Calcium and Vitamin D Dosing for a 21kg Pediatric Patient
Recommended Dosages
For a 21kg child (approximately 6-7 years old), provide 600 IU of vitamin D daily and 800-1000 mg of elemental calcium daily from combined dietary and supplemental sources. 1
Vitamin D Supplementation
Standard Maintenance Dosing
- Children ages 1-18 years require 600 IU/day of vitamin D from all sources (diet plus supplements) 1
- This dosing is endorsed by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN), the American Academy of Pediatrics, and the Institute of Medicine 1
- Cholecalciferol (vitamin D3) is preferred over ergocalciferol (vitamin D2) due to higher bioefficacy 1
Safety Thresholds
- The upper tolerable limit for children ages 4-8 years is 3,000 IU/day 1
- Prolonged daily intake up to 10,000 IU appears safe, but serum concentrations >375 nmol/L are associated with acute hypercalcemia and hyperphosphatemia 1
- The target serum 25(OH)D level is >50 nmol/L (20 ng/mL) to indicate sufficiency 1
Treatment for Deficiency (if applicable)
- If the child has documented vitamin D deficiency (25(OH)D <20 ng/mL), use 2,000 IU daily for 12 weeks or 50,000 IU every other week for 12 weeks 1
- After treatment, recheck 25(OH)D levels and transition to maintenance dosing of 600 IU/day 1
Calcium Supplementation
Age-Appropriate Calcium Requirements
- A 21kg child (approximately 6-7 years old) requires 800-1000 mg of elemental calcium daily from all sources 2
- First assess dietary calcium intake from milk, dairy products, and fortified foods 2
- Supplement only the difference between dietary intake and the recommended total 2
Calcium Salt Selection
- Calcium carbonate (40% elemental calcium) is well-tolerated and cost-effective 2
- Calcium citrate (21% elemental calcium) has approximately 24% better absorption than calcium carbonate and does not require meals for absorption 3, 4
- Calcium gluconate (9% elemental calcium), lactate (13% elemental calcium), and acetate (25% elemental calcium) are also acceptable alternatives 2
Practical Dosing Example
- If dietary calcium intake is 400 mg/day, supplement with 400-600 mg of elemental calcium daily to reach the 800-1000 mg total 2
- This translates to approximately 1000-1500 mg of calcium carbonate (providing 400-600 mg elemental calcium) 2
- Divide calcium doses throughout the day with meals to optimize absorption 3, 5
Clinical Considerations and Pitfalls
Important Caveats
- Avoid calcium chloride as it may cause metabolic acidosis 2
- Consider the phosphorus content of dairy products if the child has any renal concerns 2
- Fortified products provide calcium bioavailability comparable to milk 2
- Foods high in phytates (like bran cereal) may have poor calcium bioavailability 2
Monitoring Strategy
- Monitor 25(OH)D levels every 6-12 months, especially during winter months when sun exposure is limited 1
- For children on long-term supplementation, periodic assessment ensures adequacy without toxicity 1
Special Populations Requiring Adjustment
- Children with chronic kidney disease require individualized dosing based on PTH levels, dialysate calcium concentration, and risk of calcium overload 2
- Children with malabsorption may require higher doses or alternative formulations 1
- Active vitamin D analogs should not be used to treat nutritional vitamin D deficiency 1