Measurement of des-gamma-carboxy prothrombin levels in hemodialysis patients positive for anti-hepatitis virus C antibody

Hepatic and Vascular Vitamin K Status in Patients with High Cardiovascular Risk

Vitamin K dependent proteins (VKDP), such as hepatic coagulation factors and vascular matrix Gla protein (MGP), play key roles in maintaining physiological functions. Vitamin K deficiency results in inactive VKDP and is strongly linked to vascular calcification (VC), one of the major risk factors for cardiovascular morbidity and mortality. In this study we investigated how two vitamin K surrogate markers, dephosphorylated-undercarboxylated MGP (dp-ucMGP) and protein induced by vitamin K absence II (PIVKA-II), reflect vitamin K status in patients on hemodialysis or with calcific uremic arteriolopathy (CUA) and patients with atrial fibrillation or aortic valve stenosis. Through inter- and intra-cohort comparisons, we assessed the influence of vitamin K antagonist (VKA) use, vitamin K supplementation and disease etiology on vitamin K status, as well as the correlation between both markers. Overall, VKA therapy was associated with 8.5-fold higher PIVKA-II (0.25 to 2.03 AU/mL) and 3-fold higher dp-ucMGP (843 to 2642 pM) levels. In the absence of VKA use, non-renal patients with established VC have dp-ucMGP levels similar to controls (460 vs. 380 pM), while in HD and CUA patients, levels were strongly elevated (977 pM). Vitamin K supplementation significantly reduced dp-ucMGP levels within 12 months (440 to 221 pM). Overall, PIVKA-II and dp-ucMGP showed only weak correlation (r2 ≤ 0.26) and distinct distribution pattern in renal and non-renal patients. In conclusion, VKA use exacerbated vitamin K deficiency across all etiologies, while vitamin K supplementation resulted in a vascular VKDP status better than that of the general population. Weak correlation of vitamin K biomarkers calls for thoughtful selection lead by the research question. Vitamin K status in non-renal deficient patients was not anomalous and may question the role of vitamin K deficiency in the pathogenesis of VC in these patients.

Utility of serological tumor biomarkers for surveillance of hepatocellular carcinoma in patients undergoing dialysis

BACKGROUND

Patients undergoing dialysis are at risk of hepatocellular carcinoma (HCC) and preferably should undergo HCC surveillance. We investigated the utility of HCC tumor markers for HCC surveillance in patients undergoing dialysis.

METHODS

Three serum markers specific for HCC, namely alpha-fetoprotein (AFP), Lens culinaris agglutinin A-reactive fraction of AFP (AFP-L3) and des-gamma-carboxy prothrombin (DCP), were measured in dialysis patients with and without a diagnosis of HCC (n = 60 and 507, respectively). The predictive value of each marker and that of a diagnostic score (GALAD score) based on patient age and gender as well as the same three markers were evaluated by receiver-operating characteristic (ROC) analysis, as well as sensitivity and specificity.

RESULTS

AFP, DCP and the GALAD scores showed high predictive values for HCC, with areas under the ROC curve of >0.85. This effectiveness remained when focusing on small HCC (≤3 cm or ≤2 cm) or early-stage HCC (Stage I), as well as after propensity score matching of background characteristics of HCC and non-HCC patients. In particular, DCP and GALAD score had excellent predictive abilities for HCC.

CONCLUSIONS

Measuring serum tumor markers for HCC can serve as a complement to imaging studies in the surveillance of HCC in patients undergoing dialysis, and reduce the likelihood of advanced HCC at detection and diagnosis.

Evaluation of vitamin K status and rationale for vitamin K supplementation in dialysis patients

The cardinal biological role of vitamin K is to act as cofactor for the carboxylation of a number of vitamin K-dependent proteins, some of which are essential for coagulation, bone formation and prevention of vascular calcification. Functional vitamin K deficiency is common and severe among dialysis patients and has garnered attention as a modifiable risk factor in this population. However, no single biochemical parameter can adequately assess vitamin K status. For each biological function of vitamin K, the degree of carboxylation of the relevant vitamin K-dependent protein most accurately reflects vitamin K status. Dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP) is the best biomarker for vascular vitamin K status when cardiovascular endpoints are studied. Dp-ucMGP levels are severely elevated in haemodialysis patients and correlate with markers of vascular calcification and mortality in some but not all studies. The aetiology of vitamin K deficiency in haemodialysis is multifactorial, including deficient intake, uraemic inhibition of the vitamin K cycle and possibly interference of vitamin K absorption by phosphate binders. The optimal vitamin K species, dose and duration of supplementation to correct vitamin K status in dialysis patients are unknown. Dp-ucMGP levels dose-proportionally decrease with supraphysiological vitamin K2 supplementation, but do not normalize even with the highest doses. In the general population, long-term vitamin K1 or K2 supplementation has beneficial effects on cardiovascular disease, bone density and fracture risk, and insulin resistance, although some studies reported negative results. In haemodialysis patients, several trials on the effects of vitamin K on surrogate markers of vascular calcification are currently ongoing.

Characteristics and Prognosis of Hepatocellular Carcinoma in Japanese Patients Undergoing Dialysis

Patients with end-stage renal disease who are undergoing dialysis may be at high risk of developing hepatocellular carcinoma (HCC). We investigated the characteristics and prognosis of HCC in patients undergoing dialysis in Japan. Patients characteristics, progression of HCC at diagnosis, and survival rates after diagnosis were compared between 108 HCC patients undergoing dialysis and 526 non-dialysis patients followed up at liver center. The comparisons were also performed after adjusting for patient age, gender, platelet count, and etiology using propensity-score matching. HCC was more advanced in patients undergoing dialysis than in non-dialysis controls. The 3- and 5-year survival rates of patients undergoing dialysis were 56.3% and 38.3%, respectively, which were lower than those of non-dialysis controls (66.5% and 52.7%, respectively, P = 0.0026). The results were the same after propensity score matching (P = 0.0014). In Japan, HCC was more advanced at diagnosis in patients undergoing dialysis in comparison to HCC in patients at liver centers, resulting in a lower survival rate after diagnosis.

Upregulation of des-gamma-carboxy-prothrombin after portal vein embolization in a cirrhotic patient with hepatocellular carcinoma

A 73-year-old female with hepatocellular carcinoma (HCC) received percutaneous transhepatic portal vein embolization (PTPE) before extensive right lobe hepatectomy. Serum levels of des-gamma-carboxy-prothrombin (DCP) were increased and remained at a high level until hepatectomy. Immunohistochemical examination revealed that an increased expression of DCP was demonstrated not only in HCC tissues, but also in the non-cancerous liver of the right lobe, where portal blood flow was blocked off as a result of PTPE. The serum level of DCP is known to be greatly increased in patients with HCC accompanied by portal vein invasion. We speculate that this increased DCP level is caused by both increased DCP production in HCC tissue and the surrounding non-cancerous liver, where portal flow is blocked off as a result of portal invasion by HCC.

Assessment of potential biomarkers of subclinical vitamin K deficiency in patients with end-stage kidney disease

BACKGROUND

A significant proportion of hemodialysis patients have functional, but modifiable, vitamin K deficiency.

OBJECTIVE

To determine the correlates of poor vitamin K status in hemodialysis patients.

DESIGN

Cross-sectional study.

SETTING

Hemodialysis units at Kingston General Hospital and its satellite centres, Ontario, Canada.

PATIENTS

Patients undergoing outpatient hemodialysis for end-stage kidney disease.

MEASUREMENTS

Serum concentrations of phylloquinone, undercarboxylated prothrombin, also known as protein induced by vitamin K absence or antagonism - factor II (PIVKA-II), and the percentage of undercarboxylated osteocalcin (%ucOC).

METHODS

Vitamin K status was determined in fasting blood samples of hemodialysis patients. Bivariate relationships were examined using parametric and non-parametric statistics as appropriate. Multivariable linear regression models were applied to identify predictors of vitamin K status.

RESULTS

Among 44 HD patients, criteria for subclinical vitamin K deficiency were met in 13.6% (phylloquinone < 0.4 nmol/L), 51% (%ucOC > 20%) and 90.9% (PIVKA-II > 2.0 nmol/L) of subjects. Phylloquinone levels were positively associated with total cholesterol, triglyceride levels and non-smoking status. Higher %ucOC was associated with increased calcium-phosphate product. Increased PIVKA-II levels were observed with advancing age, reduced dialysis adequacy, lower HDL and a history of coronary artery disease. There were no associations found among the individual biomarkers of vitamin K status. In a multi-variable model, triglycerides were the only significant predictor of phylloquinone levels, while increasing phosphate and decreasing PTH were independent predictors of %ucOC. PIVKA-II levels increased by 0.54 nmol/L for every 10-year increase in age.

LIMITATIONS

Observational study; small sample size.

CONCLUSIONS

A significant proportion of HD patients met criteria for subclinical vitamin K deficiency. Of the biomarkers measured, PIVKA-II may be superior given its independence of renal function or dyslipidemia, both of which may confound the other vitamin K biomarkers. Studies in patients with ESKD linking biomarkers of vitamin K status to important patient outcomes, including cardiovascular disease, nutritional status and mortality, are required in order to determine the optimal biomarker for evaluating vitamin K status in this particular population.