguria
- Acute kidney injury
- Prolonged capillary refill time
- Tachycardia
- Hypotension
- Abdominal discomfort
- Failure to thrive
Do NOT administer fluids based solely on serum albumin levels 1
Fluid Type Selection
If IV fluids are necessary, use isotonic fluids (0.9% saline or balanced crystalloids) for the first 24 hours in acutely ill children. 1, 2, 3
- Balanced/buffered crystalloids are preferred over 0.9% saline for initial resuscitation 2
- Chloride intake should be slightly lower than the sum of sodium and potassium intakes (Na + K - Cl = 1-2 mmol/kg/day) to avoid iatrogenic metabolic acidosis 1, 3
Daily Monitoring Requirements
Total Fluid Accounting
Include ALL fluid sources in daily calculations: 2, 3
- IV fluids
- Blood products
- IV medications
- Arterial/venous line flushes
- Enteral intake (oral liquids)
This comprehensive accounting prevents "fluid creep" and fluid overload 2
Clinical Monitoring
- Perform daily urine intake/output (I/O) charting until optimal results are obtained 4
- Reassess fluid balance and clinical status at least daily 2, 3
- Monitor serum electrolytes regularly, especially sodium 2, 3
- Assess for signs of fluid overload (>10% increase in cumulative fluid balance from baseline), which independently predicts increased morbidity and mortality 2
Common Pitfalls to Avoid
Critical Errors in Nephrotic Syndrome
- Never use standard maintenance fluid volumes without restriction in nephrotic children with active edema 1
- Avoid routine albumin infusions based solely on laboratory values rather than clinical hypovolemia 1
- Do not use hypotonic fluids in acutely ill children, as they significantly increase the risk of hospital-acquired hyponatremia and potentially fatal hyponatremic encephalopathy 2
Special Considerations
Individual patient needs may deviate markedly from standard calculations depending on: 1, 2, 3
- Degree of edema and fluid retention
- Presence of dehydration
- Excessive water losses (fever, hyperventilation)
- Renal concentrating ability
- Concurrent medications (especially diuretics)
Water requirements increase with fever, hyperventilation, hypermetabolism, and gastrointestinal losses 2
Water requirements decrease with renal failure, congestive heart failure, and mechanical ventilation 2