Vitamin D insufficiency and bone fractures in patients on maintenance hemodialysis

The incidence of fractures is substantially increased in patients with chronic kidney disease (CKD) compared to the general population. The factors associated with increased bone fracture in this population are not well understood. Vitamin D deficiency has been associated with decreased bone mass and higher incidence of fractures in the general population. In this study, we aimed to assess the association between fracture and vitamin D status and other factors potentially associated with fracture in patients on maintenance hemodialysis. One hundred and forty-four patients were assessed and interviewed about previous low-trauma fractures. Evidence of fracture was obtained from medical records and also through patient interviews. Routine laboratory results were collected from medical records. Serum intact PTH (iPTH) and 25(OH) vitamin D-3 were measured. All patients underwent bone densitometry of the lumbar spine, femoral neck and distal radius. Bone quality was also assessed with quantitative bone ultrasound (QUS). Descriptive statistics, logistic regression models were used to analyze factors associated with fractures. One hundred and thirty patients were included in the final analysis. Patients with fractures (n = 21) had lower 25(OH) vitamin D-3 levels (15.8 nmol/l (interquartile range, IQR: 27) vs. 30.0 nmol/l (IQR: 28.5), P = 0.029), were more likely females, had longer duration of end-stage kidney disease, and lower bone mineral density (BMD) at the distal radius. QUS parameters were not associated with fractures. Multivariate analyses revealed that serum 25(OH) vitamin D-3 concentration, BMD at the radius, iPTH less than 100 pg/ml and history of fractures were independent predictors of new bone fracture after the initiation of dialysis therapy. Increased bone fragility in dialysis patients is associated with vitamin D deficiency and relative hypoparathyroidism in addition to reduced BMD at the radius. Further studies are needed to determine whether patients with vitamin D deficiency benefit from vitamin D supplementation to reduce fracture risk.