The use of medium cut-off (MCO) polyarylethersulfone and polyvinylpyrrolidone blend membrane is an emerging mode in hemodialysis. Recent studies have shown that MCO membranes exhibit a middle high molecular weight uremic toxin clearance superior to standard high flux hemodialysis. We conducted a systematic literature review and meta-analysis of randomized controlled trials to investigate whether MCO membranes efficiently increase the reduction ratio of middle molecules, and to explore the potential clinical applications of MCO membranes. We selected articles that compared beta 2-microglobulin (β2M), kappa free light chain (κFLC), lambda free light chain (λFLC), interleukin-6 (IL-6), and albumin levels among patients undergoing hemodialysis. Five randomized studies with 328 patients were included. The meta-analysis demonstrated a significantly higher reduction ratio of serum β2M (p < 0.0001), κFLC (p < 0.0001), and λFLC (p = 0.02) in the MCO group. No significant difference was found in serum IL-6 levels after hemodialysis. Albumin loss was observed in the MCO group (p = 0.04). In conclusion, this meta-analysis study demonstrated the MCO membranes’ superior ability to clear β2M, κFLC, and λFLC. Serum albumin loss is an issue and should be monitored. Further studies are expected to identify whether MCO membranes could significantly improve clinical outcomes and overall survival.

For decades, beta 2 microglobulin (B2M) has been a subject of great interest in nephrology and other fields such as multiple myeloma. B2M, a 99 amino acid protein, is associated with amyloid deposits in patients undergoing renal replacement therapy (RRT). The source of information is published articles on B2M in chronic renal failure since 1960. We have reviewed literature published since 1960 to date, highlighting the milestones of the role of B2M in chronic kidney disease (CKD) and B2M serum values in patients treated by various RRTs. B2M deposits associated with the disease include carpal tunnel syndrome, spondyloarthropathy, and arthritis of large joints such as the shoulders. The role of RRT in the removal of B2M in CKD is discussed. Recent reports include factors affecting the process of fibrillation and deposition of B2M in tissues. A comparative report of various modalities of treatment on the serum levels of B2M is provided. The presence of significant residual urine output in continuous ambulatory peritoneal dialysis patients may explain why peritoneal dialysis is a modality that is associated with the lowest level of serum B2M. Patients treated with hemodiafiltration or hemodialysis (HD) using high flux dialyzers have lower levels of B2M than those treated by HD with low flux dialyzers. Finally, based on the literature review, an algorithm for RRT using B2M level monitoring and other variables is proposed and needs evaluation in a controlled trial.

OBJECTIVE: Amyloidosis is a systemic or localized disease of protein deposition characterized by amorphous eosinophilic morphology and positivity of Congo Red staining. The typing of amyloidosis is becoming increasingly important because therapeutic agents for each amyloidosis type have been developed. Herein, the authors review the autopsy cases at an institution to reveal the putative Japanese characteristics of each amyloidosis type and evaluate the clinicopathological significance of each type.
METHODS: A total of 131 autopsy cases of systemic and localized amyloidosis were retrieved for classification by immunohistochemistry. Immunohistochemistry for transthyretin, amyloid A (AA), immunoglobulin light-chain kappa and lambda, and β2-microglobulin was performed for all cases.
RESULTS: The 131 amyloidosis cases were classified as follows: 71 cases (54.2%) of transthyretin amyloidosis, 32 cases (24.4%) of AA amyloidosis, 8 cases (6.1%) of light-chain amyloidosis, and 5 cases (3.8%) of β2-microglobulin amyloidosis, along with 15 equivocal cases (11.5%). All cases showed myocardial involvement of amyloidosis. Histopathologically, the transthyretin type was significantly associated with the interstitial and nodular patterns, and with the absence of the perivascular and endocardial patterns. The AA type was significantly associated with the perivascular and endocardial patterns, and with the absence of the nodular pattern.
CONCLUSIONS: The authors revealed the putative characteristics of cardiac amyloidosis in Japan by using autopsy cases. About 90% of amyloidosis cases were successfully classified using only commercially available antibodies.

Amyloid arthropathy is a joint disease associated with systemic amyloidosis. Herein, we present a model case and review the clinicopathologic features and pathophysiology of this disorder. Amyloid arthropathy results from elevation of serum amyloidogenic proteins and their deposition as aggregates in synovial fluid and articular tissues. The most common proteins are beta-2-microglobulin in the context of long-term hemodialysis therapy and immunoglobulin light chains associated with plasma cell proliferations. We provide a comprehensive update on the pathogenesis, clinical manifestations, and pathologic features of amyloid arthropathy. We provide detailed insights on amyloid protein deposition and aggregation in joints and proper details for diagnosis.

Beta-2-microglobulin (B2M) has been suggested as an emerging biomarker for cardiovascular diseases (CVD), including coronary heart disease (CHD) and stroke, and mortality.
Three databases were searched from inception to January 2, 2020, supplemented by scanning reference lists of identified studies. We identified studies that reported associations of baseline serum or plasma B2M and CVD incidence, CVD mortality, or CHD and stroke separately, in either general populations or patients with renal disease. Relative risks (RR) were extracted and harmonized to a comparison of the highest versus lowest third of the distribution of B2M, and the results were aggregated.
Sixteen studies (5 in general populations, and 11 in renal disease populations) were included, involving 30,988 participants and 5391 CVD events. Based on random-effects meta-analysis, the pooled adjusted RRs comparing the highest versus lowest third of the distribution of B2M were 1.71 (95%CI: 1.37-2.13) for CVD, 2.29 (1.51-3.49) for CVD mortality, 1.64 (1.14-2.34) for CHD, and 1.51 (1.28-1.78) for stroke, with little to high heterogeneity between studies (0.0% ≤ I2 ≤ 80.0%). The positive associations between B2M and risks of CVD outcomes remained broadly significant across subgroup analyses. Moreover, the pooled adjusted RRs were 2.51 (1.94-3.26; I2 = 83.7%) for all-cause mortality and 2.64 (1.34-5.23; I2 = 83.1%) for infectious mortality.
Available observational data show that there are moderate positive associations between B2M levels and CVD events and mortality, although few studies have been conducted in general populations.

The prevalence of chronic kidney disease (CKD) is increasing worldwide, and the mortality rate continues to be unacceptably high. The biomarkers currently used in clinical practice are considered relevant when there is already significant renal impairment compromising the early use of potentially successful therapeutic interventions. More sensitive and specific biomarkers to detect CKD earlier on and improve patients\' prognoses are an important unmet medical need. The aim of this review is to summarize the recent literature on new promising early CKD biomarkers of renal function, tubular lesions, endothelial dysfunction and inflammation, and on the auspicious findings from metabolomic studies in this field. Most of the studied biomarkers require further validation in large studies and in a broad range of populations in order to be implemented into routine CKD management. A panel of biomarkers, including earlier biomarkers of renal damage, seems to be a reasonable approach to be applied in clinical practice to allow earlier diagnosis and better disease characterization based on the underlying etiologic process.

Diagnosing central nervous system (CNS) lymphoma remains a challenge. Most patients have to undergo brain biopsy to obtain tissue for diagnosis, with associated risks of serious complications. Diagnostic markers in blood or cerebrospinal fluid (CSF) could facilitate early diagnosis with low complication rates. We performed a systematic literature search for studies on markers in blood or cerebrospinal fluid for the diagnosis CNS lymphoma and assessed the methodological quality of studies with the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2). We evaluated diagnostic value of the markers at a given threshold, as well as differences between mean or median levels in patients versus control groups. Twenty-five studies were included, reporting diagnostic value for 18 markers in CSF (microRNAs -21, -19b, and -92a, RNU2-1f, CXCL13, interleukins -6, -8, and -10, soluble interleukin-2-receptor, soluble CD19, soluble CD27, tumour necrosis factor-alfa, beta-2-microglobulin, antithrombin III, soluble transmembrane activator and calcium modulator and cyclophilin ligand interactor, soluble B cell maturation antigen, neopterin and osteopontin) and three markers in blood (microRNA-21 soluble CD27, and beta-2-microglobulin). All studies were at considerable risk of bias and there were concerns regarding the applicability of 15 studies. CXCL-13, beta-2-microglobulin and neopterin have the highest potential in diagnosing CNS lymphoma, but further study is still needed before they can be used in clinical practice.

Amyloidosis is a poorly understood condition that can wreak havoc on numerous systems within the human body. In addition, this disease can present in multiple forms which each have their own unique physiology and subsequent effects. However, while the literature on the etiology and effect of amyloidosis on various organ systems is numerous, few have highlighted the musculoskeletal manifestations of this devastating disease. This review focuses on the recent research on amyloid deposition in the musculoskeletal system. Additionally, risk factors, classification, differential diagnoses, indications for biopsy, and manifestations of amyloidosis in the musculoskeletal system as well as in other tissues are discussed. Furthermore, the surgical and nonsurgical approaches to treatment are covered. (Journal of Surgical Orthopaedic Advances 27(1):1-5, 2018).

Although glomerular filtration rate (GFR) in children can be measured using a gold-standard technique following injection of an exogenous marker, this invasive and cumbersome technique is not widely available and GFR is commonly estimated using serum levels of endogenous markers. Creatinine, urea, cystatin C, beta-trace protein, and beta-2 microglobulin are well-established endogenous markers of kidney function. These markers differ in site of production and effects of diet and medication, as well as renal-tubular handling and extra-renal elimination. For each marker, different methods are available for measurement. Importantly, the measurements of creatinine and cystatin C have recently been standardized with the introduction of international reference standards. In order to allow estimation of GFR from serum marker concentrations, different equations for estimated GFR (eGFR) have been developed in children, using simple or more complex regression strategies with gold standard GFR measurements as a dependent variable. As a rule, estimation strategies relying on more than one marker - either by calculating the average of single parameter equations or by using more complex equations incorporating several parameters - outperform eGFR estimations using only a single marker. This in-depth review will discuss the physiology, measurement and clinical use of creatinine, urea, cystatin C, beta-trace protein, and beta-2 microglobulin in children. It will also address the generation of eGFR equations in children and provide an overview of currently available eGFR equations for the pediatric age group.

BACKGROUND: Beta-2 Microglobulin (β2M) is a prototypical \"middle molecule\" uremic toxin that has been associated with a higher risk of death in hemodialysis patients. A quantitative description of the relative importance of factors determining β2M concentrations among patients with impaired kidney function is currently lacking.
METHODS: Herein we undertook a systematic review of existing studies reporting patient level data concerning generation, elimination and distribution of β2M in order to develop a population model of β2M kinetics. We used this model and previously determined relationships between predialysis β2M concentration and survival, to simulate the population distribution of predialysis β2M and the associated relative risk (RR) of death in patients receiving conventional thrice-weekly hemodialysis with low flux (LF) and high flux (HF) dialyzers, short (SD) and long daily (LD) HF hemodialysis sessions and on-line hemodiafiltration at different levels of residual renal function (RRF).
RESULTS: We identified 9 studies of 106 individuals and 156 evaluations of or more compartmental kinetic parameters of β2M. These studies used a variety of experimental methods to determine β2M kinetics ranging from isotopic dilution to profiling of intra/inter dialytic concentration changes. Most of the patients (74/106) were on dialysis with minimal RRF, thus facilitating the estimation of non-renal elimination kinetics of β2M. In large scale (N = 10,000) simulations of individuals drawn from the population of β2M kinetic parameters, we found that, higher dialytic removal materially affects β2M exposures only when RRF (renal clearance of β2M) was below 2 ml/min. In patients initiating conventional HF hemodialysis, total loss of RRF was predicted to be associated with a RR of death of more than 20%. Hemodiafiltration and daily dialysis may decrease the high risk of death of anuric patients by 10% relative to conventional, thrice weekly HF dialysis. Only daily long sessions of hemodialysis consistently reduced mortality risk between 7-19% across the range of β2M generation rate.
CONCLUSIONS: Preservation of RRF should be considered one of the therapeutic goals of hemodialysis practice. Randomized controlled trials of novel dialysis modalities may require large sample sizes to detect an effect on clinical outcomes even if they enroll anuric patients. The developed population model for β2M may allow personalization of hemodialysis prescription and/or facilitate the design of such studies by identifying patients with higher β2M generation rate.