The effect of six-month oral vitamin K supplementation on calcification propensity time in individuals with type 2 diabetes mellitus: A post hoc analysis of a randomized, double-blind, placebo-controlled trial

BACKGROUND AND AIMS

Experimental studies suggested that vitamin K supplementation may retard arterial calcification. Recently, serum calcification propensity time (T50) has been suggested as a functional biomarker for arterial wall calcification propensity. In this post-hoc analysis of a clinical trial, we evaluated the effect of six-month oral vitamin K supplementation on T50 and assessed the correlation between T50 and imaging arterial calcification parameters in people with type 2 diabetes (T2DM).

METHODS

This double-blind, randomized, placebo-controlled trial included 68 participants (age = 69 ± 8 years, 76% male) with T2DM. Participants were assigned to menaquinone-7 (360 μg/day; n = 35) or placebo (n = 33). T50 was measured via nephelometry in serum collected at baseline, three and six months. Arterial calcification was measured at baseline and six months via 18F-Na PET-CT and conventional CT using Target-to-Background ratio (TBR) and Agatston score. Longitudinal analysis of covariance adjusted for baseline T50 was used to study the treatment effect. Spearman's correlation was used to assess the correlation between T50 and imaging calcification parameters.

RESULTS

Median baseline T50 was similar in the vitamin K (350 [321-394] minutes) and placebo groups (363 [320-398]). There was no significant difference in T50 between treatment arms over time (ẞ = 1.00, 95%C.I. = 0.94-1.07, p = 0.982). The correlation coefficient of T50 with TBR and Agatston score at baseline were -0.185 (p = 0.156) and -0.121 (p = 0.358), respectively.

CONCLUSIONS

No effect of vitamin K supplementation on T50 was observed in T2DM. Moreover, T50 did not correlate with TBR and Agatston score. Further research on vitamin K in arterial calcification and on the validity of T50 as arterial calcification marker is warranted.

Association of renal function with bone mineral density and fracture risk in the Longitudinal Aging Study Amsterdam

Early renal dysfunction is associated with a 38% increased fracture risk in individuals aged 65 years and older. In men but not women, early renal dysfunction is associated with decreased femoral neck bone mineral density (BMD) which can be partially explained by increased parathyroid hormone (PTH) concentrations.

INTRODUCTION

It is uncertain whether early renal dysfunction is associated with osteoporosis and increased fracture risk. The aim of this study was to determine the relationship of decreased renal function with BMD and fracture risk and the role of PTH therein.

METHODS

We analyzed data of participants aged 65 years and older from the Longitudinal Aging Study Amsterdam. A 6-year fracture follow-up was obtained in 1477 participants. BMD was measured by dual-energy x-ray absorptiometry (n = 535) and vertebral fractures by lateral spinal radiograph (n = 527) in a subsample at baseline. Glomerular filtration rate (eGFR) was estimated according to the modification of diet in renal disease equation and assessed by the five stages of chronic kidney disease (CKD).

RESULTS

In men and women, eGFR < 57 ml/min/1.73 m2 (lowest quartile) compared to eGFR > 74 ml/min/1.73 m2 (highest quartile) was associated with a 38% increase in fracture risk after adjustment for relevant confounders [hazard ratio (95%CI): 1.38 (1.17 to 1.61)]. Also, CKD stages 3a and 3b were associated to a 28 and 46% increase in fracture risk, respectively, as compared to CKD stages 1 and 2 together (eGFR > 60 ml/min/1.73 m2) after adjustment for confounders. Renal function was not associated with prevalent vertebral fractures. In men, but not women, lowest quartile of eGFR was related to lower femoral neck BMD as compared to the highest quartile eGFR [unstandardized B (95%CI) - 0.052 g/cm2 (- 0.098 to - 0.006)], after adjustment for relevant confounders. Further adjustment for PTH attenuated this relationship by 27%.

CONCLUSIONS

In men and women, early decreased renal function (eGFR < 60 ml/min/1.73 m2) was related to increased incident any fracture risk but not with increased prevalence of vertebral fractures. In men, but not women, early renal dysfunction was related to lower femoral neck BMD which could statistically be partially explained by increased PTH concentrations.

Clinical utility of bone markers in various diseases

Measurements of bone markers (BMs) in peripheral blood or urine are a pivotal part of bone research within modern clinical medicine. In recent years the use of BMs increased substantially as they can be useful either to diagnose bone (related) disease and to follow its natural history, but also to monitor the effects of interventions. However, the use of BMs is still complicated mainly due to (pre)analytical variability of these substances, limited accessibility of assays, variable cut-off values in different countries and laboratories and heterogeneous results with regard to clinical implications of measuring BMs in several studies. This review will provide the clinician with a practical guide, based on current evidence, in which circumstances to test which bone markers for optimal diagnostic purposes, in order to improve patient care in different areas of bone diseases including Paget's disease, primary osteoporosis, tumor induced osteomalacia, hypophosphatemic rickets, van Buchem disease, chronic kidney disease, rheumatoid arthritis, neoplasma/multiple myeloma, type 2 diabetes mellitus and primary hyperparathyroidism. The clinician should consider fasting state, recent fractures, aging, menopausal status, concomitant liver and kidney disease when ordering and interpreting BM measurements as these factors might result in misleading BM concentrations. We found that BMs are clearly useful in the current diagnosis of tumor induced osteomalacia, van Buchem disease, Paget's disease and hypophosphatemic rickets. In addition, BMs are useful to monitor disease activity in chronic kidney disease, Paget's disease and are useful to monitor treatment adherence in osteoporosis.

Phosphate binders affect vitamin K concentration by undesired binding, an in vitro study

Background

Vascular calcification is a major contributing factor to mortality in end stage renal disease (ESRD). Despite the efficacy of phosphate binders to improve hyperphosphatemia, data on vascular calcification are less clear. There seems to be a difference in attenuation or delay in progression between different binders. In this in vitro experiment we tested whether phosphate binders could limit bioavailability of vitamin K2 by undesired binding. Vitamin K-deficiency limits activation of the vascular tissue mineralization inhibitor matrix γ-carboxyglutamate (Gla) protein (MGP) thereby exacerbating vascular calcification.

Methods

In this experiment vitamin K2 (menaquinone-7; MK-7) binding was assessed by adding 1 mg of vitamin K2 to a medium with pH 6 containing 67 mg phosphate binder with either 7 mg of phosphate or no phosphate. Five different phosphate binders were tested. After five and a half hours vitamin K was analyzed by HPLC. All experiments were performed in triplicate.

Results

Sucroferric-oxyhydroxide and sevelamer carbonate did not significantly bind vitamin K2, both in solution only containing vitamin K2 or in combination with phosphate. Calcium acetate/magnesium carbonate binds vitamin K2 strongly both in absence (p = 0.001) and presence of phosphate (p = 0.003). Lanthanum carbonate significantly binds vitamin K2 in solution containing only vitamin K2 (p = 0.005) whereas no significant binding of vitamin K2 was observed in the solution containing vitamin K2 and phosphate (p = 0.462). Calcium carbonate binds vitamin K2 significantly in a solution with vitamin K2 and phosphate (p = 0.009) whereas without phosphate no significant binding of vitamin K2 was observed (p = 0.123).

Conclusions

Sucroferric-oxyhydroxide and sevelamer carbonate were the only binders of the five binders studied that did not bind vitamin K2 in vitro. The presence or absence of phosphate significantly interferes with vitamin K2 binding so phosphate binders could potentially limit bioavailability vitamin K2.

Feasibility of long-term continuous subcutaneous magnesium supplementation in a patient with irreversible magnesium wasting due to cisplatin

A 39-year-old woman presented with severe, uncontrolled and irreversible hypomagnesaemia, following cisplatin treatment in her childhood. Because high-dose oral magnesium supplementation therapy was insufficient and not tolerated, continuous subcutaneous magnesium supplementation was successfully instituted and continued in the outpatient setting. This case demonstrates that continuous subcutaneous magnesium supplementation is effective in maintaining magnesium levels within the normal range, is well tolerated and may provide a long-term solution for chronic hypomagnesaemia due to intractable renal losses.

Fish and omega-3 fatty acid intake in relation to circulating fibroblast growth factor 23 levels in renal transplant recipients

BACKGROUND AND AIMS

A high circulating fibroblast growth factor 23 (FGF23) level is an independent risk factor for cardiovascular mortality in renal transplant recipients and the general population. N-3 fatty acids eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) may contribute to cardiovascular risk reduction. We investigated whether fish and EPA-DHA intake are related to FGF23 levels in renal transplant recipients.

METHODS AND RESULTS

We performed a cross-sectional analysis in 619 stable renal transplant recipients (mean age 53 years, 57% male, estimated glomerular filtration rate [eGFR] 53 ± 20 mL/min/1.73 m(2)). Dietary intake was assessed by a 177-item food frequency questionnaire. Serum intact FGF23 was measured by ELISA. We examined differences in FGF23 levels across categories of fish and EPA-DHA intake using analysis of variance models adjusted for age, sex, dietary and lifestyle factors and key determinants of FGF23. Patients consumed on average 15 g of fish and 139 mg EPA-DHA/day. Median FGF23 was 62 pg/mL (IQR 43-98 pg/mL). Higher dietary EPA-DHA and fish intake were associated with lower serum FGF23 levels. Subgroup analyses revealed that particularly in patients with reduced renal function (eGFR <60 mL/min/1.73 m(2)), adjusted FGF23 levels (114, 79, 75 pg/mL, P = 0.0001) were inversely associated with tertiles of EPA-DHA intake. Similarly, we observed an inverse association between fish consumption and serum FGF23 levels in adjusted analyses.

CONCLUSION

A higher intake of fish and dietary n-3 fatty acids (EPA-DHA) is related to lower circulating FGF23 levels in renal transplant recipients. Further research is needed to assess the causality of this association and the clinical implications.

Renal function 5 years after open and endovascular aortic aneurysm repair from a randomized trial

Background

Deterioration of renal function after major vascular surgery is an important complication, and may vary between patients undergoing endovascular (EVAR) or open surgical (OR) repair of an abdominal aortic aneurysm (AAA). The objective was to determine the impact of OR and EVAR on renal function after 5 years.

Methods

This was a post hoc analysis of data collected prospectively from the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial. Five years after surgery, creatinine levels were available for 189 patients (94 after OR and 95 after EVAR). The severity of renal disease was staged using the chronic kidney disease classification of the US National Kidney Foundation clinical guidelines.

Results

Using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the estimated glomerular filtration rate (eGFR) for the entire group declined over time, with a mean(s.d.) preoperative value of 80·0(7·6) ml per min per 1·73 m2 compared with 75·7(9·7) ml per min per 1·73 m2 after 5 years (mean difference 4·2 (95 per cent confidence interval 3·2 to 5·3) ml per min per 1·73 m2; P &lt; 0·001). Five years after surgery, the mean eGFR (CKD-EPI equation) was not significantly different between the OR and EVAR groups: 76·3(9·3) versus 75·1(10·0) ml per min per 1·73 m2 (mean difference 1·2 (−1·6 to 3·9) ml per min per 1·73 m2; P = 0·410).

Conclusion

Renal function 5 years after OR and EVAR for AAA was similar. Neither surgical procedure accelerated the loss of renal function. Registration number: NCT00421330 (http://www.clinicaltrials.gov).

Cinacalcet for secondary hyperparathyroidism: from improved mineral levels to improved mortality?

Secondary hyperparathyroidism is an almost inevitable complication of advanced kidney failure. The introduction of the calcimimetic cinacalcet for the treatment of secondary hyperparathyroidism in patients on dialysis was based on its ability to reduce elevated levels of parathyroid hormone (PTH). Subsequent clinical studies confirmed the beneficial effects of cinacalcet on biochemical parameters reflecting mineral disturbances and bone disease. In this review we summarise the impact of cinacalcet on biochemical, intermediate and clinical outcomes. We also present previously unpublished mineral metabolism data from 144 Dutch dialysis patients treated with cinacalcet who participated in the pan-European ECHO observational study. Although secondary hyperparathyroidism tended to be more severe in our Dutch cohort, compared with the entire ECHO cohort, cinacalcet was nevertheless effective in reducing PTH in these patients. Two recent clinical studies evaluated, respectively, the efficacy of cinacalcet in improving the intermediate endpoint of cardiovascular calcifications (ADVANCE trial), and its impact on clinical outcomes, including all-cause mortality and cardiovascular events (EVOLVE trial). The ADVANCE trial provided evidence that cinacalcet may indeed improve calcification in both large arteries and cardiac valves. The EVOLVE trial, however, did not meet its clinical primary endpoint (time to all-cause mortality, myocardial infarction, hospitalisation for unstable angina, heart failure or a peripheral vascular event), although secondary and sensitivity analysis suggested a beneficial effect. The clinical implications of these important studies are also addressed in this review.

Dutch guidelines for diagnosis and therapy of proliferative lupus nephritis

Proliferative lupus nephritis is a strong predictor of morbidity and mortality in patients with systemic lupus erythematosus. Despite improvements in the management of lupus nephritis, a significant number of the patients do not respond to immunosuppressive therapy and progress to end-stage renal failure. In order to optimise the diagnostic strategy and treatment of patients with proliferative lupus nephritis, guidelines are needed. In this review, the Dutch Working Party on Systemic Lupus Erythematosus provides recommendations regarding four important areas in patients with proliferative lupus nephritis: I) indications for a first renal biopsy, II ) definitions of treatment response, III ) selection of treatment options, and IV) indications for a repeat biopsy.

[Proatherogenic changes induced by hemodialysis; probably a result of bio-incompatibility]

Chronic haemodialysis patients have a disproportionately high risk for developing cardiovascular disease, which can only in part be explained by known risk factors such as dyslipidaemia, hypertension, hyperhomocysteinemia, diabetes mellitus and chronic volume expansion. A possible cause is that the haemodialysis treatment itself contributes to the accelerated atherosclerosis, observed in these patients. Nowadays, atherosclerosis is considered an inflammatory process, mediated by a dysfunction of the vascular endothelium. As a result, blood cells adhere to the vascular surface and release a variety of vasoactive mediators, cytokines, growth factors and free radicals. Due to the contact between blood and dialyzer, humoral systems and cellular elements are stimulated, and this may be viewed as an inflammatory reaction. As a consequence of this, the vascular surface of haemodialysis patients is repeatedly exposed to the influences of cytokines, coagulation products, vasoactive mediators, stimulated leukocytes and thrombocytes, and oxidative stress. It is therefore conceivable that the haemodialysis treatment itself enhances the greatly increased cardiovascular risk in chronic haemodialysis patients.

Derangements of coagulation and fibrinolysis in critically ill patients with sepsis and septic shock

In patients with sepsis and septic shock, both coagulation and fibrinolysis are activated frequently leading to the syndrome of diffuse intravascular coagulation (DIC). The different mechanisms leading to abnormalities in coagulation and fibrinolysis are discussed in detail. The coagulation and fibrinolytic system appear to be influenced by the septic process largely independently, leading to a procoagulant imbalance between these systems. Coagulation is initiated by mediator-induced expression of tissue factor and is associated with consumption of the natural coagulation inhibitors antithrombin III, protein C, and protein S. As a result, high plasma levels of thrombin-antithrombin complex (TAT) can be found. The effects on fibrinolysis are dominated by (highly) increased levels of plasminogen activator inhibitor type 1 (PAI-1), leading to inadequate fibrinolysis. Although levels of plasminogen activator antigen are increased, its activity is almost completely inhibited by PAI-1. The resulting effects predispose to a procoagulant state, with widespread fibrin deposition, which may be an important mechanism contributing to multiple organ failure. A thorough understanding of the pathophysiological mechanisms underlying the DIC-syndrome is a prerequisite for a rational approach and future therapy for this severe complication of sepsis.