Biopsies in Renal Transplant Patients With Proteinuria: Histological Findings

Transplant kidney biopsy for proteinuria with stable creatinine: Findings and outcomes

INTRODUCTION

Little is known aboutbiopsy findings and outcomes when kidney transplant recipients (KTRs) undergo biopsy for isolated proteinuria with stable serum creatinine (SCr).

METHODS

We analyzed all KTRs who underwent biopsy for isolated proteinuria with stable SCr between January 2016 and June 2020. Patients were divided into three groups based on the biopsy findings: Active Rejection (AR), Glomerulonephritis (GN), and Other.

RESULTS

A total of 130 KTRs fulfilled our selection criteria; 38 (29%) in the AR group, 26 (20%) in the GN group, and 66 (51%) in the Other group. Most baseline characteristics were similar between the groups. In multivariate analysis, higher HLA mismatch (HR per mismatch: 1.30; 95% CI:1.06-1.59; P = .01) and male gender (HR: .45; 95% CI .23-.89; P = .02) were associated with AR. There was no significant correlation between the degree of proteinuria and rejection (r = .05, P = .58) or GN (r = .07, P = .53). Graft survival was also similar between the groups. Likely due to the early diagnosis without a significant rise in SCr, outcomes were similar among all three groups.

CONCLUSION

Routine monitoring for proteinuria followed by a biopsy and appropriate management may help to identify early acute graft injury and prevent graft failure.

Prevalence and Causes of Proteinuria in Kidney Transplant Recipients: Data from a Single Center

Introduction. Proteinuria after renal transplantation increases the risk of graft failure and mortality. The aim of the study was to determine the prevalence and causes of proteinuria in kidney transplant recipients. Methods. All kidney transplant recipients followed up in our clinic were included in the study. As a center protocol 24-hour urine collections were used to quantify protein excretion with 3-month intervals posttransplantation during the first year, and yearly thereafter. The etiology of chronic kidney disease and demographic characteristics of the study group were obtained from outpatient records. Data regarding the immunosuppressive regimens used, 24-hour proteinuria levels and creatinine clearences, new-onset hypertension, new-onset diabetes mellitus, rejection episodes, infections like cytomegalovirus (CMV) and polyoma (BK), and biopsy findings were noted. Results. A total of 260 kidney transplant recipients (97 females, mean age 42.3±12.3 years) were evaluated. Median follow-up period was 36 months; 137 of all transplantations were from living donors. Mean age of donors was 42.7±15 years and 133 were female. Proteinuria with protein excretion ≥300 mg/d was present in 35.4% of patients. The most common cause of biopsy-proven proteinuria was transplant-specific conditions (acute rejection, and borderline changes). Conclusion. The prevalence of proteinuria was 35.4%. The transplant-specific diagnoses were the most likely causes. Even in nonnephrotic ranges it was associated with decreased graft survival.

Change in glomerular volume and its clinicopathological impact after kidney transplantation

BACKGROUND

Both immunological and non-immunological etiologies affect graft function after kidney transplantation, including acute rejection, calcineurin inhibitor toxicity, and a recurrence of glomerulonephritis. Glomerular enlargement or glomerular sclerosis due to glomerular hyperfiltration related to increased renal blood flow is another cause. Although the glomerular volume in baseline biopsies predicts late allograft function, the relationship between allograft function and the annual changes in glomerular volume after kidney transplantation are unclear.

AIM

We investigated changes in glomerular volume after kidney transplantation and their clinicopathological relationship.

METHODS

We enrolled 23 patients with stable kidney function without an episode of rejection or any complication resulting in a functional decrease in the graft. We measured glomerular volume (GV) using the Weibel-Gomez method and glomerular density (GD) using 0,1 h biopsy samples as baseline controls and 1 yr biopsy samples and investigated the association between the changes in them and clinical parameters, including graft function, proteinuria, and renal hemodynamic markers, including effective renal plasma flow (ERPF) and filtration fraction (FF). The ERPF was calculated from a 99mTc-mercaptoacetyltriglycine (MAG3) renogram.

RESULTS

The GV and ERPF increased significantly 1 yr after kidney transplantation. In contrast, proteinuria decreased significantly and Δproteinuria (1 yr - 1 month after transplantation) was correlated with ΔGV (P < 0.05, rs  = -0.467).

CONCLUSION

Glomerular enlargement 1 yr after transplantation may be related to improved proteinuria. It is possible that glomerular enlargement serves as a renal adaptation after kidney transplantation.

De novo lupus nephritis in a renal transplanted child: a case report

De novo lupus nephritis (LN) is a rare complication in renal transplantation recipients. We present the clinical manifestations of de novo LN in a 12-year-old boy who received a cadaveric renal transplant. The cause of end-stage renal disease was prune belly syndrome with renal dysplasia. His immunosuppressive drugs included tacrolimus, mycophenolate sodium, and prednisolone. After 3 years of treatment, he developed nephrotic syndrome (NS) without other symptoms of systemic lupus erythematosus (SLE). The renal pathology of the transplanted kidney showed suspicious acute cellular rejection and LN World Health Organization class IV-G (A/C). Antinuclear antibody was positive, but anti-dsDNA and anti-Smith were negative. The serum complements were initially normal. Pulse methylprednisolone was given and the dosages of all immunosuppressive drugs increased; notwithstanding, his edema and hypoalbuminemia worsened. Repeated biopsy of the transplanted kidney was done. A full-house pattern was documented under immunofluorescent examination which confirmed LN WHO class IV-G (A/C) without evidence of rejection. He then developed macrophage-associated hemophagocytic syndrome and cytomegalovirus pneumonia. He ultimately developed pulmonary hemorrhage and died owing to severe pneumonia. De novo LN should be considered in renal transplant recipients with new onset of NS despite there not being any other clinical manifestations of SLE.