Canadian Journal of Kidney Health and Disease最新文献

Objective: Monoclonal gammopathy of renal significance (MGRS) is a heterogeneous and relatively recently defined disorder that encompasses many kidney and hematologic pathologies. MGRS remains a rare disease and there is a need for more literature regarding its treatment and outcomes. In this study, we share our center's experience with MGRS including incidence of different kidney pathologies, clone type, kidney and hematologic response, and progression-free survival.

Methods: Data from 35 patients diagnosed with MGRS excluding light-chain amyloidosis between 2013 and 2022 at a single Canadian tertiary care center were retrospectively analyzed. All cases required kidney biopsy. Initial treatment included regimens containing bortezomib, rituximab, or cyclosporine, or steroids only. Parameters studied included incidence of different kidney pathologies, clone type, depth of hematologic response, kidney survival (KS), overall survival (OS), and progression-free survival (PFS).

Results: Out of 35 patients, there were 10 cases of monoclonal immunoglobulin deposition disease, 8 of proliferative glomerulonephritis with immune deposits, 5 of microtubular immune deposits including immunotactoid and types 1 and 2 cryoglobulinemic nephropathy, 3 of C3 glomerulonephritis, and 9 of other diagnoses. There were 21 cases with a plasma cell clone identified in bone marrow, 2 each of B cell and low-grade lymphoma, 1 atypical T cell clone, and 9 cases without an expanded clone on bone marrow biopsy. A total of 6 patients required kidney replacement therapy and 4 patients died; the median PFS was 59.3 months. Very good partial hematologic response or better was significantly associated with decreased proteinuria but not preserved eGFR. There was a non-significant trend toward better PFS with hematologic response.

Conclusion: Our experience confirms that MGRS is a heterogeneous disease and adds to the literature concerning the diagnosis and treatment of MGRS. Successful treatment of the underlying hematologic disorder with targeted therapy is more likely to lead to an improvement in kidney function.

Rationale: Albuminuria is a commonly used parameter for predicting decline in kidney filtration function. Cubilin, encoded by CUBN, is a critical protein involved in protein reabsorption in the proximal tubule. Mutations in CUBN lead to Imerslund-Gräsbeck syndrome (IGS), a disorder characterized by vitamin B12 deficiency (and consequences related to that) with or without albuminuria. Recent evidence suggests that C-terminal variants in CUBN may lead to albuminuria without other features of IGS.

Presenting concerns of the patient: Here, we report a case of a 52-year-old male with chronic, albumin-predominant, subnephrotic range proteinuria since his teenage years, but preserved estimated glomerular filtration rate (eGFR).

Interventions: Neither angiotensin-converting enzyme (ACE) inhibition nor angiotensin Type II (AT-II) receptor blockade reduced his degree of albuminuria.

Diagnosis: Genetic testing identified 3 distinct pathogenic variants in CUBN that were confirmed by segregation analysis to be a compound heterozygous mode of inheritance. All variants were downstream of the intrinsic factor-vitamin B12 binding domain of cubilin. The patient had normal vitamin B12 levels and did not exhibit any features of IGS.

Outcomes: Kidney biopsy was not pursued for this patient as diagnostic clarification was achieved by non-invasive genetic testing alone.

Novel findings: This case highlights several important lessons. First, not all albuminuria is made equal, and forms of tubular albuminuria can exist without compromising kidney filtration function. Second, identifying genetic forms of tubular albuminuria is key to avoiding ineffective interventions (eg, ACE inhibition, AT-II receptor blockade, sodium-glucose cotransporter-2 [SGLT2] inhibition) and unnecessary invasive procedures (eg, kidney biopsy). Third, the location of CUBN variants dictates phenotypic consequences, with C-terminal variants leading to albuminuria without vitamin B12 deficiency.

Background: The COVID-19 pandemic and its accompanying safeguards intensified many of the ongoing daily challenges faced by caregivers of young people with chronic kidney disease (CKD) both pre-transplant and post-transplant, and also created a variety of new and pressing concerns. Little is known about how these families managed this unexpected adversity in their lives.

Objective: To evaluate change in psychosocial risk for families of young people with CKD during the COVID-19 pandemic health emergency from the perspective of caregivers.

Design: A short-term longitudinal mixed-methods study with a convergent parallel design.

Setting: Manitoba, Canada.

Participants: Thirty-six caregivers of young people with CKD participated in a quantitative assessment prior to the pandemic; approximately half were transplant recipients. Thirteen were re-assessed during the pandemic (62% were caregivers of transplant recipients) using both qualitative and quantitative assessments.

Methods: First, caregivers completed the Psychosocial Assessment Tool (PAT) prior to the pandemic. Second, caregivers were re-assessed using the PAT during the pandemic. They were also interviewed about their experiences. Changes in PAT scores over time were evaluated, including an investigation of whether psychosocial risk was related to transplant status. Interviews were coded using thematic analysis. In the interpretation stage, the qualitative findings were combined with the quantitative results to help explain the latter and reach a more fulsome understanding of caregivers' experience.

Results: Quantitatively, overall family psychosocial risk scores increased significantly during the pandemic health emergency, as did the domain of Caregiver Problems. Families of transplant recipients were found to be at significantly lower psychosocial risk pre-pandemic than families of transplant candidates. Coding identified Negative Pandemic Experiences, Positive Pandemic Experiences, and Coping Mechanisms. Mixed-methods analyses revealed several areas of convergence and divergence between the quantitative and qualitative findings.

Limitations: Limitations included a small sample size that limited generalizability, single site data collection, and single caregiver report.

Conclusions: Although overall family psychosocial risk increased during the pandemic, caregivers described several resilience processes and characteristics. A mixed-method approach provided a unique perspective that highlighted the value of integrating quantitative and qualitative findings. Results were discussed within the pediatric psychosocial preventive health model framework.