Relationship between serum IgA/C3 ratio and progression of IgA nephropathy.
OBJECTIVE
The serum IgA/C3 ratio might be considered to serve as a diagnostic marker for patients with IgA nephropathy (IgAN), but its value as a marker of the severity of histological lesions or prognosis is unknown.


METHODS
We studied the serum IgA/C3 ratio, using standardized reference material, in 86 patients with IgAN and in 32 with non-IgAN. The patients with IgAN were divided according to the severity of histological lesions (mild IgAN, n=29 and severe IgAN, n=57) based on Japanese clinical guidelines.


RESULTS
The serum IgA level was significantly higher, while its C3 level was lower in patients with severe IgAN compared to those with non-IgAN. However, these levels were not different between patients with mild IgAN and non-IgAN. In contrast, the serum IgA/C3 ratio obviously differed among the three groups (2.47+/-0.96 vs. 3.63+/-1.44 vs. 4.72+/-1.86; p<0.01, ANOVA). Kaplan-Meier analysis of the patients with IgAN classified according to the mean serum IgA/C3 ratio revealed that the group with high serum IgA/C3 (4.5 and above) had a significantly poorer renal outcome (p<0.05, log-rank test), since the cumulative renal survival rate at 5 years was 84.4% vs. 100%. The ratio (%) of patients with severe IgAN in whom hematuria disappeared, was significantly higher in the low, than in the high serum IgA/C3 group (41.9% vs. 15.4%; p<0.05, t-test).


CONCLUSIONS
The serum IgA/C3 ratio appears to reflect the histological severity of IgAN and could serve as a marker of the progression of IgAN.
Komatsu
Hiroyuki
H
First Department of Internal Medicine, Miyazaki Medical College, University of Miyazaki, Miyazaki.
Fujimoto
Shouichi
S
Hara
Seiichiro
S
Sato
Yuji
Y
Yamada
Kazuhiro
K
Eto
Tanenao
T
D000328:Adult; D003176:Complement C3 / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D005922:Glomerulonephritis, IGA / Q000097:blood* / Q000503:physiopathology; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007677:Kidney Function Tests; D007678:Kidney Glomerulus / Q000473:pathology; D008297:Male; D011379:Prognosis; D016019:Survival Analysis
D003176:Complement C3; D007070:Immunoglobulin A