Background: Diagnosis of membranoproliferative glomerulonephritis (MPGN) is based on kidney biopsy findings: unique glomerular injury pattern and characteristic changes on light, electron microscopy and immunohistochemical analysis. The purpose of this study was to identify possible etiology and incidence of glomerular injury among patients with a diagnosed MPGN.
Materials and methods: A retrospective analysis (years 2000-2014) of 81 clinical cases with a diagnosis of MPGN based on biopsy results was performed. Records were examined, and data about viral, bacterial infections, autoimmune and hematological diseases was collected. Test results of blood C3 and C4 factors of the complement system, and results of kidney biopsy immunohistochemical analysis were investigated. Statistical analysis was performed using Statistical Package for the Social Sciences and p-value less than 0.05 was considered statistically significant.
Results: Study population consisted of 55 males (67.9%) and 26 females (32.1%). The average patients' age was 48.53 (standard deviation ± 16.67) years. The identified etiology of MPGN was: idiopathic in 26 cases (32.10%), bacterial infections in 20 cases (24.69%), viral hepatitis in 16 cases (19.75%), autoimmune diseases in 11 cases (13.58%), and hematological diseases in eight cases (9.88%). Changes of the concentration of complement component C3 as well as component C4 were found; their concentration was decreased in 26 (32.1%) and 17 (20.99%) patients' respectively while concentration was within the normal range in 11 (13.58%) and 19 (23.46%) patients respectively. Immunohistochemistry results revealed immunoglobulin (Ig) deposits: C3+/Ig+ was found in 47 (58.02%) cases, C3-/Ig+ was found in 16 (19.75%) cases and in six (7.41%) cases test was not performed. The total number of immunoglobulin positive biopsies (C3+/Ig+ and C3-/Ig+, also called immune-complex mediated MPGN) was 63 (77.78%). Complement-mediated MPGN (C3+/Ig-) was less common and was diagnosed only in seven cases (8.64%). C3-/Ig- was found in five cases (6.17%).
Conclusions: The leading cause of MPGN was idiopathic as well as bacterial infections. Complement component C3 concentration was mostly decreased. The incidence of normal and decreased concentration of the complement component C4 was almost equal. Most immunohistochemical deposits in kidney biopsy appeared to be C3/Ig positive, and it was observed in more than half of the cases of each MPGN etiological group. Hippokratia 2015; 19 (4): 314-318.
Keywords: Membranoproliferative glomerulonephritis; complement system; immunohistochemistry; kidney biopsy.