Improvement of Light Chain Proximal Tubulopathy without Crystals in IgGλ-type Monoclonal Gammopathy of Undetermined Significance Using Bortezomib and Dexamethasone.

A 70-year-old woman with acute kidney injury, a high serum Creatinine (Cr) level (3.91 mg/dL), and proteinuria (protein/Cr ratio 1.59 g/gCr) was admitted. Serum IgG λ-type and urinary λ-type M proteins were observed. A bone marrow examination indicated monoclonal gammopathy of undetermined significance (MGUS). A renal biopsy showed distended proximal tubular cells, and immunofluorescence identified tissue positive for proximal tubular cell λ light chains. Electron microscopy identified fibril-like structures in the lysosomes. The patient was diagnosed with light chain proximal tubulopathy without crystals in IgG λ-type MGUS and treated with bortezomib and dexamethasone therapy, which improved her renal function.

Comparison of bone microstructures via high-resolution peripheral quantitative computed tomography in patients with different stages of chronic kidney disease before and after starting hemodialysis.

Chronic kidney disease (CKD) negatively affects bone strength; however, the osteoporotic conditions in patients with CKD are not fully understood. Moreover, the changes in bone microstructure between pre-dialysis and dialysis are unknown. High-resolution peripheral quantitative computed tomography (HR-pQCT) reveals the three-dimensional microstructures of the bone. We aimed to evaluate bone microstructures in patients with different stages of CKD. This study included 119 healthy men and 40 men admitted to Nagasaki University Hospital for inpatient education or the initiation of hemodialysis. The distal radius and tibia were scanned with HR-pQCT. Patient clinical characteristics and bone microstructures were evaluated within 3 months of initiation of hemodialysis (in patients with CKD stage 5 D), patients with CKD stage 4-5, and healthy volunteers. Cortical bone parameters were lower in the CKD group than in healthy controls. Tibial cortical and trabecular bone parameters (cortical thickness, cortical area, trabecular volumetric bone mineral density, trabecular-bone volume fraction, and trabecular thickness) differed between patients with CKD stage 5 D and those with CKD stage 4-5 (p < 0.01). These differences were also observed between patients with CKD stage 5 and those with CKD stage 5 D (p < 0.017), but not between patients with CKD stage 4 and those with CKD stage 5, suggesting that the bone microstructure rapidly changed at the start of hemodialysis. Patients with CKD stage 5 D exhibited tibial microstructural impairment compared with those with CKD stage 4-5. HR-pQCT is useful for elucidation of the pathology of bone microstructures in patients with renal failure.

An Autopsy Case of Disseminated Varicella Zoster Virus Infection during the Treatment of Nephrotic Syndrome.

A 68-year-old woman developed systemic blisters while receiving treatment for nephrotic syndrome. As she also developed marked liver dysfunction and disseminated intravascular coagulation, she was admitted to our hospital. She was diagnosed with varicella zoster virus (VZV) infection. Treatment was administered in the intensive-care unit, but the patient died on day 24 post-admission after severe VZV infection. A post-mortem examination showed micro-abscesses and necrosis caused by varicella zoster infection in multiple organs, including the liver, kidneys, and gastrointestinal tract. Because VZV infection can become severe in immunocompromised patients, careful consideration is needed for the prevention and treatment of the viral infection.

Association of Urinary Dickkopf-3 with Residual Renal Function Decline in Patients Undergoing Peritoneal Dialysis.

Background and Objectives: Urinary levels of dickkopf-3 (DKK-3) are associated with poor renal survival in patients with non-dialytic chronic kidney disease. However, it remains unknown whether urinary DKK-3 levels can predict residual renal function (RRF) decline in patients undergoing peritoneal dialysis (PD). Therefore, we investigated the correlation between urinary levels of DKK-3 and the subsequent rate of RRF decline in PD patients. Materials and Methods: This study included 36 PD patients who underwent multiple peritoneal equivalent tests during 2011-2021. The relationship between baseline clinical characteristics and the subsequent annual rate of Kt/V decline was investigated. Results: The annual rate of renal Kt/V decline was 0.29 (range: 0.05-0.48), which correlated with renal Kt/V (r = 0.55, p = 0.0005) and 24 h urinary DKK-3 excretion (r = 0.61, p < 0.0001). Similarly, 24 h urinary DKK-3 excretion (ß = 0.44, p = 0.0015) and renal Kt/V (ß = 0.38, p = 0.0059) were independently associated with the annual rate of renal Kt/V decline in multivariate analyses. Conclusions: Urinary DKK-3 assessment may help identify PD patients at a high risk of RRF decline.

Safety of Renal Biopsy by Physicians with Short Nephrology Experience.

Percutaneous renal biopsy is an essential tool for diagnosing various renal diseases; however, little is known about whether renal biopsy performed by physicians with short nephrology experience is safe in Japan. This study included 238 patients who underwent percutaneous renal biopsy between April 2017 and September 2020. We retrospectively analyzed the frequency of post-renal biopsy complications (hemoglobin decrease of ≥10%, hypotension, blood transfusion, renal artery embolization, nephrectomy and death) and compared their incidence among physicians with varied experience in nephrology. After renal biopsy, a hemoglobin decrease of ≥10%, hypotension and transfusion occurred in 13.1%, 3.8% and 0.8% of patients, respectively. There were no cases of post-biopsy renal artery embolism, nephrectomy, or death. The composite complication rate was 16.0%. The incidence of post-biopsy complications was similar between physicians with ≥3 years and <3 years of clinical nephrology experience (12.5% vs. 16.8%, p = 0.64). Furthermore, the post-biopsy composite complication rates were similar between physicians with ≥6 months and <6 months of clinical nephrology experience (16.3% vs. 15.6%, p > 0.99). Under attending nephrologist supervision, a physician with short clinical nephrology experience can safely perform renal biopsy.

Urinary Liver-Type Fatty Acid-Binding Protein Predicts Residual Renal Function Decline in Patients on Peritoneal Dialysis

BACKGROUND Liver-type fatty acid-binding protein (L-FABP) is a predictive marker for the early detection of acute kidney injury; however, less is known about how useful it is for predicting residual renal function (RRF) decline in patients on peritoneal dialysis (PD). MATERIAL AND METHODS The study subjects were 35 patients on PD who underwent multiple peritoneal equilibration tests (PETs) between October 2011 and October 2019. Urinary L-FABP levels were analyzed with enzyme-linked immunosorbent assay. The relationship between baseline clinical data, including urinary L-FABP levels and the subsequent annual rate of renal Kt/V decline, was investigated. RESULTS The median follow-up duration was 11 months and the rate of renal Kt/V decline was 0.29/y. Compared with outcomes in the group with renal Kt/V preservation, renal Kt/V decline was associated with both high daily levels of urinary protein excretion (0.60 g/d [range, 0.50-0.87] vs. 0.36 g/d [range, 0.19-0.48]; P=0.01) and high daily levels of urinary L-FABP excretion (111.2 mg/d [range, 76.1-188.6] vs. 61.5 mg/d [range, 35.7-96.0]; P=0.002). Multiple logistic regression analysis showed that only high daily levels of urinary L-FABP excretion were independently associated with renal Kt/V decline (odds ratio 1.03, 95% confidence interval 1.00-1.05; P=0.001). Furthermore, higher daily levels of urinary L-FABP excretion were significantly correlated with the higher annual rate of renal Kt/V decline (r=0.71, P<0.001). CONCLUSIONS We demonstrated that daily levels of urinary L-FABP are associated with RRF decline in patients on PD. The results of the present study indicate that assessment of urinary L-FABP levels may help predict RRF decline in patients on PD.

Risk Reduction for End-Stage Renal Disease by Dietary Guidance Using the Gustatory Threshold Test for Salty Taste.

Educational hospitalization of patients with chronic kidney disease (CKD) may slow the progression of renal dysfunction. However, the educational aspect that is more effective has not been identified to date. In this study, patients with CKD were evaluated for gustatory threshold for salty taste and received augmented salt reduction guidance under educational hospitalization at Nagasaki University Hospital from October 2016. In total, 277 eligible patients were enrolled and hospitalized from 2012 to 2019 (mean age of 69.2 years; men comprised 62.1%). We compared 141 patients (Group A) who were educated in the hospital after October 2016 and 136 patients (Group B) who received standard education in the hospital before October 2016. The changes in the estimated glomerular filtration rate (ΔeGFR) after hospitalization and dialysis induction rate within one year after hospitalization were evaluated. The ΔeGFR was significantly improved in Group A compared to Group B (A: 1.05 mL/min/1.73 m2/month, B: 0.55 mL/min/1.73 m2/month; p = 0.02). The dialysis induction rate was significantly lower in Group A than in Group B (A: 8.5%, B: 15.5%; p = 0.001). These trends were also observed by multivariate analyses. In conclusion, educational hospitalization with enhanced salt reduction guidance may reduce the risk of end-stage renal disease.

Transplantation of a kidney with a heterozygous mutation in the SLC22A12 (URAT1) gene causing renal hypouricemia: a case report.

BACKGROUND: Renal hypouricemia (RHUC) is a genetic disorder caused by mutations in the SLC22A12 gene, which encodes the major uric acid (UA) transporter, URAT1. The clinical course of related, living donor-derived RHUC in patients undergoing kidney transplantation is poorly understood. Here, we report a case of kidney transplantation from a living relative who had an SLC22A12 mutation. After the transplantation, the recipient's fractional excretion of UA (FEUA) decreased, and chimeric tubular epithelium was observed. CASE PRESENTATION: A 40-year-old man underwent kidney transplantation. His sister was the kidney donor. Three weeks after the transplantation, he had low serum-UA, 148.7 µmol/L, and elevated FEUA, 20.8% (normal: < 10%). The patient's sister had low serum-UA (101.1 µmol/L) and high FEUA (15.8%) before transplant. Suspecting RHUC, we performed next-generation sequencing on a gene panel containing RHUC-associated genes. A heterozygous missense mutation in the SLC22A12 gene was detected in the donor, but not in the recipient. The recipient's serum-UA level increased from 148.7 µmol/L to 231.9 µmol/L 3 months after transplantation and was 226.0 µmol/L 1 year after transplantation. His FEUA decreased from 20.8 to 11.7% 3 months after transplantation and was 12.4% 1 year after transplantation. Fluorescence in situ hybridization of allograft biopsies performed 3 months and 1 year after transplantation showed the presence of Y chromosomes in the tubular epithelial cells, suggesting the recipient's elevated serum-UA levels were owing to a chimeric tubular epithelium. CONCLUSIONS: We reported on a kidney transplant recipient that developed RHUC owing to his donor possessing a heterozygous mutation in the SLC22A12 (URAT1) gene. Despite this mutation, the clinical course was not problematic. Thus, the presence of donor-recipient chimerism in the tubular epithelium might positively affect the clinical course, at least in the short-term.

A case of membranoproliferative glomerulonephritis and AA amyloidosis complicated with pulmonary nontuberculous mycobacterial infection.

A 75-year-old man was diagnosed with pulmonary nontuberculous mycobacterial (NTM) infection in February 2005 and was treated with rifampicin, ethambutol, and clarithromycin. However, the infection was resistant to treatment, and his chest radiograph showed an abnormality that gradually seemed to aggravate. The patient's sputum was positive for Mycobacteria. Moreover, the patient had dyspnea and an underlying chronic inflammation in the lungs. He visited our hospital because of dyspnea and leg edema in June 2011. Laboratory evaluation on admission revealed proteinuria (6 g/day) and decreased serum total protein (5.8 g/dL) and albumin (1.6 g/dL) levels, indicating nephrotic syndrome. Percutaneous renal biopsy revealed membranoproliferative glomerulonephritis (MPGN) in the acute stage and AA amyloidosis of mild degree. AA amyloidosis was also diagnosed histologically on gastric and colonic biopsy, in addition to renal biopsy. His renal function decreased gradually, and therefore, he underwent hemodialysis therapy in January 2012. However, his gastrointestinal-related symptoms persisted, and his appetite diminished, because of which he had become severely malnourished; he died 8 months later. This is a rare case of a patient with two different renal lesions (MPGN and AA amyloidosis) complicated with NTM. Our case suggests that MPGN and amyloidosis should be considered in elderly patients with nephrotic syndrome onset and chronic inflammation.