Evaluation of vitamin K status and rationale for vitamin K supplementation in dialysis patients (Caluwé R et al.)
A review paper published lately in Nephrology Dialysis Transplantation presents a broad insight into ways of evaluating and optimizing vitamin K status among chronic kidney disease (CKD) populations.
The authors cast more light on the validity and interpretation of the available tests to assess vitamin K status and discuss the impact of different dosing regimens and the choice of vitamin K species. They also review the extant evidence on the effects of vitamin K supplementation in high-risk populations, in particular in haemodialysis patients, on cardiovascular disease and other relevant outcome parameters. To this end, the PubMed.gov and ClinicalTrials.gov databases were searched in May 2018.
Tabular summaries of numerous studies have been included in the paper: studies evaluating vitamin K intake in chronic kidney disease, studies evaluating vitamin K status in CKD, association between vitamin K status and cardiovascular outcome in CKD populations, dose-finding studies of vitamin K2 in haemodialysis patients. The potential beneficial effects of long-term vitamins K1 and K2 supplementation on cardiovascular disease, bone density and fracture risk, and insulin resistance have been the subject of a large number of randomized controlled trials (RCTs). The results of these trials have been included in tables 5–7. The last table in the paper presents several trials of vitamin K supplements that have been initiated recently in prevalent or incident haemodialysis patients. Most use a specific form of vitamin K2 called MenaQ7 as supplement, generally with thrice weekly administration after dialysis to ascertain compliance. Surrogate markers for cardiovascular disease under study are coronary artery calcification score and arterial stiffness measures such as pulse wave velocity.
The authors concluded that, “when we have delineated how to define, measure and optimize vitamin K status in dialysis patients, we will need to demonstrate that repletion of vascular vitamin K stores effectively slows the development of vascular calcifications and—most importantly—that this translates into an improved cardiovascular outcome.”
“Clinical trials with MenaQ7 that are ongoing in Singapore, Belgium, USA and Denmark show huge interest of vitamin K2 supplementation in kidney patients,” says Dr. Katarzyna Maresz, president of the International Science and Health Foundation. “This noteworthy paper clearly demonstrates the large potential of MenaQ7 supplementation as a means to improve cardiovascular health in populations prone to severe calcification, namely CKD and dialysis patients.”
Caluwé R, Verbeke F, De Vriese AS (2018) Evaluation of vitamin K status and rationale for vitamin K supplementation in dialysis patients, Nephrology Dialysis Transplantation, gfy373, doi: 10.1093/ndt/gfy373