Failed kidney cannot activate vitamin D, so measured vitamin D (before kidney) is not relevant
British Journal of Medicine and Medical Research 2015 Vol. 6 No. 4 pp. 439-445
ISSN 2231-0614 DOI 10.9734/BJMMR/2015/14532
Background: Although lack of Vitamin D is widespread in chronic kidney disease, data is scarce in the role Vitamin D may play in fractures in such cases. Methods: Retrospective analysis of all patients visiting Nephrology outpatients department in 1 UK District General Hospital over 2 years. Chronic kidney disease was categorised by estimated glomerular filtration rate, total Vitamin D and fracture details obtained from Hospital Information Technology system. Total Vitamin D <50 nmol/L was considered inadequate. Logistic regression was used to assess the relationships of eGFR and total Vitamin D with fracture incidence. Spearman's correlation coefficient (rs) was used to assess the relationship between continuous variables.
Results: 43/66 patients were Vitamin D deficient - prevalence of Vitamin D deficiency was 65% (95% CI: 52%, 76%). 20/66 patients sustained any form of fracture, incidence of fracture in this chronic kidney disease population was 30% (95% CI: 20%, 43%). There was no association between total Vitamin D level and risk of fracture, OR 0.99 (95% CI: 0.97, 1.01), p=0.316. The strength of the association between total Vitamin D level and fracture was also unrelated to estimated glomerular filtration level (interaction test, p=0.971). There was no relationship between estimated glomerular filtration and total Vitamin D level (rs=-0.03, p=0.8066). Estimated glomerular filtration was found to be negatively associated with risk of fracture, OR 0.96 (0.93, 1.00), p=0.028.
Conclusion: Vitamin D deficiency appears widely prevalent in chronic kidney disease with a third of patients sustaining fractures; total Vitamin D levels however are unrelated to fractures. Prospective interventional studies can help answer if earlier replacement of Vitamin D before chronic kidney disease develops will help improve musculoskeletal health and prevent fractures.