Aberrant proximal tubule DNA methylation underlies phenotypic changes related to kidney dysfunction in patients with diabetes.

Epigenetic mechanisms are considered to contribute to diabetic nephropathy by maintaining memory of poor glycemic control during the early stages of diabetes. However, DNA methylation changes in the human kidney are poorly characterized, because of the lack of cell type-specific analysis. We examined DNA methylation in proximal tubules purified from diabetic nephropathy patients and identified differentially methylated CpG sites, given the critical role of proximal tubules in the kidney injury. Hypermethylation was observed at CpG sites annotated to genes responsible for proximal tubule functions, including gluconeogenesis, nicotinamide adenine dinucleotide synthesis, transporters of glucose, water, phosphate, and drugs, in diabetic kidneys, while genes involved in oxidative stress and the cytoskeleton exhibited demethylation. Methylation levels of CpG sites annotated to ACTN1, BCAR1, MYH9, UBE4B, AFMID, TRAF2, TXNIP, FOXO3, and HNF4A were correlated with the estimated glomerular filtration rate, while methylation of the CpG site in RUNX1 was associated with interstitial fibrosis and tubular atrophy. Hypermethylation of G6PC and HNF4A was accompanied by decreased expression in diabetic kidneys. Proximal tubule-specific hypomethylation of metabolic genes related to HNF4A observed in control kidneys was compromised in diabetic kidneys, suggesting a role for aberrant DNA methylation in the dedifferentiation process. Multiple genes with aberrant DNA methylation in diabetes overlapped genes with altered expressions in maladaptive proximal tubule cells, including transcription factors PPARA and RREB1. In conclusion, DNA methylation derangement in the proximal tubules of patients with diabetes may drive phenotypic changes, characterized by inflammatory and fibrotic features, along with impaired function in metabolism and transport.

Efficacy and safety of first-line biological DMARDs in rheumatoid arthritis patients with chronic kidney disease.

OBJECTIVE: To evaluate the efficacy and safety of first-line biological disease-modifying antirheumatic drugs (bDMARDs) in patients with rheumatoid arthritis (RA) with chronic kidney disease (CKD), including those undergoing haemodialysis (HD). METHODS: This retrospective cohort study included 425 patients with RA prescribed their first bDMARDs at two hospitals from 2004 to 2021. Patients were categorised by kidney function and bDMARD modality (TNFα inhibitors (TNFαis), interleukin-6 inhibitors (IL-6is), cytotoxic T-lymphocyte antigen-4 immunoglobulin (CTLA4-Ig)). The primary outcome was the 36-month drug retention rate, with secondary outcomes including changes in Disease Activity Score 28 (DAS28)-C reactive protein (CRP)/erythrocyte sedimentation rate (ESR), prednisolone dosage and reasons for discontinuation. RESULTS: The 36-month drug retention rates by estimated glomerular filtration rate (eGFR) (≥60, 30-60, <30 mL/min/1.73 m2) were as follows: all bDMARDs (45.2%, 32.0%, 41.4%), TNFαis (45.3%, 28.2%, 34.0%), IL-6is (47.4%, 66.7%, 71.4%) and CTLA-4Ig (50.0%, 31.3%, 33.3%). Even in groups with lower kidney function, the drug retention rate of bDMARDs was generally maintained. However, the retention rate of TNFαis was significantly lower in patients with eGFR <30 mL/min/1.73 m2. IL-6is showed the highest retention rate and the lowest discontinuation rate due to ineffectiveness in this group (HR 0.11, 95% CI 0.02 to 0.85, p=0.03). All bDMARDs improved DAS28-CRP/ESR and reduced prednisolone dosage across all groups. CONCLUSION: bDMARDs demonstrated effective and safe profiles in patients with RA with CKD, even among patients on HD. In particular, IL-6is had a significantly higher drug retention rate in patients with an eGFR of <30 mL/min/1.73 m2 and fewer discontinuations due to ineffectiveness. IL-6is were more efficacious as monotherapy compared with the other bDMARDs.

A Case of Autosomal Dominant Polycystic Kidney Disease With Resolution of Massive Pericardial Effusion After Renal Transcatheter Artery Embolization.

A 68-year-old woman being treated with hemodialysis for autosomal dominant polycystic kidney disease was admitted for progressive dyspnea over 6 months. On chest radiography, her cardiothoracic ratio had increased from 52.2% 6 months prior, to 71%, and echocardiography revealed diffuse pericardial effusion and right ventricular diastolic insufficiency. A resultant pericardial tamponade was thought to be the cause of the patient's dyspnea, and therefore a pericardiocentesis was performed, with a total of 2,000mL of fluid removed. However, 21 days later the same amount of pericardial fluid had reaccumulated. The second pericardiocentesis was performed, followed by transcatheter renal artery embolization (TAE). The kidneys, which were hard on palpation before TAE, softened immediately after TAE. After resolution of the pericardial effusion was confirmed, the patient was discharged after 24 days in hospital. Twelve months later, the patient was asymptomatic, the cardiothoracic ratio decreased to 48% on chest radiography and computed tomography revealed no reaccumulation of pericardial effusion. This case illustrates a potential relationship between enlarged kidneys in autosomal dominant polycystic kidney disease and pericardial effusion.

Gastric Burkitt's monomorphic post-transplant lymphoproliferative disorder after kidney transplantation: A case report.

We report on a 53-year-old Japanese man diagnosed with gastric Burkitt's monomorphic post-transplant lymphoproliferative disorder (B-PTLD) after endoscopy for gastric discomfort 28 months after the patient underwent renal transplantation in Ethiopia. Serum Epstein-Barr virus (EBV) tests were negative before transplantation, but the tumor cells collected from a gastric biopsy showed positive EBV-encoded small RNAs (EBER) at B-PTLD onset. Intensive treatment started with R(rituximab)-CHOP therapy and continued with DA-EPOCH-R therapy has been effective, and relapse has not yet occurred. Burkitt lymphoma has a poor prognosis, but B-PTLD may be effectively treated with high-dose chemotherapy. This is a rare case of gastric B-PTLD in a Japanese patient.

Diagnostic value of 18F-fluorodeoxyglucose positron emission tomography and computed tomography for differentiating polymyalgia rheumatica and rheumatoid arthritis: Using classification and regression tree analysis.

OBJECTIVES: Determining which sites were important to differentiate polymyalgia rheumatica (PMR) from rheumatoid arthritis (RA) using 18F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET-CT) is challenging. METHODS: Patients with PMR or RA who were undergoing PET-CT were recruited at two mutual-aid hospitals in Japan between 2009 and 2018. Classification and regression tree (CART) analyses were performed to identify FDG uptake patterns that differentiated PMR from RA. RESULTS: We enrolled 35 patients with PMR and 46 patients with RA. Univariate CART analysis showed that FDG uptake in the shoulder joints, spinous processes of the lumbar vertebrae, pubic symphysis, sternoclavicular joints, ischial tuberosities, greater trochanters, and hip joints differentiated PMR from RA. Multivariate CART analysis revealed that FDG uptake by at least one of the ischial tuberosities had the highest diagnostic value for distinguishing PMR from RA (sensitivity, 77.1%; specificity, 82.6%). We performed the same CART analysis to patients who had not undergone treatment (PMR, n = 28; RA, n = 9). Similar results were obtained, and sensitivity and specificity were increased (sensitivity, 89.3%; specificity, 88.8%). CONCLUSIONS: In PET-CT, FDG uptake by at least one of the ischial tuberosities best discriminates between PMR and RA.

Recent advances in IgG4-related kidney disease.

Recent advances in the management and understanding of immunoglobulin (Ig)G4-related kidney disease (RKD) have emphasized the importance of urgent treatment in IgG4-related tubulointerstitial nephritis. On the other hand, to avoid long-term glucocorticoid toxicity, strategies for early withdrawal of steroids or combination of immunosuppressants, such as rituximab, and the minimum dose of steroids have been pursued. However, disease recurrence after reducing or stopping steroid therapy hampers early withdrawal of glucocorticoid maintenance therapy. In addition, knowledge has accumulated in diagnostic approaches including differential diagnosis of anti-neutrophil cytoplasmic antibodies-associated vasculitis, idiopathic multicentric Castleman's disease, and Rosai-Dorfman disease with kidney lesion, which leads to earlier and precise diagnosis of IgG4-RKD. This review summarizes recent progress in the differential diagnosis of IgG4-RKD and related treatment strategies and recent topics of hypocomplementaemia, membranous glomerulonephritis, and IgG4-related pyelitis and periureteral lesion.

Serum hemoglobin concentration and risk of renal function decline in early stages of diabetic kidney disease: a nationwide, biopsy-based cohort study.

BACKGROUND: Prognosticating disease progression in patients with diabetic kidney disease (DKD) is challenging, especially in the early stages of kidney disease. Anemia can occur in the early stages of kidney disease in diabetes. We therefore postulated that serum hemoglobin (Hb) concentration, as a reflection of incipient renal tubulointerstitial impairment, can be used as a marker to predict DKD progression. METHODS: Drawing on nationally representative data of patients with biopsy-proven DKD, 246 patients who had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 at renal biopsy were identified: age 56 (45-63) years; 62.6% men; Hb 13.3 (12.0-14.5) g/dL; eGFR 76.2 (66.6-88.6) mL/min/1.73 m2; urine albumin-to-creatinine ratio 534 (100-1480) mg/g Crea. Serum Hb concentration was divided into quartiles: ≤12, 12.1-13.3, 13.4-14.5 and ≥14.6 g/dL. The association between serum Hb concentration and the severity of renal pathological lesions was explored. A multivariable Cox regression model was used to estimate the risk of DKD progression (new onset of end-stage kidney disease, 50% reduction of eGFR or doubling of serum creatinine). The incremental prognostic value of DKD progression by adding serum Hb concentration to the known risk factors of DKD was assessed. RESULTS: Serum Hb levels negatively correlated with all renal pathological features, especially with the severity of interstitial fibrosis (ρ = -0.52; P < 0.001). During a median follow-up of 4.1 years, 95 developed DKD progression. Adjusting for known risk factors of DKD progression, the hazard ratio in the first, second and third quartile (the fourth quartile was reference) were 2.74 [95% confidence interval (CI) 1.26-5.97], 2.33 (95% CI 1.07-5.75) and 1.46 (95% CI 0.71-3.64), respectively. Addition of the serum Hb concentration to the known risk factors of DKD progression improved the prognostic value of DKD progression (the global Chi-statistics increased from 55.1 to 60.8; P < 0.001). CONCLUSIONS: Serum Hb concentration, which reflects incipient renal fibrosis, can be useful for predicting DKD progression in the early stages of kidney disease.

Dialysis-related carpal tunnel syndrome in the past 40 years.

PURPOSE AND METHOD: Patients on hemodialysis develop carpal tunnel syndrome (CTS) due to an accumulation of dialysis-related ß2 microglobulin (ß2m) amyloid (DRA). In Japan, dialysis technology has progressed remarkably in the past 40 years and has increased the time until patients require surgery for CTS. However, unclear is whether the time from the start of hemodialysis to the first surgery for CTS is associated with ß2m clearance by the different hemodialysis techniques. Therefore, we retrospectively evaluated ß2m clearance, serum ß2m levels, and the change in the length of this period in patients across 4 periods according to the year that first surgery for CTS was performed: period 1, 1982-1989; period 2, 1990-1999; period 3, 2000-2009; and period 4, 2010-2019. RESULT: A total of 222 patients who met the selection criteria were included. Mean ß2m clearance was -1.8 ± 16.7% in period 1, and improved to 65.4 ± 8.6% in period 3. Accordingly, the serum ß2m value after hemodialysis decreased significantly. The time from the start of hemodialysis to the first surgery for CTS was 12.4 ± 2.9 years in period 1 but increased to 21.8 ± 6.3 years in period 3. In multivariable linear regression analysis, the significant factors contributing to ß2m clearance were periods 2, 3, and 4. In particular, the relation between removal of ß2m and the extension of the dialysis vintage in period 1 and 2 was remarkable compared with periods 3 and 4. CONCLUSION: Our findings indicate that improvement of ß2m clearance via advances in dialysis technology might result in a significant extension in the time between starting HD and the first surgery for CTS.

Clinicopathological discordance in biopsy-proven nephrosclerosis: a nationwide cross-sectional study of the Japan Renal Biopsy Registry (J-RBR).

BACKGROUND: Patients with nephrosclerosis display heterogenous clinical phenotypes, often leading to a clinical diagnosis discordant with pathological nephrosclerosis diagnosis. However, little is known about clinical factors associated with clinicopathological discordance of biopsy-proven nephrosclerosis. METHODS: In a cross-sectional study of 891 patients with biopsy-proven nephrosclerosis registered in the Japan Renal Biopsy Registry (J-RBR) between July 2007 and June 2016, we examined clinical characteristics associated with a pre-biopsy clinical diagnosis discordant with pathological nephrosclerosis diagnosis using multivariable logistic regression with adjustment for relevant clinical characteristics. RESULTS: Overall, the mean (SD) age was 58.6 (13.7) years; 67.6% of patients were male; and 63.2% were on antihypertensive drugs. The median estimated glomerular filtration rate (eGFR) was 43.8 mL/min/1.73 m2 and the median proteinuria was 0.5 g/day. Of the 891 patients, 497 (55.8%) had a clinical diagnosis discordant with pathological nephrosclerosis diagnosis, with chronic nephritic syndrome being the most common (> 75%) discordant clinical diagnosis. After multivariable adjustment, age (odds ratio 1.34, [95% confidence interval, 1.16-1.55], per 10 years increase), eGFR (1.10 [1.00-1.21], per 10 mL/min/1.73 m2 increase), and proteinuria (1.20 [1.03-2.16], per 1 g/day decrease) were found to be significantly associated with the clinicopathological discordance. CONCLUSIONS: Patients with older age, higher eGFR, and lower proteinuria had significantly higher likelihood of being clinically diagnosed with other glomerular disease in patients with biopsy-proven nephrosclerosis. Our findings highlight the heterogeneous clinical phenotypes of nephrosclerosis and suggest the need for continuous improvement of clinical diagnostic accuracy as well as for wider kidney biopsy indications for nephrosclerosis.

Use of biologic agents and methotrexate improves renal manifestation and outcome in patients with rheumatoid arthritis: a retrospective analysis.

BACKGROUND AND PURPOSE: We examined whether advances in treatment strategies from older disease-modifying antirheumatic drugs (DMARDs) to new biologic agents and methotrexate improved renal complications and outcome in patients with rheumatoid arthritis (RA). METHODS: We reviewed records of 156 patients with RA who underwent kidney biopsy at our institute between January 1990 and December 2019. All patients were assigned to one of three periods: period 1, 1990-1999 (n = 48); period 2, 2000-2009(n = 57); period 3, 2010-2019 (n = 51). RESULTS: Membranous nephropathy, nephrosclerosis, AA-amyloidosis, and IgA nephropathy were the four major renal manifestations of RA. AA-amyloidosis was diagnosed by kidney biopsy in 21 patients: period 1, 7 patients (15%); period 2, 10 patients (18%); and period 3, 4 patients (8%). The 4 patients in period 3 were in the years 2010-2014, and no new case of AA-amyloidosis was recorded from 2015 to 2019. In all 21 of the patients with AA-amyloidosis, neither a biologic agent nor methotrexate was administered. Fifteen of the 21 patients required dialysis, and 13 died in periods 1-3 because of amyloid-related cardiac dysfunction less than 2 years after the initiation of dialysis. Two of them are doing well using biologic agent despite dialysis. The remaining three patients who received a biologic agent or methotrexate does not progress to end-stage renal failure. In addition, the other renal complications showing progression to dialysis also decreased over time. CONCLUSION: Advances in treatment strategies have improved renal outcome and reduced mortality in patients with RA.

Retrospective analyses of other iatrogenic immunodeficiency-associated lymphoproliferative disorders in patients with rheumatic diseases.

Other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPDs) occur in patients receiving immunosuppressive drugs for autoimmune diseases; however, their clinicopathological and genetic features remain unknown. In the present study, we analysed 67 patients with OIIA-LPDs, including 36 with diffuse large B-cell lymphoma (DLBCL)-type and 19 with Hodgkin lymphoma (HL)-type. After discontinuation of immunosuppressive drugs, regression without relapse was achieved in 22 of 58 patients. Spontaneous regression was associated with Epstein-Barr virus positivity in DLBCL-type (P = 0·013). The 2-year overall survival and progression-free survival (PFS) at a median follow-up of 32·4 months were 92·7% and 72·1% respectively. Furthermore, a significant difference in the 2-year PFS was seen between patients with DLBCL-type and HL-type OIIA-LPDs (81·0% vs. 40·9% respectively, P = 0·021). In targeted sequencing of 47 genes in tumour-derived DNA from 20 DLBCL-type OIIA-LPD samples, histone-lysine N-methyltransferase 2D (KMT2D; eight, 40%) and tumour necrosis factor receptor superfamily member 14 (TNFRSF14; six, 30%) were the most frequently mutated genes. TNF alpha-induced protein 3 (TNFAIP3) mutations were present in four patients (20%) with DLBCL-type OIIA-LPD. Cases with DLBCL-type OIIA-LPD harbouring TNFAIP3 mutations had shorter PFS and required early initiation of first chemotherapy. There were no significant factors for spontaneous regression or response rates according to the presence of mutations. Overall, OIIA-LPDs, especially DLBCL-types, showed favourable prognoses.

Hypocalcemia and bone mineral changes in hemodialysis patients with low bone mass treated with denosumab: a 2-year observational study.

BACKGROUND: Increases in bone mineral density (BMD) following a single dose of denosumab and increased incidence of denosumab-associated acute hypocalcemia (DAAH) have been reported in chronic kidney disease patients. Little is known about clinical risk factors related to DAAH and the long-term effect of denosumab on BMD in hemodialysis patients. METHODS: An observational noncontrolled study involving 47 hemodialysis patients was conducted to determine the independent risk factors related to percentage changes in serum calcium (Ca) levels associated with denosumab using multivariate regression analysis. Optimal predictive markers for DAAH were explored by receiver operating characteristic analysis. Percentage changes of BMD at the lumbar spine (LS) and femoral neck (FN) at 24 months were investigated. RESULTS: The incidence of DAAH [serum corrected Ca (cCa) ≤8 mg/dL] following denosumab was 25.5%. Multivariate regression analysis showed that baseline bone alkaline phosphatase was independently related to percentage changes in cCa levels (ß = -0.407, P = 0.008). Tartrate-resistant acid phosphatase-5b was found to be the most accurate marker to predict DAAH, with an area under the curve of 0.750 (95% confidence interval 0.546-0.954; P = 0.02), and the optimal cut-off level was 670 mU/mL with sensitivity: 0.727 and specificity: 0.733. BMD significantly increased by 5.9 ± 1.7% (P = 0.01) at LS and 4.2 ± 1.5% (P = 0.04) at FN at 24 months. CONCLUSIONS: In hemodialysis patients, high bone turnover was an independent risk factor for the Ca declines induced by denosumab. Denosumab significantly increased BMD at LS and FN at 24 months.

Correcting anemia and native vitamin D supplementation in kidney transplant recipients: a multicenter, 2 × 2 factorial, open-label, randomized clinical trial.

Anemia and vitamin D deficiency are associated with allograft failure, and hence, are potential therapeutic targets among kidney transplant recipients (KTRs). We conducted a multicenter, two-by-two factorial, open-label, randomized clinical trial to examine the effects of anemia correction and vitamin D supplementation on 2-year change in eGFR among KTRs (CANDLE-KIT). We enrolled 153 patients with anemia and >1-year history of transplantation across 23 facilities in Japan, and randomly assigned them to either a high or low hemoglobin target (>12.5 vs. <10.5 g/dl) and to either cholecalciferol 1000 IU/day or control. This trial was terminated early based on the planned interim intention-to-treat analyses (α = 0.034). Among 125 patients who completed the study, 2-year decline in eGFR was smaller in the high vs. low hemoglobin group (i.e., -1.6 ± 4.5 vs. -4.0 ± 6.9 ml/min/1.73 m2 ; P = 0.021), but did not differ between the cholecalciferol and control groups. These findings were supported by the fully adjusted mixed effects model evaluating the rate of eGFR decline among all 153 participants. There were no significant between-group differences in all-cause death or the renal composite outcome in either arm. In conclusion, aggressive anemia correction showed a potential to preserve allograft kidney function.

Tocilizumab preserves renal function in rheumatoid arthritis with AA amyloidosis and end-stage kidney disease: Two case reports.

Case 1: A 59-year-old Japanese woman with rheumatoid arthritis (RA) for 36 years was admitted for evaluation of deteriorating renal function. Her serum creatine was 4.2 mg/dL, and proteinuria was 6.5 g daily. Renal and duodenal biopsy revealed AA amyloidosis. After treatment with tocilizumab (a humanized anti-interleukin-6 receptor antibody), proteinuria decreased to 1.1 g daily. The patient's renal function subsequently remained stable for 8 years. Case 2: A 71-year-old Japanese man with RA for 30 years was admitted due to deterioration of renal function. Serum creatine was 2.9 mg/dL, and urinary protein excretion was 0.06 g daily. Renal and duodenal biopsy identified AA amyloidosis. Tocilizumab was initiated, and his renal function remained stable for 6 years. The 2nd duodenal biopsy showed a marked decrease of AA amyloid deposits. Conclusion: These two cases suggest that tocilizumab may preserve renal function in the setting of end-stage kidney disease and shift the point of no return for RA patients with AA amyloidosis and renal dysfunction.

Syphilis-associated membranous nephropathy successfully treated with amoxicillin.

A 33-year-old Japanese man with no significant past medical history was admitted to our hospital for evaluation of weight gain and pitting edema. A laboratory test confirmed nephrotic-range proteinuria. Renal biopsy showed subepithelial deposits, and membranous nephropathy (MN) was diagnosed. Closer examination clarified an active syphilis infection. After renal biopsy, we prescribed amoxicillin for 8 weeks to treat the syphilis infection. Three weeks later, the patient's proteinuria dramatically decreased. This case is of interest because syphilis can become a cause of acute-onset MN in younger adults, and the incidence of syphilis is increasing in Japan.
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A case of thrombotic microangiopathy associated with polymyositis.

A 60-year-old Japanese woman with polymyositis (PM) developed hemolytic anemia (hemoglobin of 7.3 g/dL), thrombocytopenia (platelet of 9.1×104/µL), and acute kidney injury (Cre of 4.7 mg/dL) at 14 days after starting steroid therapy. Renal biopsy revealed glomerular endothelial swelling with fibrin thrombi and fragmented erythrocytes in the capillary lumens. Hemolytic uremic syndrome (HUS) with thrombotic microangiopathy (TMA) was diagnosed. Hemodialysis and plasma exchange/plasma transfusion were initiated, but HUS did not subside. After 45 days, the patient died of hemorrhagic respiratory failure. Autopsy showed fibrin thrombi filling the glomerular vascular pole and the small arteries in most glomeruli, resulting in glomerular collapse and glomerular basement membrane (GBM) duplication. Although renal involvement by PM is rare, HUS/TMA should be remembered as one of the serious renal complications of PM.

Validation of the diagnostic criteria for IgG4-related kidney disease (IgG4-RKD) 2011, and proposal of a new 2020 version.

BACKGROUND: In 2011, the IgG4-related kidney disease (IgG4-RKD) working group of the Japanese Society of Nephrology proposed diagnostic criteria for IgG4-RKD. The aim of the present study was to validate those criteria and develop a revised version. METHODS: Between April 2012 and May 2019, we retrospectively collected Japanese patients with kidney disease, for whom data on serum IgG4 values and/or immunohistological staining for IgG4 in renal biopsy samples were available. These patients were classified as IgG4-RKD or non-IgG4-RKD based on the diagnostic criteria for IgG4-RKD 2011, and the results were evaluated by expert opinion. Accordingly, we developed some revised versions of the criteria, and the version showing the best performance in the present cohort was proposed as the IgG4-RKD criteria for 2020. RESULTS: Of 105 included patients, the expert panel diagnosed 55 as having true IgG4-RKD and 50 as mimickers. The diagnostic criteria for IgG4-RKD 2011 had a sensitivity of 72.7% and a specificity of 90.0% in this cohort. Of the 15 patients with true IgG4-RKD who were classified as non-IgG4-RKD, all lacked biopsy-proven extra-renal lesions, although many had clinical findings highly suggestive of IgG4-RD. The revised version to which "bilateral lacrimal, submandibular or parotid swelling, imaging findings compatible with type 1 autoimmune pancreatitis or retroperitoneal fibrosis" was added as an item pertaining to extra-renal organ(s) improved the sensitivity to 90.9% while the specificity remained at 90.0%. CONCLUSION: The revised version has considerably improved test performance after addition of the new extra-renal organ item (imaging and clinical findings).

Factors predicting decline in renal function and kidney volume growth in autosomal dominant polycystic kidney disease: a prospective cohort study (Japanese Polycystic Kidney Disease registry: J-PKD).

BACKGROUND: Factors affecting decline in renal function and cyst growth in patients with autosomal polycystic kidney disease (ADPKD) are not fully described, particularly in Japan. METHODS: This was the first multi-facility, prospective, observational cohort study conducted in ADPKD patients at 14 centers in Japan. Patients in the J-PKD registry were assessed from December 2009 to June 2012 (follow-up until June 2017). Patients' data including estimated glomerular filtration rate (eGFR) and total kidney volume (TKV) were assessed initially and a maximum of five times annually. Contributing factors to eGFR decline and TKV growth were identified using multiple linear regression analysis. RESULTS: Of the 340 patients in the J-PKD registry, data analysis was performed for 192 patients in whom serial changes for both eGFR and TKV were obtained. eGFR slope, eGFR change, and TKV change values were as follows: - 2.7 (- 4.2 to - 1.5) (ml/min/1.73 m2/year), - 5.0 (- 9.6 to - 2.3) (%/year), and 4.78 (0.86-8.22) (%/year), respectively. Lower high-density lipoprotein (HDL) cholesterol was an independent predictor of eGFR decline, using both eGFR slope and change (P = 0.04, P = 0.02, respectively), whereas lower hemoglobin and higher uric acid were significantly associated with greater eGFR change only (P = 0.02, P = 0.002, respectively). Younger age and higher fasting blood sugar were independent predictors of greater TKV change (P = 0.01, P = 0.02, respectively). CONCLUSIONS: This real-world study in Japan identified risk factors for renal function decline in ADPKD patients. These included lower HDL cholesterol, lower hemoglobin and higher uric acid for eGFR decline, and youth and higher blood sugar levels for TKV growth.

Case report: Osteomalacia due to bisphosphonate treatment in a patient on hemodialysis.

BACKGROUND: No publications have reported on osteomalacia in patients receiving intermittent cyclical therapy with etidronate (a bisphosphonate) and undergoing long-term hemodialysis (HD). CASE PRESENTATION: We report on a 46-year-old Japanese man admitted to our hospital for further examination of left forearm pain. Maintenance HD was started at age 24 years, and the man had been on HD since then. At age 38 years, surgical parathyroidectomy was performed for secondary hyperparathyroidism; iliac crest bone biopsy performed at the same time showed osteitis fibrosa. The active vitamin D3 preparation calcitriol was started, and intermittent cyclical etidronate therapy was introduced 2 years later for osteoporosis. At age 45 years, the patient stopped taking calcitriol because of hypercalcemia but continued with etidronate. At age 46 years, a pseudofracture with a Looser zone occurred in the left ulna, and left femur bone biopsy revealed osteomalacia. Etidronate was discontinued, and calcitriol was restarted; open reduction and internal fixation with an angular stability plate were performed. Union of the bone was achieved 10 months after the operation. At age 49 years, a lumber bone biopsy confirmed improved bone morphometry. CONCLUSIONS: We believe that intermittent cyclical etidronate therapy without administration of active vitamin D3 during long-term HD might have induced osteomalacia, resulting in the ulna insufficiency fracture. Therefore, we propose that administration of active vitamin D3 is essential to prevent osteomalacia in patients on long-term HD who are receiving bisphosphonates and have potential vitamin D3 deficiency.

Significance of kidney biopsy in autosomal dominant tubulointerstitial kidney disease-UMOD: is kidney biopsy truly nonspecific?

BACKGROUND: Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare hereditary disease caused by a variety of genetic mutations. Carriers of a mutation in the responsible genes are at risk of reaching end-stage kidney disease typically in middle age. The frequency of this disease is assumed to be underestimated because of a lack of disease-specific signs. Pathological findings obtained from kidney of uromodulin related ADTKD (ADTKD-UMOD) patients are regarded as non-specific and less-informative for its diagnosis. This research was undertaken to evaluate the significance of kidney biopsy in ADTKD-UMOD patients. METHODS: Thirteen patients from 10 families with nine identified uromodulin (UMOD) gene mutations who underwent kidney biopsy in the past were studied. Their kidney tissues were stained with anti-UMOD antibody in addition to conventional methods such as PAS staining. When positive, the numbers of tubules with visible UMOD protein accumulations were calculated based on the total numbers of UMOD expressing tubules. Pathological findings such as tubulointerstitial fibrosis, atrophy, inflammation and glomerulosclerosis were also evaluated and analyzed. RESULTS: Interstitial fibrosis and tubular atrophy were present in all 13 patients. Most atrophic tubules with thickening and lamellation of tubular basement membranes showed negative UMOD staining. In all but two patients with C94F mutations, massive accumulation of UMOD proteins was observed in the renal endoplasmic reticulum. UMOD accumulations were also detectable by PAS staining as polymorphic unstructured materials in the 11 patients at frequencies of 2.6-53.4%. 80.4% of the UMOD accumulations were surrounded by halos. The detection rate of UMOD accumulations positively correlated with eGFR. Glomerulosclerosis was detected in 11/13 patients, with a frequency of 20.0 to 61.1%, while no cystic dilatations of glomeruli were detected. CONCLUSIONS: Massively accumulated UMOD proteins in ADTKD-UMOD kidneys are detectable not only by immunostaining using anti-UMOD antibody but also by conventional methods such as PAS staining, although their detection is not easy. These findings can provide important clues to the diagnosis of ADTKD-UMOD. Kidney biopsy in ADTKD-UMOD may be more informative than assumed previously.