Children with primary immunodeficiency disorders receiving median 1000 IU vitamin D supplementation had a median serum 25(OH)D of 30.75 ng/mL with 13% deficiency prevalence, with serum phosphorus and IgG levels having the greatest influence on 25(OH)D concentration.
Vitamin D deficiency occurred in 13% of all children with primary immunodeficiency disorders tested in this study.
Vitamin D deficiency rates were substantially higher in children with predominantly antibody deficiencies and complement deficiencies compared to the overall cohort.
Serum phosphorus level and immunoglobulin G (IgG) level had the greatest influence on serum 25(OH)D concentration in the multiple linear regression model.
No statistically significant differences in 25(OH)D concentrations were observed among the different IUIS diagnostic groups.
Vitamin D plays an immunomodulatory role and deficiency has been associated with increased risk of infections and autoimmune disorders, but no evidence-based supplementation recommendations specific to children with PIDs currently exist.
The study evaluated multiple clinical and laboratory variables in relation to vitamin D status in children with PIDs.
This research examined vitamin D levels in 132 children who have primary immunodeficiency disorders (PIDs) — conditions where the immune system does not work properly. All children were reportedly taking vitamin D supplements, with a typical dose of 1000 IU per day. The researchers found that, on average, vitamin D blood levels were in an adequate range (30.75 ng/mL), but 13% of all children still had vitamin D deficiency. The problem was more pronounced in specific groups: about 1 in 5 children with antibody deficiencies and 1 in 3 children with complement deficiencies were deficient, suggesting certain PID types may carry greater risk of inadequate vitamin D status even with supplementation. The study also found that two laboratory values — blood phosphorus levels and IgG antibody levels — were the strongest predictors of a child's vitamin D status, more so than the type of immunodeficiency diagnosis itself. Interestingly, children with low IgG levels did not have significantly different vitamin D levels compared to those with normal IgG, which was an unexpected finding. No significant differences in vitamin D levels were seen across the various PID diagnostic categories overall. This research suggests that standard vitamin D supplementation doses used in healthy children may not be sufficient for all children with PIDs, particularly those with antibody or complement deficiencies. However, because the study was retrospective (looking back at existing records) and cross-sectional (a single point in time), it cannot prove that the supplementation directly caused the observed vitamin D levels. The authors call for future prospective studies to better understand how much vitamin D children with different types of PIDs may need, and to develop evidence-based guidelines for this population.
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Upload Your LabsDąbrowska-Leonik N, Grzywa-Czuba R, Wasiak M, Wasil M, Zaczek W, Żebrowska M, et al.. (2026). Vitamin D Status in Children with Primary Immunodeficiency Disorders Receiving Vitamin D Supplementation: A Retrospective Cross-Sectional Study.. Nutrients. https://doi.org/10.3390/nu18172845