Two out of every three children in Germany with chronic kidney disease (CKD), examined for a research project, were found to be vitamin D deficient, although those taking supplements had better levels of the vitamin than those who were not.
The study, “Genetic, Environmental and Disease-Associated Correlates of Vitamin D Status in Children with CKD,” to be published in a future issue of the Clinical Journal of the American Society of Nephrology, analyzed how various factors are related with vitamin D levels, which are often low in children with CKD.
Serum 25-hydroxy-vitamin D, 1,25-dihydroxy-vitamin D, and 24,25-dihydroxy-vitamin D concentrations were measured in 500 children from 12 European countries, who were diagnosed with CKD stages 3–5. All patients, ages 6 to 18, were enrolled in the Cardiovascular Comorbidity in Children with Chronic Kidney Disease Study. Patients were genotyped for single-nucleotide polymorphisms (SNPs) in the genes encoding 25-hydroxylase, vitamin D binding protein, 7-dehydrocholesterol reductase, and 24-hydroxylase, after which researchers assessed associations of genetic status, season, local solar radiation, oral vitamin D supplementation, and disease-associated factors with vitamin D status.
Results showed that two-thirds of the children were classified as vitamin D deficient. However, patients treated with vitamin D supplements had a lower prevalence of vitamin D deficiency, with their levels often twice as high as patients not taking supplements.
In addition, vitamin D levels were especially lower in children kidney abnormalities like glomerulopathies, and reached their lowest levels in the winter (compared to other seasons). Vitamin D levels were also related to certain genetic variants, but to a lesser extent than disease-associated factors and supplement use.
Importantly, the team showed that the factors associated with vitamin D deficiency in children with CKD can be divided into modifiable and non-modifiable factors.
“Vitamin D levels are influenced more strongly by seasonal factors, the type of disease and nutritional supplementation than by common variants in vitamin D regulating genes. Supplementation practices should be reconsidered and intervention studies are needed to define guidelines how to monitor and treat vitamin D deficiency in children with chronic kidney disease,” study author Anke Doyon, MD, said in a press release.
Vitamin D deficiency is thought to increase a person’s risk of cardiovascular disease, cancer, autoimmune diseases, and osteoporosis.