Poor vitamin K status is associated with inflammation and low areal bone mineral density (BMD) among patients with end-stage renal disease (ESRD), conferring an increased risk for incident fractures among de novo renal transplant recipients, according to findings from an analysis published in the Journal of Bone and Mineral Research.
Recognizing that vitamin K insufficiency is common among patients with ESRD, the researchers sought to explore several aspects of bone health among recipients of de novo renal transplant to explore the association among vitamin K status, inflammation, BMD, and incident clinical fractures. Parameters of mineral metabolism and inflammation were assessed from blood samples that were obtained prior to kidney transplantation in 468 patients.
Areal BMD was measured at the lumbar spine and femoral neck using dual-energy x-ray absorptiometry within 14 days posttransplantation. Data showed that poor vitamin K status (dephosphorylated-uncarboxylated Matrix Gla Protein [dp-ucMGP] >500 nmol/L) was highly prevalent (90% of patients). High dp-ucMGP concentrations were independently associated with elevated inflammatory markers and low areal BMD.
There were no associations reported between vitamin K status and bone turnover markers. At a median 5.1-year follow-up, 33 patients had sustained a fragility fracture. According to Cox proportional hazards analysis, a dp-ucMGP level above the median was linked with incident fractures, which were independent of classical determinants, including gender, age, history of fracture, and areal BMD (hazard ratio, 2.21; 95% CI, 1.00-4.91; P <.05).
The investigators concluded that poor vitamin K status at the time of renal transplantation can be considered a risk factor for the development of incident fractures. Considering the observational nature of this study, randomized trials are warranted to examine whether vitamin K supplementation can improve vitamin K status and mitigate inflammation or alter bone outcomes among patients with chronic kidney disease.
Evenepoel P, Claes K, Meijers B, et al. Poor vitamin K status is associated with low bone mineral density and increased fracture risk in end-stage renal disease [published online November 14, 2018]. J Bone Miner Res. doi: 10.1002/jbmr.3608