Pediatric Vitamin D Levels
For pediatric patients, target serum 25-hydroxyvitamin D (25(OH)D) levels should be maintained at a minimum of 20 ng/mL (50 nmol/L), though levels of 30 ng/mL or higher may provide additional skeletal and extra-skeletal benefits. 1, 2
Defining Vitamin D Status in Children
The classification of vitamin D status in pediatric patients follows these thresholds:
- Deficiency: 25(OH)D <20 ng/mL (50 nmol/L) 2, 3
- Insufficiency: 25(OH)D 20-30 ng/mL (50-75 nmol/L) 2, 3
- Sufficiency: 25(OH)D ≥20 ng/mL (50 nmol/L) for bone health 1, 4
- Optimal: 25(OH)D ≥30 ng/mL (75 nmol/L) for extra-skeletal benefits 4, 5
Target Levels: The Guideline Debate
There is ongoing debate between major organizations regarding optimal targets. The European Cystic Fibrosis Bone Mineralization Guidelines recommend a minimum threshold of 20 ng/mL (50 nmol/L), while the US Cystic Fibrosis Foundation recommends levels above 30 ng/mL (75 nmol/L) for presumed extra-skeletal health benefits. 1 For general pediatric practice, maintaining levels at or above 20 ng/mL is sufficient for bone health, but targeting 30 ng/mL or higher is reasonable when considering broader health outcomes. 2, 4
Age-Specific Supplementation for Maintenance
Once deficiency is corrected, maintenance dosing varies by age:
- Infants <12 months: 400 IU/day 2, 3, 6
- Children 1-18 years: 600 IU/day 2, 5, 6
- Adolescents requiring higher intake: Up to 1,000 IU/day may be needed 5, 6
For infants with cystic fibrosis or malabsorption, starting doses of 400 IU/day can be advanced to an upper limit of 1,000 IU/day based on serum monitoring. 1
Treatment of Deficiency in Children
When 25(OH)D levels fall below 20 ng/mL, treatment protocols include:
For severe deficiency (<20 ng/mL):
For insufficiency (20-30 ng/mL):
After the 12-week treatment period, recheck 25(OH)D levels to confirm normalization, then transition to age-appropriate maintenance dosing. 2
Monitoring Frequency
Annual monitoring is recommended for all pediatric patients, preferably at the end of winter months when sun exposure is lowest. 1, 2 Check levels 3-6 months after any dosage change to ensure therapeutic targets are achieved. 1
Safety Considerations and Upper Limits
Tolerable upper intake levels by age are well-established:
- Infants 0-6 months: 1,000 IU/day maximum 2
- Infants 7-12 months: 1,500 IU/day maximum 2
- Children 1-3 years: 2,500 IU/day maximum 2
- Children 4-8 years: 3,000 IU/day maximum 2
- Children 9-18 years: 4,000 IU/day maximum 2
Vitamin D toxicity is rare at recommended doses but manifests as hypercalcemia and hyperphosphatemia when serum concentrations exceed 375 nmol/L (150 ng/mL). 2, 7
Special Populations
Children with cystic fibrosis or malabsorption syndromes require higher doses and more frequent monitoring due to impaired fat-soluble vitamin absorption. Starting doses of 800 IU/day can be advanced to upper limits of 2,000 IU/day for children 1-10 years, and 4,000 IU/day for older children, with dose adjustments based on annual serum values. 1
Children with chronic kidney disease may require different targets and should not receive active vitamin D analogs (calcitriol, alfacalcidol) for treatment of nutritional vitamin D deficiency. 1, 2
Critical Clinical Pitfalls
- Never use active vitamin D analogs (calcitriol, doxercalciferol, paricalcitol) to treat nutritional vitamin D deficiency—these are reserved for specific conditions like advanced CKD. 1, 2
- Ensure adequate calcium intake during vitamin D treatment, as vitamin D enhances calcium absorption and deficiency correction without adequate calcium can worsen bone health outcomes. 7
- Cholecalciferol (vitamin D3) is preferred over ergocalciferol (vitamin D2) for supplementation, as D3 demonstrates higher bioefficacy and maintains levels longer. 1, 7
- Monitor for clinical manifestations of rickets in severely deficient children, including assessment of serum calcium, phosphorus, alkaline phosphatase, and parathyroid hormone. 2