Vitamin D Dosing for Children
For healthy children, provide 400 IU/day for infants under 12 months and 600 IU/day for children and adolescents ages 1-18 years, as recommended by ESPGHAN, the American Academy of Pediatrics, and the Institute of Medicine. 1
Standard Maintenance Dosing by Age
- Infants 0-12 months: 400 IU/day from all sources 1
- Children and adolescents 1-18 years: 600 IU/day from all sources 1
- Preterm infants on parenteral nutrition: 200-1000 IU/day (or 80-400 IU/kg/day) 1
These doses maintain serum 25(OH) vitamin D concentrations above 50 nmol/L (20 ng/mL), which indicates sufficiency. 1
Treatment of Vitamin D Deficiency
When treating established deficiency (25(OH)D <20 ng/mL), higher doses are required:
- Loading dose regimen: 2,000 IU daily for 12 weeks, or alternatively 50,000 IU every other week for 12 weeks 2
- After 12 weeks: Recheck levels and transition to maintenance dosing (400-600 IU/day based on age) 2
- Goal: Achieve serum 25(OH)D levels above 20 ng/mL (50 nmol/L) 2
Safety Thresholds - Upper Tolerable Limits
The Institute of Medicine established age-specific upper limits to prevent toxicity: 1
- 0-6 months: 1,000 IU/day maximum
- 7-12 months: 1,500 IU/day maximum
- 1-3 years: 2,500 IU/day maximum
- 4-8 years: 3,000 IU/day maximum
- 9-18 years: 4,000 IU/day maximum
Prolonged daily intake up to 10,000 IU appears safe, but serum concentrations >375 nmol/L are associated with acute hypercalcemia and hyperphosphatemia. 1 Acute vitamin D intoxication is rare and typically results from doses much higher than 10,000 IU/day. 1
Special Populations Requiring Higher Doses
Children on parenteral nutrition need monitoring for deficiency, with additional supplementation if 25(OH)D falls below 50 nmol/L. 1 Oral supplementation should be considered during partial PN and weaning. 1
Children with malabsorption (inflammatory bowel disease, gastric bypass) require higher doses to maintain adequate vitamin D status. 3
Monitoring Strategy
- Target serum level: >50 nmol/L (20 ng/mL) indicates sufficiency 1
- For patients on long-term PN: Monitor periodically for deficiency 1
- After treatment of deficiency: Recheck levels after 12 weeks, then every 6-12 months, especially during winter months 2
Critical Clinical Pitfalls
Breastfed infants are at highest risk for deficiency since breast milk contains minimal vitamin D. These infants require supplementation starting shortly after birth. 4 Children consuming less than 1 liter of vitamin D-fortified milk daily also need supplementation. 4
The 200 IU/day dose is insufficient. A comparative study demonstrated that 21.3% of infants receiving 200 IU/day had levels below 30 mcg/L at 4 months, while none receiving 400 IU/day fell below this threshold. 5 This evidence supports the current 400 IU/day recommendation for infants.
Do not rely on sun exposure alone for vitamin D, particularly given recommendations to keep infants out of direct sunlight and concerns about skin cancer risk from UV-B exposure in childhood. 6, 4