Back
Membranoproliferative glomerulonephritis (MPGN) is classified into 2 entities: immune complexes associated (IC-MPGN) and those mediated by C3 (C3G), according to immunofluorescence. A group of the first one are idiopathic. Both have similar physiopathological mechanisms, such as antibodies or genetic disorders.
We retrospectively analyzed cases at Hospital Italiano de Buenos Aires with one of these diagnoses, between 2010 and 2022. We analyzed the following variables: age, sex, comorbidities, main manifestation, proteinuria, hematuria, serum creatinine, seric albumin, seric C3 and C4, histologic findings, treatments, kidney outcomes
Of the 32 cases, 13 (40.6%) were C3G and 19 (59.4%) IC-MPGN. Of this, 10 patients had a second biopsy, and 2 were reclassified 2 in the other entity.
The median age of patients with IC-MPGN and G3C was 57.6 and 40.6 years respectively (p 0.004). The main manifestation in patients was nephrotic syndrome (40.6%), chronic kidney disease (31.3%), nephritic syndrome (12.5%), isolated hematuria (12.5%) and only 1 patient was classified as rapidly progressive kidney failure. Proteinuria was found in 90.6% of cases, while hematuria was found in 56.3%. The degree of proteinuria was not associated with the type of disease (mean of 4.22 g/24 hours ± 4.13 in C3G vs 4.57 g/24 hours ± 3.33 in IC-MPGN), but hypoalbuminemia was significantly lower in the IC-MPGN group 2.76 g% ± 0.73 vs 3.69 g% ± 0.72 in those with C3G. Serum C3 levels were below normal in 51.6% of patients. When compared to IC-MPGN patients, C3G patients had significantly lower levels (70.6 mg/dL ± 39.7 vs 100.8 mg/dL ± 33.3, p 0.029). Out of the 4 patients we analyzed, 3 had a genetic disorder (H-factor or related proteins). In histology we found duplication of the basement membrane in 66.7% of cases, crescents in 28.1% and immunoglobulin deposits in 75%.
As treatment, patients received blockade of the renin angiotensin system in 75% of cases, and half received immunosuppressive therapy. During the observational period, 28.1% developed end stage chronic kidney disease, 25% were lost to follow-up, 15.6% had stable renal function and only 2 patients underwent transplantation.
This retrospective study is the first series of cases reported in Argentina on this pathology and its relationship. Our C3G population is older than reported in other studies but still is younger than IC-MPGN patients. There is a trend that IC-MPGN patients debuted as nephrotic syndrome more likely, meanwhile, C3G patients are varied. Serum C3 values are low in similar proportions, but lower in C3G cases. Life courses in both entities were similar.