Real-world usage of Chronic Kidney Disease - Mineral Bone Disorder (CKD-MBD) biomarkers in nephrology practices

Background

Chronic kidney disease mineral bone disorder (CKD-MBD) is a condition characterized by alterations of calcium, phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF-23) metabolism that in turn promote bone disorders, vascular calcifications, and increase cardiovascular (CV) risk. Nephrologists' awareness of diagnostic, prognostic, and therapeutic tools to manage CKD-MBD plays a primary role in adequately preventing and managing this condition in clinical practice.

Methods

A national survey (composed of 15 closed questions) was launched to inquire about the use of bone biomarkers in the management of CKD-MBD patients by nephrologists and to gain knowledge about the implementation of guideline recommendations in clinical practice.

Results

One hundred and six Italian nephrologists participated in the survey for an overall response rate of about 10%. Nephrologists indicated that the laboratories of their hospitals were able to satisfy request of ionized calcium levels, 105 (99.1%) of both PTH and alkaline phosphatase (ALP), 100 (94.3%) of 25(OH)D, and 61 (57.5%) of 1.25(OH)2D; while most laboratories did not support the requests of biomarkers such as FGF-23 (intact: 88.7% and c-terminal: 93.4%), Klotho (95.3%; soluble form: 97.2%), tartrate-resistant acid phosphatase 5b (TRAP-5b) (92.5%), C-terminal telopeptide (CTX) (71.7%), and pro-collagen type 1 N-terminal pro-peptide (P1NP) (88.7%). As interesting data regarding Italian nephrologists' behavior to start treatment of secondary hyperparathyroidism (sHPT), the majority of clinicians used KDOQI guidelines (n = 55, 51.9%). In contrast, only 40 nephrologists (37.7%) relied on KDIGO guidelines, which recommended referring to values of PTH between two and nine times the upper limit of the normal range.

Conclusion

Results point out a marked heterogeneity in the management of CKD-MBD by clinicians as well as a suboptimal implementation of guidelines in Italian clinical practice.

MO909: Dialysis After Contrast Agent Administration in Patients on Chronic Haemodialysis: It is a Common Clinical Practice?

BACKGROUND AND AIMS

Though the current dialysis population is characterized by a better survival, there is a greater burden of cardiovascular comorbidities. These two factors together expose patients to a greater number of diagnostic and therapeutic contrast tests.

The European Society of Urogenital Radiology (ESUR) Guidelines on Contrast Agents 10.0 report that there is no need for urgent dialysis after intravascular iodinated contrast agent administration based on the results of the only study that addressed this problem, conducted in 10 patients by Younathan CM and published in the American Journal of Roentgenology in 1994. As far as the use of gadolinium contrast agent in dialysis patients, the recommendation is to try to perform the contrast agent injection prior to and close to the haemodialysis session, and an extra haemodialysis session to remove the contrast agent as soon as possible after it has been administered is recommended.

It is now a well-known phenomenon that when there are low-level recommendations, the behaviour of nephrologists is not homogeneous.

METHOD

We have created a very simple survey (only 10 questions) to explore the behaviour of Italian nephrologists with respect to the administration of contrast agents in dialysis patients. The main information we wanted to obtain concerned the attitude towards the need for a dialysis session after the administration of a contrast agent (iodate or gadolinium), the timing respect to the contrast examination and the duration of the dialysis session.

A total of 50 Italian nephrologists of 50 dialysis centres, respectively, responded to the questionnaire. The average number of chronic dialysis patients treated per single centre was 94 (median 80, interquartile range 46–135), meaning that these are representative of a population of at least 5000 haemodialysis patients.

RESULTS

After intravascular iodinated contrast agent, according to the ESUR guidelines 9 nephrologists (18%) do not perform an additional dialysis, while 34 nephrologists ( 68%) carry out an additional dialysis session (or organize the contrast examination to coincide with the scheduled dialysis session) (Fig. 1). A total of 32 nephrologists (64%) perform a specific dialysis session after magnetic resonance with gadolinium, as indicated in the ESUR guidelines (Fig. 2). In both cases (iodinated contrast agent or gadolinium), 28 nephrologists (56%) schedule the dialysis session within 4 h of the contrast examination (at least 2 h of treatment or complete dialysis session if possible).

Remarkably, 10 nephrologists (20%) do not organize a specific dialysis section after MR with gadolinium (Fig. 2).

CONCLUSION

Our data confirm that in Italy, the majority of nephrologists still carry out an additional dialysis session after the administration of an iodinated contrast agent to avoid the potential risk of delay and adverse effects (intravascular volume expansion, pulmonary edema, depression of myocardial contractility and arrhythmias). Haemodialysis is an expensive procedure, in particular when performed as a nonscheduled emergent treatment at odd hours of the day or night. Further studies are needed to clarify this controversial point.

Time for Revival of Bone Biopsy with Histomorphometric Analysis in Chronic Kidney Disease (CKD): Moving from Skepticism to Pragmatism

Bone Biopsy (BB) with histomorphometric analysis still represents the gold standard for the diagnosis and classification of different forms of renal osteodystrophy. Bone biopsy is the only technique able to provide comprehensive information on all bone parameters, measuring static and dynamic parameters of turnover, cortical and trabecular microarchitecture, and mineralization defects. In nephrological practice, bone biopsy yields relevant indications to support therapeutic choices in CKD, heavily impacting the management and prognosis of uremic patients. Unfortunately, the use of bone biopsy has decreased; a lack of expertise in performing and interpreting, perceived procedure invasiveness and pain, and reimbursement issues have all contributed to this decline. Nevertheless, both bone biomarkers and instrumental images cannot be considered reliable surrogates for histological findings, being insufficiently accurate to properly evaluate underlying mineral and bone disorders. This is a multidisciplinary position paper from the Nephrology and Osteoporosis Italian Scientific Societies with the purpose of restating the role of bone biopsy in CKD patient management and of providing strong solutions to allow diffusion of this technique in Italy, but potentially also in other countries. The Italian approach through the optimization and standardization of bone biopsy procedure, the construction of the Italian Hub and Spoke network, and a request for adjustment and national homogenization of reimbursement to the Italian Health Ministry has led the way to implement bone biopsy and to improve CKD patient management and prognosis.

The Role of Vitamin K in CKD-MBD

PURPOSE OF REVIEW

We describe the mechanism of action of vitamin K, and its implication in cardiovascular disease, bone fractures, and inflammation to underline its protective role, especially in chronic kidney disease (CKD).

RECENT FINDINGS

Vitamin K acts as a coenzyme of y-glutamyl carboxylase, transforming undercarboxylated in carboxylated vitamin K-dependent proteins. Furthermore, through the binding of the nuclear steroid and xenobiotic receptor, it activates the expression of genes that encode proteins involved in the maintenance of bone quality and bone remodeling. There are three main types of K vitamers: phylloquinone, menaquinones, and menadione. CKD patients, for several conditions typical of the disease, are characterized by lower levels of vitamin K than the general populations, with a resulting higher prevalence of bone fractures, vascular calcifications, and mortality. Therefore, the definition of vitamin K dosage is an important issue, potentially leading to reduced bone fractures and improved vascular calcifications in the general population and CKD patients.

Oral Calcitriol Use, Vertebral Fractures, and Vitamin K in Hemodialysis Patients: A Cross-Sectional Study

Fractures and vascular calcifications (VCs) are common in patients with chronic kidney disease (CKD). They are related to abnormalities in vitamin D metabolism, calcium, phosphorus, parathyroid hormone, and fibroblast growth factor 23 (FGF23)/Klotho that occur with CKD. Impaired vitamin D metabolism and abnormal levels of calcium, phosphate, parathyroid hormone (PTH), and FGF23/Klotho drive bone and vascular changes in CKD. It is unclear if oral calcitriol safely mitigates fracture risk without increasing the burden of calcifications. Therefore, we investigated whether treatment with calcitriol affected the prevalence of fractures and VC progression in hemodialysis (HD) patients. This report is a secondary analysis of the Vitamin K Italian (VIKI) study, a cross-sectional study involving 387 HD patients. We assessed vitamin 25(OH)D, alkaline phosphatase, PTH, calcium, phosphate, osteocalcin or bone Gla protein, matrix Gla protein, and vitamin K levels. Vertebral fractures (VFs) and VCs were determined by spine radiograph. A reduction of >20% of vertebral body height was considered a VF. VCs were quantified by the length of calcific lesions along the arteries. The patients treated with oral calcitriol were 177 of 387 patients (45.7%). The prevalence of VF was lower in patients receiving oral calcitriol than in those untreated (48.6% versus 61.0%, p = 0.015), whereas the presence of aortic and iliac calcifications was similar (aortic: 81.9% versus 79.5%, respectively, p = 0.552; iliac: 52.0% and 59.5%, respectively, p = 0.167). In multivariable logistic regression analysis, oral calcitriol was associated with a 40.2% reduced odds of fracture (OR 0.598; 95% confidence interval [CI], 0.363-0.985; p = 0.043). In conclusion, we found a significant association between oral calcitriol and lower VF in HD patients without an increase in the burden of VC. Further prospective and interventional studies are needed to confirm these findings. © 2021 American Society for Bone and Mineral Research (ASBMR).

The Vessels-Bone Axis: Iliac Artery Calcifications, Vertebral Fractures and Vitamin K from VIKI Study

Vascular calcification and fragility fractures are associated with high morbidity and mortality, especially in end-stage renal disease. We evaluated the relationship of iliac arteries calcifications (IACs) and abdominal aortic calcifications (AACs) with the risk for vertebral fractures (VFs) in hemodialysis patients. The VIKI study was a multicenter cross-sectional study involving 387 hemodialysis patients. The biochemical data included bone health markers, such as vitamin K levels, vitamin K-dependent proteins, vitamin 25(OH)D, alkaline phosphatase, parathormone, calcium, and phosphate. VF, IACs and AACs was determined through standardized spine radiograms. VF was defined as >20% reduction of vertebral body height, and VC were quantified by measuring the length of calcium deposits along the arteries. The prevalence of IACs and AACs were 56.1% and 80.6%, respectively. After adjusting for confounding variables, the presence of IACs was associated with 73% higher odds of VF (p = 0.028), whereas we found no association (p = 0.294) for AACs. IACs were associated with VF irrespective of calcification severity. Patients with IACs had lower levels of vitamin K2 and menaquinone 7 (0.99 vs. 1.15 ng/mL; p = 0.003), and this deficiency became greater with adjustment for triglycerides (0.57 vs. 0.87 ng/mL; p < 0.001). IACs, regardless of their extent, are a clinically relevant risk factor for VFs. The association is enhanced by adjusting for vitamin K, a main player in bone and vascular health. To our knowledge these results are the first in the literature. Prospective studies are needed to confirm these findings both in chronic kidney disease and in the general population.

MO798ORAL CALCITRIOL USE, VERTEBRAL FRACTURES AND VASCULAR CALCIFICATION IN HEMODIALYSIS PATIENTS: RESULTS FROM VITAMIN K ITALIAN (VIKI) STUDY

Background and Aims

In patients with Chronic Kidney Disease (CKD) mineral, bone, and calcific cardiovascular abnormalities are associated to adverse clinical outcomes, including fractures, cardiovascular events and mortality. Vitamin D hormonal system along with alteration levels that occur in calcium, phosphate, PTH, FGF23/Klotho are the main responsible of the bone and vascular metabolism changes, particularly in hemodialysis (HD) patients that experienced the very negative clinical consequences (decreased bone mass, increased fragility fractures and vascular calcification). In the setting of a comparative effectiveness study, we investigated the effect of oral calcitriol on fractures in HD patients taking into account a series of potential confounders.

Method

We conducted a secondary analysis of the VIKI database, a cross-sectional study involving 387 HD patients from 18 Italian dialysis centers. Routine biochemistry and bone biochemical markers such as vitamin K levels, VKDPs, vitamin 25(OH)D, ALP, PTH, Ca, P, osteocalcin (BGP), Matrix Gla Protein (MGP) were assessed. The presence of Vertebral Fractures (VF) and Vascular Calcification (VC) was determined through spine radiograph. Reduction of &gt;20% of vertebral body height was considered a VF. The severity of the vertebral fractures was estimated as mild, moderate and severe (reduction: 20-25%, 25-40% or &gt;40%, respectively). VC were quantified by measuring the length of calcific deposits along the arteries (mild 0,1-5 cm, moderate 5,1-10 cm and severe &gt;10 cm).

Results

177 out 387 patients (45.7%) were treated with oral calcitriol. Oral calcitriol-treated and untreated patients did not differ as for Ca, P, PTH, Albumin, BGP, MGP, and ALP. The prevalence of VF was significantly lower in patients receiving oral calcitriol than in those untreated (48.6% vs 61%, P=0.015), whereas the presence of aortic and iliac calcifications was similar between the two groups (aortic: 81.9% vs 79.5% respectively, P=0.552; iliac: 52.0% and 59.5%, P=0.167). No significant between-groups differences were observed in terms of calcification severity. In a multivariable logistic regression analysis, after adjustment for all potential confounders, oral calcitriol was associated with a marked reduction (-40.2%) of the odds of fractures (OR: 0.598, 95% CI: 0.363-0.985, P=0.043) (see Table).

Conclusion

A significant association was found between oral calcitriol and lower VF rate in HD patients. Such an effect remained significant also after data adjustment for a large series of potential confounders. Further prospective and interventional studies are needed to confirm these findings.

Sevelamer Use, Vitamin K Levels, Vascular Calcifications, and Vertebral Fractures in Hemodialysis Patients: Results from the VIKI Study

Hyperphosphatemia is a risk factor for vascular calcifications (VCs), which are part of the chronic kidney disease-mineral and bone disorders (CKD-MBD). Vitamin K-dependent proteins such as matrix Gla protein (MGP) and bone Gla proteins (BGP, or osteocalcin) can inhibit VCs and regulate bone mineralization. In this analysis of the Vitamin K Italian (VIKI) study, the relationship between vitamin K status, vertebral fractures (VFs) and VCs in 387 hemodialysis (HD) patients with (N = 163; 42.1%) or without N = 224; 57.9%) sevelamer was evaluated. Levels of vitamin K vitamers K1 and K2 or menaquinones (MK; MK4-7), total and undercarboxylated (uc) forms for both BGP and MGP were determined. Although no differences in clinical characteristics were noted, lower levels of MK4 (0.45 versus 0.6 ng/mL, p = .01) and a greater MK4 deficiency was observed in sevelamer-treated patients (13.5% versus 5.4%, p = .005). Multivariate logistic regression revealed that MK4 deficiency was associated with sevelamer use (odds ratio [OR] = 2.64, 95% confidence interval [CI] 1.25-5.58, p = .011) and aortic calcification (OR = 8.04, 95% CI 1.07-60.26, p = .04). In the same logistic model, sevelamer amplified the effect of total BGP levels on the odds of VFs in patients with total BGP <150 μg/L compared with those with total BGP ≥150 μg/L (OR = 3.15, 95% CI 1.46-6.76, p = .003). In contrast, there was no such effect in those untreated (total BGP <150 μg/L versus total BGP ≥150 μg/L: OR = 1.21, 95% CI 0.66-2.23, p = .54]; p = .049 for effect modification by sevelamer). Sevelamer may interfere with MK4 levels in HD patients and interact with low BGP levels to increase bone fractures in CKD patients. © 2020 American Society for Bone and Mineral Research (ASBMR).

P1485SEVELAMER USE IS ASSOCIATED WITH DECREASED VITAMIN K LEVELS IN HEMODIALYSIS PATIENTS: RESULTS FROM VITAMIN K ITALIAN (VIKI) STUDY

Background and Aims

Sevelamer (S) is a phosphate binding drug used to treat hyperphosphatemia in patients with CKD. Our aim was to evaluate the hypothesis that the use of (S) could interfere with Vitamin K absorption in hemodialysis (HD) patients of VIKI study.

Method

We tested this hypothesis in VIKI, a cross-sectional study of 387 hemodialysis patients, we established the prevalence of vitamin K deficiency and to assessed the relationship between vitamin K status, vertebral fractures, vascular calcification. We determined serum concentrations of vitamin 25(OH)D; alkaline phosphatase (ALP); vitamers K1, MK4, MK5, MK6, MK7; osteocalcin (BGP) and Matrix Gla Protein (MGP). We highlighted that MK4 deficiency was the strongest predictor of aortic calcification (OR, 2.82; 95% CI, 1.14–7.01) while vitamin K1 deficiency was the strongest predictor of vertebral fractures fractures (OR: 2.94; 95% CI, 1.38–6.26).

Results

163 of 387 patients (42.1%) were treated with Sevelamer. There were no differences in levels of 25(OH)D, K1, MK5, MK6 and MK7 among patients treated with and without Sevelamer. Remarkably, the prevalence of MK4 deficiency was higher in Sevelamer treated patients (13.5% vs 5.4%, p=0.005). Sevelamer treated patients also had higher median levels of ALK (89 UI/L vs 77.5 UI/L, p=0.001) and total BGP (210 mcg/L vs 152 mcg/L, p=0.002) and lower median levels of total MGP (16.4 nmol/L vs 20.3 nmol/L, p=0.037) (Table 1 and Figure 1). In multivariable logistic regression, the odds ratio of MK4 deficiency (dependent variable) in patients treated with compared to without Sevelamer was ∼3-fold higher (OR: 2.64, 95% CI: 1.25-5.58, p=0.011) after adjustment for confounders of Vitamin K levels, including older age, previous myocardial infarction, type of HD, ALP, PTH, MGP, BGP, cholesterol and albumin.

Conclusion

These data support the hypothesis that Sevelamer could interfere with MK4 absorption in HD patients. Longitudinal interventional studies are needed to prove the causal nature of these associations.

Overweight-obesity is associated with decreased vitamin K2 levels in hemodialysis patients

OBJECTIVES

Obesity is an important risk factor for morbidity and mortality. Vitamin K2 is involved in the production of bone and matrix amino acid g-carboxy-glutamic acid (Gla) proteins (vitamin K-dependent proteins [VKDPs]), regulating bone and vascular calcification (VC). Bone Gla protein (BGP) is involved both in bone mineralization and VCs. We assessed the relationships between vitamin K levels and body mass index (BMI) according to the hypothesis that the impact of BMI on mortality is partly driven by low vitamin K levels.

METHODS

The Vitamin K Italian (VIKI) study included 387 hemodialysis patients from 18 dialysis centers in Italy. We determined plasma levels of bone markers: vitamin K levels, VKDPs, vitamin 25(OH)D, alkaline phosphatase (ALP), parathyroid hormone (PTH), calcium (Ca), phosphorus (P) and routine biochemistry. BMI was classified into the following categories: underweight (BMI < 18.5 kg/m²), normal weight (18.5 ≤ BMI < 25 kg/m²), overweight (25 ≤ BMI < 30 kg/m²) and obese (BMI ≥ 30 kg/m²).

RESULTS

45.2% of patients were overweight or obese. Stratification by BMI demonstrated lower median menaquinone-7 (MK7)/triglycerides levels in obese patients (0.42 ng/mg [0.19, 0.87], p = 0.005). BGP levels were lower in overweight and obese patients (152 mcg/L [83.2, 251] and 104 mcg/L [62.7, 230], p = <0.001). Furthermore, there was an inverse correlation between MK7/triglycerides levels and BMI (regression coefficient β = -0.159; p = 0.003). In multiple linear regression, there was an inverse relationship between BGP levels and BMI (β = - 0.119; p = 0.012).

CONCLUSIONS

These data are the first to report an inverse relationship between Vitamin K2 levels and BMI in hemodialysis patients. Further studies are needed to confirm these findings and to determine if lower levels of Vitamin K are related to greater morbidity and mortality in this at-risk population.

Clinical Management of Chronic Kidney Disease Patients in Italy: Results from the IRIDE Study

BACKGROUND

Lack of adequate management of chronic kidney disease (CKD) often results in delayed diagnosis and inadequate treatment. This study assessed the clinical management and outcome of stages 1-5 CKD patients.

METHODS

Patients were prospectively followed for 3 years in 25 nephrology centers across Italy. Clinical characteristics were measured at baseline and every 6 months. Outcome measures included CKD staging, presence of comorbidities, treatment, mineral bone disorder (MBD) parameters, and patient outcomes.

RESULTS

Of 884 enrolled patients (59.7% males, aged 66.2 ± 14.6 years), 587 (66.4%) completed the study. The majority of patients were referred by a general practitioner (44.7%) and had stage 3 or 4 CKD (40.9 and 23.8% respectively). Data reveal that 91.3% of patients had at least 1 concomitant disease, most frequently hypertension (80.1%) and dyslipidemia (42.5%); 94.6% of patients were receiving cardiovascular medication and 52.6% were receiving lipid-lowering medication. Approximately 40% of patients had proteinuria and intact parathyroid hormone levels outside the normal range. As expected, stages 4 and 5 CKD patients had a higher prevalence of proteinuria (68 and 74%), MBD (59 and 88%) and anemia (28 and 73%), as well as a higher risk of hospitalization (34.3 and 51.9%) and need for dialysis (69.5 and 70%). The overall probability of survival over 36 months was 90.6%.

CONCLUSIONS

This is the first Italian prospective study performed with a large cohort of CKD patients over a 3-year period. Considering the multifactorial burden of diseases associated with CKD patients, the need for greater attention to CKD and related disorders is paramount.

[Update 2017 of the KDIGO guidelines on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). What are the real changes?]

Guidelines for the assessment, diagnosis and therapy of the alterations that characterize the CKD-MBD are an important support in the clinical practice of the nephrologist. Compared to the KDIGO guidelines published in 2009, the 2017 update made changes on some topics on which there was previously no strong evidence both in terms of diagnosis and therapy. The recommendations include the diagnosis of bone anomalies in CKD-MBD and the treatment of mineral metabolism abnormalities with particular regard to hyperphosphataemia, calcium levels, secondary hyperparathyroidism and anti-resorptive therapies. The Italian Study Group on Mineral Metabolism, in reviewing the 2017 recommendations, aimed to assess the weight of the evidence that led to this update. In fact, on some topics there has not been a substantial difference on the degree of evidence compared to the previous guidelines. The Italian Study Group emphasizes the points that may still reserve critical issues, including interpretation, and invites an evaluation that is articulated and personalized for each patient.

[Fragility fracture in the Chronic Kidney Disease (CKD)]

Fragility fractures (FF) are common in patients with chronic kidney disease (CKD), and they occur at a younger age and with a higher frequency than in the general population, producing significant morbidity, mortality and healthcare costs. The pathogenic mechanisms underlying FF in CKD patients have not been completely understood. Behind CKD-MBD, the uremic toxicity should play a role in their pathogenesis, by affecting bone quality (uremic osteoporosis). There are very few prospective studies investigating risk factors for fragility fractures in CKD patients, and available algorithms for fracture risk prediction (FRAX and DeFRA) have never considered CKD. The diagnosis of vertebral fractures (FV), under-diagnosed in CKD patients as well as in general population, should be performed by Quantitative Vertebral Morphometry (QVM) both with DXA or Spine (D4-L5) x-Ray. A recent KDIGO review has qualified the measurement of the Bone Mineral Density by DXA as a predictive tool for fracture risk assessment in patients with stage G3a-G5D. Furthermore, the Trabecular Bone Score (TBS, software applied to DXA) allows the bone quality evaluation as well as the fracture risk prediction. Other techniques, such as Quantitative Computerized Tomography (QCT), especially High Resolution-peripheral QCT (HR-pQCT), have been shown to be useful, although expensive. Finally, some bone biomarkers (PTH and BAP) demonstrated to be informative for the definition of fracture risk in patients with CKD-MBD. In conclusion, there are several different tools and approaches that demonstrated to be useful for the identification of CKD patients at high risk of fracture, when these are appropriately performed and interpreted by expertise clinicians.

Vitamin K and bone

Vitamin K is mainly known as an agent involved in blood coagulation, maintaining the activity of coagulation factors in the liver. In addition, epidemiological studies suggested that a lack of vitamin K is associated with several diseases, including osteoporosis and vascular calcification. There are two main kinds of vitamin K: Phylloquinone (or PK) and Menaquinones (MKn), both act as co-enzyme of y-glutamyl carboxylase (GGCX) transforming under-carboxylated in carboxylated vitamin K dependent proteins, such as Bone Gla Protein (or Osteocalcin) and Matrix Gla Protein. Recently, Vitamin K was also identified as a ligand of the nuclear steroid and xenobiotic receptor (SXR) (in murine species Pregnane X Receptor: PXR), expressed in osteoblasts. The purpose of this literature review is to evaluate the protective role of Vitamin K in bone and vascular health.

Vitamins (A, C and E) and oxidative status of hemodialysis patients treated with HFR and HFR-Supra

BACKGROUND

Hemodiafiltration with on-line endogenous reinfusion (HFR) is an extracorporeal dialytic method that combines diffusion, convection and adsorption. HFR-Supra (HFR-S) is a second-generation system with increased convective permeability and adsorption capability. Previous studies suggested that HFR reduces oxidative stress compared to standard haemodialysis. The principal aim of the present study was to compare antioxidant vitamins behavior and oxidative status of hemodialysis patients treated with HFR and HFR-S.

METHODS

The study was designed as a multicenter, randomized, crossover trial. Forty-one patients were recruited from 19 dialysis centers and after a 4-month washout stabilization period in on-line hemodiafiltration (ol-HDF), each patient was randomized to a sequence of treatments (HFR-S followed by HFR or viceversa) with each treatment applied over 6 months. Plasma levels of Advanced Oxidation Protein Products, Total Antioxidant Status, vitamins C, A and E and their ligands (Retinol Binding Protein and total lipids) were measured at baseline and at the end of each treatment period.

RESULTS

Results show that the higher convective permeability of HFR-S with respect to HFR did not produce additional beneficial effects on the patients' oxidative status, a slight decrease of both Vitamin A and Retinol Binding Protein being the only difference registered in the long-term. However, as compared to ol-HDF, both the re-infusive techniques allowed to reduce the intradialytic loss of Vitamin C and, in the long-term, improve the patients' oxidative status and increase Retinol Binding Protein plasma values. No significant differences were found between the Vitamin C concentration of pre- and post cartridge UF neither in HFR-S nor in HFR showing that the sorbent resin does not adsorb Vitamin C.

CONCLUSION

HFR-S and HFR are almost equivalent in term of impact on antioxidant vitamins and oxidative status of hemodialysis patients. Nonetheless, as compared to ol-HDF, both treatments produced a sensible sparing of Vitamin C and may represent a new approach for reducing oxidative stress and related complications in dialysis patients. Long-term effects of re-infusive treatments on patients' cardiovascular morbidity and mortality need to be evaluated.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT01492491 , retrospectively registered in 10 December 2011.

Interaction between parathyroid hormone and the Charlson comorbidity index on survival of incident haemodialysis patients

BACKGROUND

Haemodialysis patients are ageing and have with a high rate of comorbidities. The impact of this novel clinical setting on intact parathyroid hormone (iPTH) is not well established.

METHODS

For this observational, prospective multicentre cohort study, incident haemodialysis patients were recruited in 40 Italian centres and followed up for a mean period of 18 +/- 6.7 months. Clinical characteristics and biochemistry were recorded at baseline. Comorbid conditions were scored by the Charlson comorbidity index (CCI).

RESULTS

Data of 411 patients (mean age: 66.5 +/- 14.8 years; 17.3% >80 years old) were recorded. The mean CCI was 4.17 +/- 2.8. In patients with CCI >0, an inverse correlation was observed between CCI (excluding age) and iPTH (P = 0.00002). Independently of CCI, patients with iPTH <150 pg/ml had 76% as high as the risk of all-cause mortality. After multivariable adjustment, the combination of the first tertile of iPTH with second and third tertiles of CCI was significantly associated with all-cause mortality (RR = 3.83, P = 0.02; RR = 3.79, P = 0.01, respectively).

CONCLUSIONS

Incident haemodialysis patients suffer from a high rate of clinical complications. In these patients, low iPTH and high CCI are often associated and very likely responsible for an adverse outcome.

[The treatment of osteodystrophy in dialyzed uremic patients: results of the first Sardinian audit]

BACKGROUND

Hyperphosphatemia in the uremic patient undergoing dialysis causes and makes the secondary hyperpharatyroidism progress. Nowadays it has a very important role in predicting mortality. The aim of the study was to assess by "Audit" to analyse adequacy of the Sardinian dialytic patients with reference to the optimal objective of the national and international guidelines.

PATIENTS AND METHODS

The questionnaire of the audit was composed of 11 questions about the percentage distribution of: calcium in the dialysate, values of phosphoremia), Ca x P product, patients treated with vitamin D taking one or more phosphate binders, average dose, spKt/V > or = 1.2, serum aluminium, parathiroidectomy.

RESULTS

We examined 1274 dialysis patients (93% on hemodialysis and 7% in CAPD) in 26 dialytic centers in our region (age 63.8 anni +/- 32.4; dialytic age 5.15 +/- 5.06. Phosphorus ranges (mg/dL) P < 5.5: 61.3 +/- 23%; between 5.5 e 6.5: 28.2 +/- 17.7%; and P > 6.5: 10.4 +/- 7.7%; Ca x P (<60): 77.8% +/- 16.6%; between 60-70: 16.8 +/- 13.4%; > 70: 4.99 +/- 4.7%. The more prescribed dialysate calcium was 1.5 mmol/L in HD (58.8%) HF (60.6%), HDF (51.6%) and CAPD (5.6%). PTH levels were: 31.1% (<120); 29.5% (120-250); 21.1% (250-450); 8% (450-600); 10.3% (>600). Patients on vitamin D: os daily 23.04 +/- 28%; post-dialysis boluses: os 32.6 +/- 28, i.v. 10.6 +/- 9%; no therapy 32.7 +/- 22.7%. The percentage use of phosphorus binders: 48.5% calcium carbonate (2.9 g/d); 7.12% calcium acetate (1.34 g/d); 13.5% sevelamer (2.79 g/d); 10% total aluminium based (0.62 g/d). The aluminium is dosed in 11/26 dialysis units (32.3% of the population); 2.3% +/- 0.9% of patients having Aluminium > 30 mcg/L. The dialytic patients have a Kt/V > or = 1.2: 80.1 +/- 19%. Parathyroidectomy incidences 1.8%.

CONCLUSIONS

The data show good control of the average phosporous, there is a worrying percentage of patients with PTH values compatible with hypodynamic bone condition, lower and therefore safer calcium levels in the dialysate, poor aluminium control and low incidence of parathyroidectomy. In our experience the audit is a good way to verify and to correct the therapeutic choice in uremic osteodistrophy.

[Are convective treatments equivalent to the traditional ones? The Hemo Study and beyond (review)]

Dialysis treatments have allowed 'terminal patients' to live for years and years. However, life expectancy and quality are still consistently reduced in renal dialysis patients. Consequently, all efforts to device alternative treatments to the conventional ones are highly justified. Recently, the Hemo Study showed that neither the use of high flux membranes, nor the increase of the dialysis dose above the conventional, were capable to reduce significantly patient's mortality and morbidity, although 8% reduction of the risk of death was seen in patients treated with high flux vs. patients treated with low-flux dialysis. A relevant question is if convective treatments may offer an overprotection from morbidity and mortality, in comparison with low flux and high flux treatments. Data from the Registro Lombardo di Nefrologia e Trapianto published in 2000 showed a trend toward a better survival (RR= 90) and a significantly better protection from tunnel carpal syndrome (RR= 0.58; p= 0.03) in patients treated with convective treatments (hemofiltration and/or hemodiafiltration) vs. patients treated with diffusive dialysis. Except than a better cardiovascular stability observed on hemofiltration and an higher beta2-microglobuline clearance given by online hemofiltration and hemodiafiltration, evident clinical benefits of convective treatments, over the conventional high flux treatments, are not yet clearly demonstrated. Notwithstanding that, online convective treatments, that are performed with high flux compatible membranes and high technology machines, producing high quality water, offer at the moment the best bases for the improvement of clinical results of dialysis, especially in some category of patients.

[Hyperparathyroidism resulting from chronic renal insufficiency. Diagnosis and therapy]

Twenty-seven patients, eighteen females and nine males, with chronic renal failure and secondary hyperparathyroidism, were treated by subtotal parathyroidectomy. Bone pain, in 24 patients, hypercalcemia in 2 and severe pruritus in 1 were the main indications to surgery. Result evaluation was possible in twenty four patients. Bone pain disappeared or was reduced in 20/22 patients. Serum alkaline phosphatase and PTH returned to normal in 21/24 patients. There patients had persistent hyperparathyroidism because of inadequate surgical exploration. Another group of seven patients with secondary hyperparathyroidism recalcitant to medical therapy or relapsing after subtotal parathyroidectomy was treated with calcitriol ev. After nine months of follow-up PTH and alkaline phosphatase serum levels were reduced to normal value in all patients.

[Psoriatic arthritis: considerations on recent studies: serum beta 2 microglobulin and circulating T-gamma lymphocytes]

The results of two recent studies of our group have been reported. They regard two immunological parameters of psoriatic arthritis: the proportions of T gamma lymphocytes in peripheral blood and the beta 2 microglobulin in the serum. The data obtained in psoriatic arthritis patients have been compared to those found in normal controls and in rheumatoid arthritis patients. T gamma mean values in psoriatic arthritis were significantly lower than those present in healthy subjects and in rheumatoid patients. These last patients showed beta 2 microglobulin mean values significantly higher than those observed in normal controls and in psoriatic arthritis patients. Conversely, the mean of beta 2 microglobulin levels in psoriatic arthritis has been found to be similar to that observed in normal controls, but a superimposition in the range of individual values of these two groups with the concentrations determined in rheumatoid subjects has been found. These results seem to be of interest in relation to the immunopathogenetic mechanism of psoriatic arthritis, but are of little help in the clinical differentiation of the two rheumatological affections considered.

T gamma lymphocytes of peripheral blood and synovial fluid in rheumatoid arthritis: quantitative determination and qualitative analysis

The distribution of T gamma lymphocytes in the peripheral blood of one group of rheumatoid patients and in the synovial fluid in a second group was determined. The results were compared to those found for peripheral blood (PB) lymphocytes of normal subjects and for synovial fluid lymphocytes of osteoarthrosis and meniscitis patients. Besides recording percentage and absolute number, we also used cytofluorographic analysis to determine individual capacity of PB T gamma cells to bind heat-aggregated IgG (agg-IgG). The following results were found: 1) there is no significant difference between the percentage and absolute number of PB T gamma lymphocytes of rheumatoid arthritis (RA) patients and those of controls, 2) individual RA PB T gamma cells had a greater number and/or avidity of Fc receptor for IgG than those cells of controls, and 3) the percentage of RA T gamma lymphocytes in synovial fluid, revealed by IgG-EA ox rosetting, is significantly lower than that found in control patients. The factors that may determine a similar lymphocyte picture in RA are discussed.

Characterization of human T lymphocyte subpopulations (TG and T non G): cytologic examination and cytographic analysis

Two T lymphocyte subpopulations were separated with an immunological method. In fact recently two T cell subsets with receptors for the Fc of IgM (TM) and of IgG (TG) respectively have been described. We have specifically separated TG and T non G lymphocytes by the rosetting technique. Cytological examination was performed on the two cell fractions: the results are in agreement with that already reported. Cytographic analysis was also carried out confirming the cytologic results. The possible practical implications of these acquisitions and those already applied are discussed.