Dialysis-related amyloidosis: late finding or hidden epidemic?

Renal Replacement Modality Affects Uremic Toxins and Oxidative Stress

Nowadays, the high prevalence of kidney diseases and their related complications, including endothelial dysfunction and cardiovascular disease, represents one of the leading causes of death in patients with chronic kidney diseases. Renal failure leads to accumulation of uremic toxins, which are the main cause of oxidative stress development. The renal replacement therapy appears to be the best way to lower uremic toxin levels in patients with end-stage renal disease and reduce oxidative stress. At this moment, despite the increasing number of recognized toxins and their mechanisms of action, it is impossible to determine which of them are the most important and which cause the greatest complications. There are many different types of renal replacement therapy, but the best treatment has not been identified yet. Patients treated with diffusion methods have satisfactory clearance of small molecules, but the clearance of medium molecules appears to be insufficient, but treatment with convection methods cleans medium molecules better than small molecules. Hence, there is an urgent need of new more validated, appropriate, and reliable information not only on toxins and their role in metabolic disorders, including oxidative stress, but also on the best artificial renal replacement therapy to reduce complications and prolong the life of patients with chronic kidney disease.

Peptides in Plasma, Urine, and Dialysate: Toward Unravelling Renal Peptide Handling

PURPOSE

The peptidomes of spent hemodialysate, urine, and plasma are investigated, to shed light on peptide handling in the kidney.

EXPERIMENTAL DESIGN

Fifteen plasma, 15 urine, and 13 spent hemodialysate samples are collected from age- and sex-matched subjects with chronic kidney disease. Peptide identification and quantification are performed with capillary electrophoresis-coupled mass spectrometry.

RESULTS

A total of 6278 urinary peptides, 1743 plasma peptides, and 1727 peptides from spent hemodialysate are detected. Of these, sequences can be assigned to 1580, 419, and 352 peptides, respectively. A strong correlation in peptide abundance between urine and spent hemodialysate (p = 3 × 10-21 , Rho = 0.52), a moderately strong correlation between spent hemodialysate and plasma (p = 4.5 × 10-5 , Rho = 0.30), and no significant correlation between urine and plasma (p = 0.11, Rho = 0.094) are found. Collagen and fibrinogen alpha peptides are highly abundant in all three body fluids. In spent hemodialysate, thymosin ß4 is one of the most abundant peptides, which is shown to be negatively associated with the estimated glomerular filtration rate (Rho = -0.39, p-value = 3.9 × 10-81 ).

CONCLUSION AND CLINICAL RELEVANCE

The correlation of peptide abundance in these three body fluids is lower than expected, supporting the hypothesis that tubular reabsorption has a major impact on urinary peptide content. Further investigation of thymosin ß4 in hemodialysis is thus warranted.

Beta-2 Microglobulin Amyloidosis: Past, Present, and Future

Almost half a century has elapsed since the first description of dialysis-related amyloidosis (DRA), a disorder caused by excessive accumulation of β-2 microglobulin (B2M). Within that period, substantial advances in RRT occurred. These improvements have led to a decrease in the incidence of DRA. In many countries, DRA is considered a "disappearing act" or complication. Although the prevalence of patients living with RRT increases, not all will have access to kidney transplantation. Consequently, the number of patients requiring interventions for treatment of DRA is postulated to increase. This postulate has been borne out in Japan, where the number of patients with ESKD requiring surgery for carpal tunnel continues to increase. Clinicians treating patients with ESKD have treatment options to improve B2M clearance; however, there is a need to identify ways to translate improved B2M clearance into improved quality of life for patients undergoing long-term dialysis.

Comparison of shoulder Magnetic Resonance Imaging findings between patients with stage 4 chronic kidney disease and hemodialysis patients with healthy controls

BACKGROUND

Shoulder involvement is frequently observed in chronic renal disease (CRD) and hemodialysis patients.

OBJECTIVE

Our aim is to compare shoulder Magnetic Resonance Imaging (MRI) findings of stage 4 CRD patients naive to dialysis, hemodialysis patients and healthy controls.

METHODS

Twenty hemodialysis patients with shoulder pain (Group 1), 30 hemodialysis patients without shoulder pain (Group 2), 20 patients with stage 4 CRD (Group 3) and 30 healthy controls (Group 4) were enrolled. Urea, creatinine and β2 microglobulin were measured. Thickness, homogeneity and integrity of rotator cuff and presence of effusion were examined by MRI.

RESULTS

Supraspinatus tendon was thicker in Group 1 compared to other groups, whereas infraspinatus tendon was thicker in Group 1 compared to Groups 2 and 4. Although all tendons thickness was higher in Group 3 than Group 4, there was no significant difference. Most effusion areas were present in Group 1, followed by Groups 2 and 3. There was a significant correlation between glomerular filtration rate and thickness of supraspinatus, infraspinatus tendons and between β2 microglobulin and thickness of infraspinatus, subscapularis tendons and total number of areas with effusion.

CONCLUSIONS

Increased shoulder tendon thickness and effusion were detected in symptomatic dialysis patients, while greater effusion areas were detected in asymptomatic dialysis patients and in stage 4 CRD patients who do not require dialysis compared to healthy controls.

Arm and hand function in hemodialysis patients. A cross sectional analytical study

Aims: To investigate the arm and hand function in hemodialysis patients.Methods: Upper limb function using validated questionnaires such as Disabilities of the Arm, Shoulder and Hand Questionnaire (DASH), Cochin and Boston were applied to 57 chronic renal failure patients on hemodialysis and 60 healthy controls. Epidemiological data, data on pain and paresthesia in the upper limb and handgrip strength were obtained.Results: The three questionnaires showed worse performance of upper limb function in chronic renal failure patients than controls: DASH questionnaire with P = 0.05; Cochin questionnaire with P = 0.0004 and Boston questionnaire with P = 0.03. The questionnaire scores were affected by presence of pain (P = 0.05 for DASH and < 0.0001 for Boston questionnaires) and paresthesia (DASH with P = 0.003; Cochin with P = 0.01 and Boston questionnaire with P < 0.0001). Handgripstrength was lower in hemodialysis patients when compared with controls (P = 0.02) but did not affect the performance of any of the studied questionnaires.Conclusions: Upper limb function is impaired in hemodialysis patients and the main associations found were with pain and paresthesia.

Amyloid Goiter in a Patient with Rheumatoid Arthritis and End-Stage Renal Disease

The association between amyloidosis and collagen vascular diseases, such as rheumatoid arthritis (RA) is well-documented. Amyloid goiter is an extremely rare pathologic condition caused by a massive amyloid infiltration of the thyroid tissue. Our patient had been diagnosed with RA 20 years ago and was on hemodialysis for 7 years. He was assessed for decreased appetite, dysphagia, and nausea during the hemodialysis. On physical examination, the thyroid was diffusely enlarged with multiple nodules. He was biochemically euthyroid. Ultrasound of the thyroid gland showed multinodular goiter. A total thyroidectomy was performed. Histopathological examination showed dilated follicles surrounded by abundant homogeneous substance that stained positive with Congo red. The patient was reported as amyloid goiter. Complaints of the patient improved after the surgery. In the literature, amyloid goiter with RA in a hemodialysis patient is very rare. Amyloid goiter should be considered if there is a rapid thyromegaly causing pressure symptoms in the background of any disease with chronic inflammation.

Collagen I Weakly Interacts with the β-Sheets of β2-Microglobulin and Enhances Conformational Exchange To Induce Amyloid Formation

Amyloidogenesis is significant in both protein function and pathology. Amyloid formation of folded, globular proteins is commonly initiated by partial or complete unfolding. However, how this unfolding event is triggered for proteins that are otherwise stable in their native environments is not well understood. The accumulation of the immunoglobulin protein β₂-microglobulin (β₂m) into amyloid plaques in the joints of long-term hemodialysis patients is the hallmark of dialysis-related amyloidosis (DRA). While β₂m does not form amyloid unassisted near neutral pH in vitro, the localization of β₂m deposits to joint spaces suggests a role for the local extracellular matrix (ECM) proteins, specifically collagens, in promoting amyloid formation. Indeed, collagen and other ECM components have been observed to facilitate β₂m amyloid formation, but the large size and anisotropy of the complex, combined with the low affinity of these interactions, have limited atomic-level elucidation of the amyloid-promoting mechanism(s) by these molecules. Using solution NMR approaches that uniquely probe weak interactions in large molecular weight complexes, we are able to map the binding interfaces on β₂m for collagen I and detect collagen I-induced μs–ms time-scale dynamics in the β₂m backbone. By combining solution NMR relaxation methods and ¹⁵N-dark-state exchange saturation transfer experiments, we propose a model in which weak, multimodal collagen I−β₂m interactions promote exchange with a minor population of amyloid-competent species to induce fibrillogenesis. The results portray the intimate role of the environment in switching an innocuous protein into an amyloid-competent state, rationalizing the localization of amyloid deposits in DRA.

Chronic intestinal pseudo-obstruction due to β2microglobulin-amyloidosis in a patient on high-flux haemodialysis

Dialysis-related amyloidosis (DRA) or β2microglobulin (β2m)-amyloidosis is a disorder caused by the inability to clear a protein called β2m in patients with chronic kidney disease. It results in deposition of β2m as amyloid fibrils, most commonly in bones and joints. Infrequently, visceral organs may be involved. With modern high-flux haemodialysis, DRA has become a rare disease, yet it may occur. We present a case of DRA in an 86-year-old woman. This case is particularly notable for its rare presentation as chronic intestinal pseudo-obstruction. It is of paramount importance to recognise this entity in order to reduce delay in treatment and avoid patients being frustrated not getting a diagnosis.

An Organ System-Based Approach to Differential Diagnosis of Amyloid Type in Surgical Pathology

CONTEXT.—

Amyloidosis is an uncommon but important entity. A protein-based classification of amyloidosis defines the underlying disease process, directing clinical management and providing prognostic information. However, in routine surgical pathology there often is no attempt to classify amyloid other than staining to determine light chain-associated amyloidosis. Systemic and localized amyloidosis vary with respect to frequency of organ involvement by different amyloid types, and most amyloid proteins have commercial antibodies available for identification.

OBJECTIVE.—

To provide a guide for the likelihood of amyloid type by organ system.

DATA SOURCES.—

Literature review based on PubMed searches containing the word amyloid, specifically addressing the prevalence and significance of amyloid proteins in each organ system other than the brain, and the authors' practice experience.

CONCLUSIONS.—

In patients with amyloidosis, determination of the responsible protein is critical for appropriate patient care. In large subspecialty practices and reference laboratories with experience in using and analyzing relevant immunohistochemistry, most amyloid proteins can be identified with an organ-specific algorithm. Referring to an organ-based algorithm may be helpful in providing clinicians with a more specific differential diagnosis regarding amyloid type to help guide clinical evaluation and treatment. When the protein cannot be characterized, mass spectrometry can be performed to definitively classify the amyloid type.

Positron Emission Tomography Can Support the Diagnosis of Dialysis-Related Amyloidosis

BACKGROUND

The improvements in dialysis have not eliminated long-term problems, including dialysis-related amyloidosis (DRA), caused by Beta-2 microglobulin deposition. Several types of scintigraphy have been tested to detect DRA, none entered the clinical practice. Aim of the study was to assess the potential of PET-FDG scan in the diagnosis of DRA.

METHODS

Forty-six dialysis patients with at least one PET scan (72 scans) were selected out 162 patients treated in 2016-2018. Subjective global assessment (SGA), malnutrition inflammation score (A), Charlson Comorbidity Index (CCI), were assessed at time of scan; 218 age-matched cases with normal kidney function were selected as controls. PET scans were read in duplicate. Carpal tunnel syndrome was considered a proxy for DRA. A composite "amyloid score" score considered each dialysis year = 1 point; carpal tunnel-DRA = 5 points per site. Logistic regression, ROC curves and a prediction model were built.

RESULTS

The prevalence of positive PET was 43.5% in dialysis, 5% in controls (p < 0.0001). PET was positive in 14/15 (93.3%) scans in patients with carpal tunnel. PET sensitivity for detecting DRA was 95% (specificity 64%). Carpal tunnel was related to dialysis vintage and MIS. A positive PET scan was significantly associated with dialysis vintage, MIS and amyloid score. A prediction model to explain PET positivity combined clinical score and MIS, allowing for an AUC of 0.906 (CI: 0.813-0.962; p < 0.001).

CONCLUSIONS

PET-FDG may identify DRA, and may be useful in detecting cases in which inflammation favours B2M deposition. This finding, needing large-scale confirmation, could open new perspectives in the study of DRA.

Mid-Term Outcomes of Primary Hip Replacement in Patients with End-Stage Chronic Renal Disease

Purpose — to evaluate mid-term outcomes of primary hip replacement in patients with end-stage chronic renal disease and to develop an algorithm for selection of surgical tactics and perioperative treatment.

Materials and Methods. The authors evaluated outcomes of primary hip replacement in 45 patients receiving renal substitution therapy and 47 patients without chronic renal disease. Patients with end-stage chronic renal disease (CRD) were divided into two groups: group I included 30 (66.6%) patients receiving chronic hemodialysis (CH) and group II included 15 (33.4%) patients after renal transplantation (RT). Group III of 47 (51.1%) patients without any signs of CRD who underwent hip arthroplasty within relevant period of time was established to evaluate the effectiveness of primary hip replacement. Blood serum Ca2+ and P5+ levels as well as levels of parathyroid hormone (PTH) and 1.25-dihydroxyvitamin D were measured to determine the rate of calcium- phosphoric metabolism disturbance. Multi-spiral CT scans of hip joint were performed to identify bone mineral density and the mean Hounsfield (Hu) value was calculated for which the data was obtained from five various points on the proximal femur and acetabulum. Beta-2 microglobulin (B2M) blood test was performed to confirm amyloid bone disease.

Results. The authors did not observe statistically significant differences for arthroplasty outcomes in patients of group II and III. Patients receiving long-term hemodialysis demonstrated significantly lower parameters of Harris score and Barthel’s index of social adaptation after hip replacement as compared to groups II and III: patients of group I demonstrated outcomes improvement at 19.55%, in group II — at 13.03%, in group III — at 10.15% as compared to preoperative status. Decrease of 1.25-dihydroxyvitamin D below 20,0 mcg results in resorption of cancellous bone in proximal femur and acetabulum along with myopathy of gluteus muscles. Sharp increase of parathyroid hormone level (over 600 pcg/ml) was accompanied by inhibition of osteoblasts proliferation and differentiation resulting in substantial impairment of mineralization.

Conclusion. According to the algorithm suggested by the authors the key parameters that need to be evaluated in preoperative period are parathyroid hormone (PTH) and 1.25-dihydroxyvitamin D. Five-fold increase of PTH (>600 pcg/ml) demands parathyroidectomy as the first stage of treatment to decrease risk of early aseptic loosening of hip prosthesis and development of periprosthetic fracture.

Extracellular matrix components modulate different stages in β2-microglobulin amyloid formation

Amyloid deposition of WT human β2-microglobulin (WT-hβ2m) in the joints of long-term hemodialysis patients is the hallmark of dialysis-related amyloidosis. In vitro, WT-hβ2m does not form amyloid fibrils at physiological pH and temperature unless co-solvents or other reagents are added. Therefore, understanding how fibril formation is initiated and maintained in the joint space is important for elucidating WT-hβ2m aggregation and dialysis-related amyloidosis onset. Here, we investigated the roles of collagen I and the commonly administered anticoagulant, low-molecular-weight (LMW) heparin, in the initiation and subsequent aggregation phases of WT-hβ2m in physiologically relevant conditions. Using thioflavin T fluorescence to study the kinetics of amyloid formation, we analyzed how these two agents affect specific stages of WT-hβ2m assembly. Our results revealed that LMW-heparin strongly promotes WT-hβ2m fibrillogenesis during all stages of aggregation. However, collagen I affected WT-hβ2m amyloid formation in contrasting ways: decreasing the lag time of fibril formation in the presence of LMW-heparin and slowing the rate at higher concentrations. We found that in self-seeded reactions, interaction of collagen I with WT-hβ2m amyloid fibrils attenuates surface-mediated growth of WT-hβ2m fibrils, demonstrating a key role of secondary nucleation in WT-hβ2m amyloid formation. Interestingly, collagen I fibrils did not suppress surface-mediated assembly of WT-hβ2m monomers when cross-seeded with fibrils formed from the N-terminally truncated variant ΔN6-hβ2m. Together, these results provide detailed insights into how collagen I and LMW-heparin impact different stages in the aggregation of WT-hβ2m into amyloid, which lead to dramatic effects on the time course of assembly.

PRIMARY HIP ARTHROPLASTY IN PATIENTS WITH END-STAGE OF CHRONIC KIDNEY DISEASE (LITERATURE REVIEW)

The authors present a review of current national and international literature related to the specifics of primary hip joint arthroplasty in patients with end-stage of chronic kidney disease. epidemiology aspects of such pathology are covered in detail. Screening of the patients with hip joint pathology undergoing substitute renal therapy remains a significant issue. The authors present the outcomes of use of various implant types and their fixation in primary hip joint arthroplasty such as cemented, cementless and monopolar prostheses, as well as consider features and structure of complications following primary replacements in such patients. unfortunately, the national literature lacks sufficient number of publications on the present problem. In addition, the paper presents a promising area for development of specialized care to patients on hemodialysis with hip joint pathology.

Monitoring Chronic Hemodialysis Patients: A Questionnaire-Based Survey

Background

The monitoring program for patients on regular hemodialysis treatment (RDT) is not well defined yet by current international guidelines (CIG).

Methods

To evaluate the extent to which CIG are implemented, we sent a questionnaire to 100 Italian hemodialysis units (DU) with questions concerning: (a) the frequency with which routine tests were performed for the follow-up of patients on RDT; (b) which other non-routine tests were performed. We analyzed the response data and compared them with the CIG.

Results

We received 37 replies. We found several differences between the monitoring program of our respondents and the CIG.

Conclusion

Because of the small number of responses, this survey is only preliminary; however, it shows the difficulty nephrologists have in using the CIG to create a correct monitoring program in patients on RDT. Although our analysis is limited to 37 DUs, it suggests that specific guidelines are necessary to optimize the management of patients on RDT.

Association Between Environmental Particulate Matter and Carpal Tunnel Syndrome in Patients Undergoing Hemodialysis

BACKGROUND/AIMS

The deposition of β2-microglobulin induced by reactive inflammation causing carpal tunnel syndrome (CTS) is one of the complications of dialysis-related amyloidosis in maintenance hemodialysis (MHD) patients. Air pollution levels, especially particulate matter with an aerodynamic diameter of <2.5 mm (PM2.5), have significantly been associated with the elevation of systemic inflammatory markers. There is no previous research on possible associations between CTS and PM2.5.

METHODS

This study enrolled 866 MHD patients treated at the outpatient HD centers. Senior neurologists diagnosed the presence of CTS. Air pollution levels were recorded by a network of 27 monitoring stations near or in the patients' living areas throughout Taiwan. The 12- and 24-month average concentrations of PM with an aerodynamic diameter of <10 and <2.5 mm (PM10 and PM2.5, respectively), sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone were included.

RESULTS

Multivariate logistic regression analyses showed that HD duration, the normalized protein catabolic rate (nPCR), hypoalbuminemia (albumin < 4 g/dl), and the mean previous 12-month environmental PM2.5 were positively associated with CTS; HD duration, nPCR, hypoalbuminemia (albumin < 4 g/dl), and the mean previous 24-month environmental PM2.5 were positively associated with CTS; HD duration, hypoalbuminemia (albumin < 4 g/dl), and previous 12-month PM2.5 excess days were positively associated with CTS; and HD duration, nPCR, hypoalbuminemia (albumin < 4 g/dl), and previous 24-month PM2.5 excess days were positively associated with CTS.

CONCLUSION

PM2.5 levels and PM2.5 excessing days were positively correlated with CTS.

Doxycycline treatment in dialysis related amyloidosis: discrepancy between antalgic effect and inflammation, studied with FDG-positron emission tomography: a case report

Background

No effective treatment is currently available and dialysis related amyloidosis continues to be invalidating in long-term dialysis patients. A recent case series reported reduction of osteoarticular pain on doxycycline treatment, extending the indications of this drug, used in other uncommon forms of amyloidosis, to dialysis patients. Explanations of the antalgic effect were the anti-inflammatory properties and anti-coiling effects of tetracycline.

Case presentation

Our report regards a 54-year-old woman, who was never transplanted and has been on hemodialysis and hemodiafiltration for overall 37 years, due to renal hypoplasia. In spite of high efficiency hemodiafiltration, she complained of increasing, invalidating osteoarticular pain; history and imaging suggested beta-2 microglobulin amyloid. Positron emission tomography (PET scan) identified metabolically active lesions in the involved settings. Low-dose doxycycline (100 mg/day) was started, leading to a considerable decrease in pain (over 6 months, from 7 to 8 to 4–5 on a 0–10 scale). At 6 months, a PET scan showed unmodified or increased uptake in the involved settings.

Conclusions

In summary, the previously described antalgic effect of doxycycline in dialysis related amyloidosis is confirmed in our case, the first studied using PET scan. The pattern at PET can suggests that the antalgic effect is independent from inflammation and points to other factors, such as interaction with fibril geometry or with bone structure.

The influence of renal dialysis and hip fracture sites on the 10-year mortality of elderly hip fracture patients: A nationwide population-based observational study

Hip fractures in older people requiring dialysis are associated with high mortality. Our study primarily aimed to evaluate the specific burden of dialysis on the mortality rate following hip fracture. The secondary aim was to clarify the effect of the fracture site on mortality. A retrospective cohort study was conducted using Taiwan's National Health Insurance Research Database to analyze nationwide health data regarding dialysis and non-dialysis patients ≥65 years who sustained a first fragility-related hip fracture during the period from 2001 to 2005. Each dialysis hip fracture patient was age- and sex-matched to 5 non-dialysis hip fracture patients to construct the matched cohort. Survival status of patients was followed-up until death or the end of 2011. Survival analyses using multivariate Cox proportional hazards models and the Kaplan-Meier estimator were performed to compare between-group survival and impact of hip fracture sites on mortality. A total of 61,346 hip fracture patients were included nationwide. Among them, 997 dialysis hip fracture patients were identified and matched to 4985 non-dialysis hip fracture patients. Mortality events were 155, 188, 464, and 103 in the dialysis group, and 314, 382, 1505, and 284 in the non-dialysis group, with adjusted hazard ratios (associated 95% confidence intervals) of 2.58 (2.13-3.13), 2.95 (2.48-3.51), 2.84 (2.55-3.15), and 2.39 (1.94-2.93) at 0 to 3 months, 3 months to 1 year, 1 to 6 years, and 6 to 10 years after the fracture, respectively. In the non-dialysis group, survival was consistently better for patients who sustained femoral neck fractures compared to trochanteric fractures (0-10 years' log-rank test, P < .001). In the dialysis group, survival of patients with femoral neck fractures was better than that of patients with trochanteric fractures only within the first 6 years post-fracture (0-6 years' log-rank, P < .001). Dialysis was a significant risk factor of mortality in geriatric hip fracture patients. Survival outcome was better for non-dialysis patients with femoral neck fractures compared to those with trochanteric fractures throughout 10 years. However, the survival advantage of femoral neck fractures was limited to the first 6 years postinjury among dialysis patients.

Multicentre cross-sectional study for bone-articular lesions associated with dialysis related amyloidosis in Japan

AIM

Dialysis-related amyloidosis (DRA) exhibits multiple bone-articular lesions, such as carpal tunnel syndrome (CTS), trigger finger (TF), spinal canal stenosis (SCS), destructive spondyloarthropathy (DSA), bone cysts, and joint pains. DRA leads to a decrease in activities of daily living (ADL). We investigated the initiation of CTS and TF, and evaluated the relationship between walking disturbances and bone-articular lesions or joint pains.

METHODS

A multicentre cross-sectional study was performed. Eighty-two patients with clinical DRA from 20 hospitals in Japan were evaluated.

RESULTS

Of the 82 patients, the first symptom of DRA was CTS in 39 patients (47.6%) and TF in 21 (25.6%). The mean new-onset vintages of 21 earlier cases in the CTS and TF groups were 86.1 ± 36.3 and 133.2 ± 56.4 (mean ± SD) months, respectively (P = 0.0091). The development of SCS and DSA appeared to be later than CTS and TF. Multiple regression analysis revealed that knee joint pain was a significant contributor to walking disturbances.

CONCLUSION

Carpal tunnel syndrome appeared significantly earlier than TF since the initiation of dialysis. In the advanced phase, knee joint pain was a major cause of decreased ADL in patients with clinical DRA.

Dialysis-related amyloidosis: challenges and solutions

Amyloidosis refers to the extracellular tissue deposition of fibrils composed of low-molecular-weight subunits of a variety of proteins. These deposits may result in a wide range of clinical manifestations depending upon their type, location, and the amount of deposition. Dialysis-related amyloidosis is a serious complication of long-term dialysis therapy and is characterized by the deposition of amyloid fibrils, principally composed of β2 microglobulins (β2M), in the osteoarticular structures and viscera. Most of the β2M is eliminated through glomerular filtration and subsequent reabsorption and catabolism by the proximal tubules. As a consequence, the serum levels of β2M are inversely related to the glomerular filtration rate; therefore, in end-stage renal disease patients, β2M levels increase up to 60-fold. Serum levels of β2M are also elevated in several pathological conditions such as chronic inflammation, liver disease, and above all, in renal dysfunction. Retention of amyloidogenic protein has been attributed to several factors including type of dialysis membrane, prolonged uremic state and/or decreased diuresis, advanced glycation end products, elevated levels of cytokines and dialysate. Dialysis treatment per se has been considered to be an inflammatory stimulus, inducing cytokine production (such as interleukin-1, tumor necrosis factor-α, interleukin-6) and complement activation. The released cytokines are thought to stimulate the synthesis and release of β2M by the macrophages and/or augment the expression of human leukocyte antigens (class I), increasing β2M expression. Residual renal function is probably the best determinant of β2M levels. Therefore, it has to be maintained as long as possible. In this article, we will focus our attention on the etiology of dialysis-related amyloidosis, its prevention, therapy, and future solutions.

Painful and painless shoulder magnetic resonance imaging comparisons in hemodialysis patients and correlation with clinical findings

BACKGROUND

Shoulder pain is frequently observed in haemodialysis patients.

OBJECTIVE

To compare haemodialysis patients with or without shoulder pain in terms of shoulder motion ranges, β2 microglobulin levels and magnetic resonance imaging findings.

METHODS

Forty-three patients undergoing dialysis were enrolled, of which 23 patients had explicit shoulder pain at night, which appeared during dialysis. Range of joint motion and impingement tests were evaluated. β 2 microglobulin value was recorded. MRI was used to evaluate rotator cuff tendons for thickness, homogeneity, integrity and presence of effusion.

RESULTS

Ranges of motion were significantly lower in the painful shoulder group. Supraspinatus tendon thickness and the number of areas with effusion were higher in the painful group. There was a positive correlation between the β 2 microglobulin level and supraspinatus (r:0.352 p< 0.05) and subscapular (r:0.454 p< 0.05) tendon thicknesses. While effusion areas and pain (r:0.351 p< 0.05) showed positive correlation, there was a negative correlation between pain and shoulder motion ranges.

CONCLUSIONS

Shoulder pain in dialysis patients can be related with tendon thickness and effusion. While the β 2 microglobulin level affects tendon thickness, it has no relation to pain and movement constraint.

Utility of Ultrasonography of the Median Nerve With a High-Frequency Probe for the Diagnosis of Dialysis-Related Carpal Tunnel Syndrome

This cross-sectional study aimed to determine the utility of ultrasonography with improved resolution using a high-frequency probe for dialysis-related carpal tunnel syndrome (CTS). This study targeted 125 hemodialysis patients at our hospital. A 12 MHz probe was placed on the carpal tunnel area to identify the median nerve. The compression rate of the nerve was calculated by measuring the smallest diameter of the compressed nerve and largest diameter of the unaffected part. To quantify CTS symptoms, we determined the presence of Tinel's sign, measured pinch strength, and used questionnaires to assess numbness and pain. The association of these clinical data with the compression rate was examined. Mean compression rate was 12.1 ± 1.1%. The compression rate cutoff value for those positive with Tinel's sign was 25%, (sensitivity and specificity were 0.80 and 0.91, respectively), and that for those with a history of CTS surgery was 25% (sensitivity and specificity were 0.67 and 0.89, respectively). Multiple regression analysis identified duration of dialysis, β2-microglobulin(β2-Mg) concentration, positivity for Tinel's sign, history of CTS surgery, and pinch strength as independent compression rate determinants. Notably, compression rates were significantly higher in patients with a ≥4-year duration of dialysis and a β2-Mg level of 20 mg/L or more. The compression rate of the median nerve measured by an improved ultrasound device significantly correlated with clinical symptoms, medical history, and serological features associated with dialysis-related CTS. Because ultrasonography is non-invasive, the examination might be a simple method especially for early diagnosis of dialysis-related CTS.

Radiologic case study. Dialysis-related amyloidosis

A 59-year-old woman presented with worsening bilateral hip pain for 6 months. She had been receiving hemodialysis for 12 years.

The optimal timing of hemoperfusion component in combined hemodialysis-hemoperfusion treatment for uremic toxins removal

The combination of hemodialysis-hemoperfusion (HDHP) has been proved to be superior to hemodialysis (HD) in eliminating uremic toxins. There are two methods of combination of HD and HP: the HP regime is utilized during the first two-hour an early HP conducted HDHP (EHDHP) or the last two-hour late HP conducted HDHP (LHDHP) of 4 h regular HD session. The present study was to compare these two methods in uremic toxins removal. Twenty adult chronic HD patients were enrolled in this self-control method study. The patients were randomized to receive one session of EHDHP or LHDHP. Two weeks later, the dialysis modalities were switched. The reduction ratio (RR) of targeted uremic toxins for each session was assessed. Both EHDHP and LHDHP showed a significant removal of small water-soluble solutes, middle-sized toxins and cytokines as well (p < 0.05). There were no significant differences between two methods in RR of small water-soluble solutes, like urea and creatinine. For middle-sized molecules and cytokines, such as PTH, β(2)-M, IL-1, IL-6, and TNF-α, the RR was markedly increased in LHDHP than that in EHDHP (p < 0.05). LHDHP showed no more intradialytic events than EHDHP. The combination of HD and HP in the last two hours in one hemodialysis session had more effect on eliminating middle-sized toxins and cytokines.

Impact of advanced dialysis technology on the prevalence of dialysis-related amyloidosis in long-term maintenance dialysis patients

Dialysis-related amyloidosis (DRA) is a unique type of amyloidosis (beta-2 microglobulin) predominantly in end-stage renal disease. Its clinical manifestations add to increased morbidity and reduced quality of life. There seems to be a relative risk reduction in DRA manifestations when hemodialysis (HD) patients are treated with advanced HD technology, but changes of the course of DRA are uncertain. The aim of our investigation was to evaluate the prevalence and severity of carpal tunnel syndrome (CTS) in long-term dialysis patients receiving either conventional or high-flux, online-produced ultrapure dialysis fluid. The cross-sectional study included 147 HD patients (at least 10 years). The definitive diagnosis of CTS was made histologically or by the coexistence of CTS with other radiological DRA manifestations (bone cysts, arthropathies). The two HD patient groups did not differ significantly in age at start of HD, gender, major co-morbid diseases, anuria, and dialysis vintage. The conventional HD group had significantly higher circulating beta-2 microglobulin and C-reactive protein (CRP) levels. The prevalence of DRA was 68% for the conventional HD group and 28% for the advanced HD group. Duration of dialysis treatment was the only significant risk factor for the development of clinical DRA manifestations in both study groups, but CTS, bone cysts, or arthropathies occurred significantly earlier in conventional HD patients. The prevalence and severity of DRA have decreased with advances in dialysis technology during the last two decades, although its occurrence is simply delayed.

Hemodiafiltration improves plasma 25-hepcidin levels: a prospective, randomized, blinded, cross-over study comparing hemodialysis and hemodiafiltration

Background/Aims

Data from studies comparing the effect of hemodiafiltration (HDF) and conventional hemodialysis (HD) on clinically important outcomes are insufficient to support superiority of HDF. None of these studies has been participant-blinded.

Methods

We performed a prospective, randomized, and patient-blinded cross-over study. Twenty patients on chronic HD received either HD for 2 months followed by post-dilution HDF for 2 months or in opposite order. A range of clinical parameters, as well as markers of inflammation, oxidative stress and iron metabolism was measured.

Results

The two treatments were similar with respect to dialysis-related complications, quality of life, and the biomarkers of oxidative stress and inflammation. Compared to HD, 25-hepcidin and β₂-microglobulin were 38 and 32%, respectively, lower after 60 days of HDF (p < 0.001 and p < 0.01, respectively). The consumption of ESA (erythropoietin-stimulating agent) and LMWH (low-molecular-weight heparin) was significantly higher with HDF.

Conclusion

In short term, HDF is not superior to HD regarding dialysis-related complications. The higher ESA consumption observed with HDF can be explained by blood clotting in tubing and dialyzers, as more anticoagulation was needed with post-dilution HDF. In a longer perspective, lowering serum hepcidin levels may improve pathological iron homeostasis.

Amyloidosis

The term amyloid describes the deposition in the extracellular space of certain proteins in a highly characteristic, insoluble fibrillar form. Amyloidosis describes the various clinical syndromes that occur as a result of damage by amyloid deposits in tissues and organs throughout the body. The clinical significance of amyloid varies enormously, ranging from incidental asymptomatic deposits to localized disease through to rapidly fatal systemic forms that can affect multiple vital organs. Currently available therapy is focused on reducing the supply of the respective amyloid fibril precursor protein and supportive medical care, which together have greatly improved survival. Chemotherapy and anti-inflammatory treatment for the disorders that underlie AL and AA amyloidosis are guided by serial measurements of the respective circulating amyloid precursor proteins, i.e. serial serum free light chains in AL and serum amyloid A protein in AA type. Quality of life and prognosis of some forms of hereditary systemic amyloidosis can be improved by liver and other organ transplants. Various new therapies, ranging from silencing RNA, protein stabilizers to monoclonal antibodies, aimed at inhibiting fibril precursor supply, fibril formation or the persistence of amyloid deposits, are in development; some are already in clinical phase.

Atypical rapid progression of osteoarticular amyloidosis involving the hip in a patient on hemodialysis using polyacrylonitrile membranes

Amyloidosis related to dialysis is a well-known complication affecting many organ systems, in particular the musculoskeletal system. In 1985 Shirahama et al. (Biochem Biophys Res Commun 53:705-709, 1985) identified beta-2 microglobulin (MG) as the offending constituent by using protein purification techniques. Amyloidosis has been increasing in prevalence because of longer life spans and increased chronic medical conditions such as end-stage renal disease. When dialysis-related amyloidosis involves the musculoskeletal system, it affects the shoulder girdle, the so called shoulder pad sign, the wrist, hip, knee, and spine (Resnick, Diagnosis of bone and joint disorders, 4th edn., pp. 2054-2058 and 2176-2183, 2002). Other osteoarticular manifestations of amyloidosis include osteoporosis, lytic lesions, and pathologic fractures. It has been well documented that the prevalence of amyloid is dependent on duration of dialysis-over 90% in patients on dialysis for over 7 years (Jadoul, Nephrol Dial Transplant 13:61-64, 1998). However, a recent changeover to high-flux membranes used in hemofiltration has been reported to delay its onset (Campistol et al., Contrib Nephrol 125:76-85, 1999). We report on the radiographic, nuclear medicine, and computed tomography (CT) findings of osteoarticular amyloidosis involving the hip, and sequence its atypical rapid onset. The imaging, histopathological findings, and differential diagnosis are discussed.

Heparan sulfate proteoglycans in amyloidosis

Amyloidosis is a generic term for a group of diseases characterized by deposits in different organ systems of insoluble materials composed mainly of distinct fibrillar proteins named amyloid. Besides amyloid, heparan sulfate proteoglycan (HSPG), is commonly found in most amyloid deposits, suggesting that HS/HSPG may be functionally involved in the pathogenesis of amyloidosis. HS or HSPG is found to interact with a number of amyloid proteins, displaying a promoting effect on amyloid fibrilization in vitro. In addition, HS is reported to be involved in processing amyloid precursor proteins and mediate amyloid toxicity. Although little is known about the in vivo mechanisms regarding the codeposition of HS with amyloid proteins in different amyloid diseases, experiments carried out in animal models, especially in transgenic mouse model where HS molecular structure is modified, support an active role for HS in amyloidogenesis. Further experimental evidence is required to strengthen these in vivo findings at a molecular level. Animal models that express mutant forms of HS due to knockout of the enzymes involved in glycosaminoglycan (GAG) biosynthesis are expected to provide valuable tools for studying the implications of HS, as well as other GAGs, in amyloid disorders.

Solute kinetics with short-daily home hemodialysis using slow dialysate flow rate

"NxStage System One()" is increasingly used for daily home hemodialysis. The ultrapure dialysate volumes are typically between 15 L and 30 L per dialysis, substantially smaller than the volumes used in conventional dialysis. In this study, the impact of the use of low dialysate volumes on the removal rates of solutes of different molecular weights and volumes of distribution was evaluated. Serum measurements before and after dialysis and total dialysate collection were performed over 30 times in 5 functionally anephric patients undergoing short-daily home hemodialysis (6 d/wk) over the course of 8 to 16 months. Measured solutes included beta(2) microglobulin (beta(2)M), phosphorus, urea nitrogen, and potassium. The average spent dialysate volume (dialysate plus ultrafiltrate) was 25.4+/-4.7 L and the dialysis duration was 175+/-15 min. beta(2) microglobulin clearance of the polyethersulfone dialyzer averaged 53+/-14 mL/min. Total beta(2)M recovered in the dialysate was 106+/-42 mg per treatment (n=38). Predialysis serum beta(2)M levels remained stable over the observation period. Phosphorus removal averaged 694+/-343 mg per treatment with a mean predialysis serum phosphorus of 5.2+/-1.8 mg/dL (n=34). Standard Kt/V averaged 2.5+/-0.3 per week and correlated with the dialysate-based weekly Kt/V. Weekly beta(2)M, phosphorus, and urea nitrogen removal in patients dialyzing 6 d/wk with these relatively low dialysate volumes compared favorably with values published for thrice weekly conventional and with short-daily hemodialysis performed with machines using much higher dialysate flow rates. Results of the present study were achieved, however, with an average of 17.5 hours of dialysis per week.

Localized insulin-derived amyloidosis in patients with diabetes mellitus: a case report

Three patients with insulin dependent type 1 diabetes mellitus and one with insulin dependent type 2 diabetes mellitus developed localized amyloid tumors at their general insulin injection sites. All 4 patients (two women and two men) were treated with modern recombinant human insulin or insulin analogues. In addition, 1 patient had used both recombinant and animal insulin. The amyloid tumors were resected and examined histologically using Congo red staining and immunohistochemistry. Insulin was found to be the major component of the amyloid tumors in all four patients. These 4 cases were diagnosed recently within a relatively short period of time, which leads to the conjecture that local insulin-derived amyloid tumors remain principally a differential diagnosis of skin tumors in insulin-dependent diabetic patients.

Beta2-microglobulin: emerging as a promising cancer therapeutic target

Beta2-microglobulin, a MHC class I subunit, is found to act similarly to a prototypical oncogenic factor capable of stimulating growth and progression of various cancers and plays a key regulatory role in stimulating cancer bone metastasis. Free beta2M in serum or urine has been regarded as an independent biomarker in several cancers. Specific antibodies to beta2M have remarkable tumoricidal activity for both solid tumors and blood malignancies and are shown to be selective to tumor cells, but caused no toxicity in normal cells. These surprising data strongly suggest that beta2M is a promising new therapeutic target for human cancers.

Characteristics of dialysis-related amyloidosis in patients on haemodialysis therapy for more than 30 years

BACKGROUND

Dialysis-related amyloidosis is one of the chronic the complications of haemodialysis. We conducted an investigation of dialysis-associated amyloidosis in extremely long-term survivors.

METHODS

Twenty-one patients on haemodialysis for more than 30 years ('30+' group) and 13 patients on haemodialysis for 20-30 years ('20-30' group) at Sangenjaya Hospital were enrolled in this study. The frequencies of operations for conditions related to haemodialysis-related amyloidosis were examined.

RESULTS

The mean age at the start of haemodialysis was younger in the '30+' group (29.1 +/- 7.3 years) than in the '20-30' group (40.5 +/- 8.2 years, P = 0.0003). Eighteen (85.7%) patients had undergone surgery for CTS, six (28.6%) had undergone surgery for trigger finger and six (28.6%) had undergone surgery for cervical destructive spondyloarthropathy (DSA) at 30 years after the start of haemodialysis therapy. Patients who were over the age of 30 years at the start of dialysis therapy more frequently underwent CTS operations (100%) than those who were under 30 years of age at the start of dialysis (76.9%; P = 0.025) in the '30+' group at 30 years after the start of haemodialysis. The frequencies of operations for CTS did not differ significantly between the '20-30' group and the '30+' group.

CONCLUSIONS

Haemodialysis-associated amyloidosis was common in extremely long-term survivors. Even though the mean age at the start of haemodialysis was younger in the '30+' group than in the '20-30' group, the frequency of operations for CTS did not differ. This may be attributable to the recent advances in haemodialysis technologies.

Beta2-microglobulin amyloidosis in hemodialysis and peritoneal dialysis patients

Beta(2)-microglobulin (beta(2)-M) amyloidosis is an important cause of morbidity in patients on dialysis. In this cross-sectional study, we evaluated supraspinatus tendon thickness (as a measure of shoulder involvement from beta(2)-M amyloidosis) in patients who are on hemodialysis (HD) compared with those on continuous ambulatory peritoneal dialysis (CAPD). In 27 patients on HD who were treated with high-flux dialyzers, 31 patients on CAPD, and 31 healthy volunteers, we performed bilateral shoulder magnetic resonance imaging and measured the supraspinatus tendon thickness using electronic calipers. There were no statistically significant differences in age or dialysis duration between the HD and CAPD patients. Each patient was asked about the presence or absence of shoulder pain. The supraspinatus tendon thickness in HD patients (mean thickness 6.6 +/- 1.3 mm, range 3.20-8.80 mm, N = 53) and CAPD patients (6.8 +/- 0.9 mm, range 4.9-8.8 mm, N = 61) was not significantly different (P = 0.289); however, the mean thickness in either group was higher than in the healthy controls (5.5 +/- 0.6 mm, range 4.3-6.8 mm, N = 61) (HD patients vs. controls: P = 0.000; CAPD patients vs. controls: P = 0.000). Patients with shoulder pain had higher mean supraspinatus tendon thickness measurements than patients without shoulder pain (P = 0.042). The thickness of supraspinatus tendons is not significantly different between patients on CAPD and HD. An association exists between shoulder pain and mean supraspinatus tendon thickness. This hidden complication of ESRD should be further studied in larger populations of dialysis patients.

Review Article: is it time to embrace haemodiafiltration for centre-based haemodialysis?

Improvements in survival in dialysis patients over the past few decades have been disappointing. Recent prospective trials such the haemodialysis study have not shown conclusive improvements. Two recent observational studies have found a striking survival advantage for haemodiafiltration (HDF). This review covers the differences between HDF and conventional haemodialysis (HD) and the history of the technological advances in the HDF technique. In addition, it explores the putative benefits of HDF over HD. While the observational studies provide a basis for optimism that HDF will provide benefit to dialysis patients, definitive conclusions cannot be drawn until the results of randomized controlled trials are available. While the evidence in favour of HDF at this stage is observational only, there are no studies suggesting that the treatment is detrimental. The use of HDF should probably be increased, particularly in centres where an increase in the frequency and duration of dialysis cannot be readily achieved.

Strong correlation of B2-microglobulin (B2-m) with procalcitonin (PCT) in the serum of chronic hemodialysis patients: a role for infections in the dialysis-related amyloidosis?

INTRODUCTION

Infections trigger the activation of defensive cells capable to produce and release B(2)-microglobulin (B(2)-m). Procalcitonin (PCT), secreted by a wide range of human cells, included the aforementioned defensive cells, is generally considered a sensitive and specific marker of infection. In this prospective study, we examined the possibility that infections, as detected by increased levels of PCT, increase the serum levels of B(2)-m in chronic hemodialysis (CHD) patients, possibly affecting the rate of progression of dialysis-related amyloidosis (DRA).

METHODS

For a period of four months, 76 CHD patients, 45 men/31 women, mean age 63 +/- 15.7 years, with no residual renal function and in HD for 46 +/- 50 months were studied bimonthly. Blood was drawn, at baseline T(0), two months T(2), and four months T(4), for measuring hematocrit (Ht), white blood cells (WBC), erythrocyte sedimentation rate (ESR), blood urea and serum creatinine, protein (albumin, globulin), C-reactive protein (CRP), and PCT kappa alpha iota B(2)-m. Any events (especially infections) in the preceding 10-day period were recorded.

RESULTS

At baseline, 100% of all B(2)-m measurements were abnormal (>2.4 mg/L), 13.4% of PCT values were increased (>1.5 ng/mL), and 49.4% of CRP values exceeded the lower limit of 5 mg/L with no statistically significant differences between the results of the three periods of the study. Statistically significant, in all periods, was the linear positive correlation of B(2)-m with PCT (T[0]: p < 0.001, T[2]: p < 0.004, T[4]: p < 0.001). Also, statistically significant (p < 0.005) was the positive correlation of B(2)-m to HD vintage.

CONCLUSIONS

In this study, the strong positive correlation of B(2)-m to PCT probably signifies that the (mainly subclinical) infections increase B(2)-m production in CHD patients intensifying the problem of HD-related amyloidosis.

Adynamic bone in patients with chronic kidney disease

Adynamic bone in patients with chronic kidney disease (CKD) is a clinical concern because of its potential increased risk for fracture and cardiovascular disease (CVD). Prevalence rates for adynamic bone are reportedly increased, although the variance for its prevalence and incidence is large. Differences in its prevalence are largely attributed to classification and population differences, the latter of which constitutes divergent groups of elderly patients having diabetes and other comorbidities that are prone to low bone formation. Most patients have vitamin D deficiency and the active form, 1,25-dihydroxyvitamin D, invariably decreases to very low levels during CKD progression. Fortunately, therapy with vitamin D receptor activators (VDRAs) appears to be useful in preventing bone loss, in part, by its effect to stimulate bone formation and in decreasing CVD morbidity, and should be considered as essential therapy regardless of bone turnover status. Future studies will depend on assessing cardiovascular outcomes to determine whether the risk/reward profile for complications related to VDRA and CKD is tolerable.

[What's new in hemodialysis]

Dialysis is a complement to or a substitute for renal transplantation. Mortality of dialysis patients remains too high - 9-22%/year - and is associated above all with old age and comorbidities but also with the quantity and quality of hemodialysis. Hemodialysis must be more personalized, with a possible increase in its frequency (daily) or in the duration of sessions (longer than 4.5 h). Chronic inflammation, present in 30% of patients, is a source of morbidity and mortality. It must be detected by ultrasensitive CRP (C-reactive protein) assays and its cause sought and treated. Metabolism of phosphate and calcium is too often inadequately controlled, despite the contribution of new very active molecules. The resultant vascular calcifications are an important cardiovascular risk factor. Progress in dialysis techniques also plays a role in improving quality of life and life span: use of highly permeable membranes, ultrapure dialysate, closed-loop biofeedback volume control, and maintenance of thermal balance.

New insights into systemic amyloidosis: the importance of diagnosis of specific type

PURPOSE OF REVIEW

This review aims to summarize recent developments in the area of systemic amyloidoses with emphasis on pathologic diagnosis.

RECENT FINDINGS

In recent years, management of amyloidosis has shifted from a purely supportive approach to quite diverse, radical and aggressive treatments. The central issue is the understanding that treatment of systemic amyloidoses depends on the molecular type of the amyloid protein. In the United States and the Western world, AL-amyloidosis is the most prevalent type of systemic amyloidosis, but hereditary amyloidoses are being diagnosed with increasing frequency; genetics also plays a role in a subset of familial AA amyloidoses. The biggest challenge is in the diagnosis of AL-type with confidence and in differentiation of AL and hereditary amyloidoses. While careful clinico-pathologic correlation is recommended for all patients with amyloidosis, it is, in itself, not a substitute for amyloid typing.

SUMMARY

The diagnosis of the amyloid type ultimately depends on the examination of the amyloid protein within the deposits. The role of immunohistochemistry - the current standard of care in amyloid typing - is evolving with emergence of alternative biochemical methods. Amyloid, being essentially a protein disorder, presents an attractive venue for the application of proteomics methodologies, despite their inherent complexities.