Clinical bottom line
Vitamin D deficiency is common in pediatric populations worldwide and can contribute to rickets, impaired bone health, and possibly other systemic effects. Current evidence supports targeted screening in high-risk children rather than universal testing. Supplementation with vitamin D3 (cholecalciferol) at doses tailored to age and deficiency severity is effective and safe for correcting deficiency and preventing complications. Routine high-dose supplementation without confirmed deficiency is not recommended. Clinicians should consider risk factors such as limited sun exposure, darker skin pigmentation, malabsorption syndromes, and exclusive breastfeeding without supplementation. Monitoring serum 25-hydroxyvitamin D [25(OH)D] levels guides therapy but should be interpreted in clinical context.
What the evidence shows
Recent clinical practice guidelines and systematic reviews emphasize a risk-based approach to pediatric vitamin D deficiency management. The 2023 Endocrine Society guideline update recommends screening children with risk factors including prematurity, obesity, chronic kidney disease, malabsorption, or dark skin living in higher latitudes (Holick MF, et al. 2023). Universal screening is not supported by current evidence due to low yield and cost-effectiveness concerns.
Vitamin D deficiency is defined variably, but serum 25(OH)D levels below 20 ng/mL (50 nmol/L) are generally considered deficient, with insufficiency between 20-30 ng/mL (50-75 nmol/L) (Pludowski P, et al. 2018). Supplementation with vitamin D3 is preferred over D2 due to better efficacy in raising serum levels (Tripkovic L, et al. 2017). Typical regimens for deficiency correction range from 2000 IU/day for 6 weeks to 50,000 IU weekly for 6 weeks in older children, followed by maintenance dosing of 400-1000 IU/day depending on age and risk factors.
A 2021 Cochrane review of randomized controlled trials (RCTs) in children found that vitamin D supplementation reduces the risk of rickets and improves bone mineral density in deficient populations but showed limited evidence for benefits beyond bone health in otherwise healthy children (Winzenberg TM, et al. 2021). Adverse effects are rare when dosing guidelines are followed, but excessive dosing can cause hypercalcemia and toxicity.
Caveats and uncertainty
There remains variability in defining optimal serum 25(OH)D thresholds for deficiency and sufficiency in children, partly due to differences in assay methods and population heterogeneity. Most evidence focuses on bone outcomes; data on extraskeletal effects (immune function, respiratory infections) are less conclusive and sometimes conflicting.
The ideal supplementation dose and duration may differ by age, baseline vitamin D status, and comorbidities, but high-quality pediatric RCTs comparing regimens are limited. Long-term safety data for high-dose supplementation in children are sparse. Also, the impact of vitamin D supplementation on growth and neurodevelopmental outcomes is not well established.
Screening strategies vary internationally, and cost-effectiveness analyses are limited. The risk of overdiagnosis and overtreatment exists if screening is applied indiscriminately. Clinical judgment remains essential to balance benefits and harms.
How this may change practice
Primary care clinicians should adopt a risk-based screening approach for vitamin D deficiency in children rather than universal testing. Identifying high-risk groups (e.g., exclusively breastfed infants without supplementation, children with limited sun exposure or malabsorption) enables targeted testing and intervention.
When deficiency is confirmed, vitamin D3 supplementation tailored to age and severity should be initiated, with follow-up serum 25(OH)D measurement to assess response. Routine supplementation in children without risk factors or confirmed deficiency is not currently supported.
Education for families on safe sun exposure, dietary sources of vitamin D, and adherence to supplementation regimens is important. Clinicians should remain aware of evolving evidence, particularly regarding extraskeletal benefits and optimal dosing strategies.