Discrimination between postinfectious IgA-dominant glomerulonephritis and idiopathic IgA nephropathy

Figures & data

TABLE 1.  Demographic and clinical features of patients with postinfectious IgA-dominant glomerulonephritis

No. of patients	12
Age (years), mean ± SD	62 ± 17 (range 23–80)
Gender (M/F)	9/3
Diabetes	1
Hematuria, fraction of patients (%)	12/12 (100)
Macrohematuria, fraction of patients (%)	4/12 (33.3)
Proteinuria (g/24 h), mean ± SD	3.9 ± 3.2 (range 0.4–9.8)
Serum creatinine at the time of biopsy (mg/dL), mean ± SD	5.0 ± 3.5 (range 0.6–11.8)
Acute renal failure at presentation, fraction of patients (%)	10/12 (83.3)
Decreased serum complement levels, fraction of patients (%)	7/12 (58.3)
Increased serum IgA levels, fraction of patients (%)	6/9 (66.7)
Infectious agents
Methicillin-resistant Staphylococcus aureus	3
Methicillin-sensitive Staphylococcus aureus	3
Methicillin-sensitive Staphylococcus epidermidis	1
Streptococcus	2
Klebsiella pneumoniae	1
Escherichia coli	1
Acinetobacter baumannii	1

TABLE 2.  Histological features of patients with postinfectious IgA-dominant glomerulonephritis

No. of biopsies	12
% globally sclerotic glomeruli, mean ± SD	16 ± 11% (range 0–36%)
Pattern of glomerular hypercellularity
Diffuse endocapillary and mesangial proliferation	2
Diffuse endocapillary proliferation	2
Diffuse mesangial proliferation	1
Focal mesangial proliferation	7
Glomerular neutrophil infiltration, fraction of patients (%)	5/12 (42)
Glomerular crescents, fraction of patients (%)	4/12 (33)
Glomerular necrosis, fraction of patients (%)	2/12 (17)

FIGURE 1. Immunofluorescence staining for IgA in a patient with diffuse endocapillary proliferative glomerulonephritis shows 2+ granular deposition in predominantly glomerular capillary loops (original magnification ×400); there is also 2+ staining for C3 in a similar pattern (not shown).

FIGURE 2. Electron microscopy shows large subepithelial hump-shaped electron dense deposition (original magnification × 8000).

TABLE 3.  Comparison of clinicopathological parameters between postinfectious IgA-dominant glomerulonephritis and idiopathic IgA nephropathy

Variables	Postinfectious IgA-dominant glomerulonephritis (n = 12) Mean ± SD or No. (%)	Idiopathic IgA nephropathy (n = 134) Mean ± SD or No. (%)	p-Value
Clinical parameters
Age (years)^a	62.3 ± 16.9	37.9 ± 16.3	<0.001*
Gender (male/female)^b	9/3	69/65	0.141
Hematuria (score)^a	4 ± 0	2.0 ± 1.5	<0.001*
Macroscopic hematuria^b	4 (33.3)	18 (13.4)	0.085
Proteinuria (g/24 h)^a	3.9 ± 3.2 (n = 9)	2.8 ± 3.7 (n = 133)	0.135
Decreased serum complement^b	7/12 (58.3)	5/95 (5.3)	<0.001*
Increased serum IgA^b	6/9 (66.7)	36/108 (33.3)	0.068
Serum creatinine at the time of renal biopsy (mg/dL)^a	5.0 ± 3.5	2.2 ± 2.6	<0.001*
Acute renal failure at presentation^b	10 (83.3)	14 (10.4)	<0.001*
Histological parameters
Glomerular cellularity (score)^a	2.2 ± 0.8	1.7 ± 0.8	0.063
Endocapillary proliferation^b	4 (33.3)	1 (0.7)	<0.001*
Glomerular neutrophil infiltration^b	5 (41.7)	2 (1.5)	<0.001*
Glomerular crescent formation^b	4 (33.3)	29 (21.6)	0.469
C3 positive staining on IF^b	12 (100)	101 (75.4)	0.069
Mesangial staining on IF^b	8 (66.7)	134 (100)	<0.001*
Capillary loop staining on IF^b	6 (50.0)	3 (2.2)	<0.001*
Subepithelial electron-dense deposits on EM^b	5 (41.7)	1 (0.7)	<0.001*

Notes: IF, immunofluorescence; EM, electron microscopy.

^aData were analyzed by Mann-Whitney U-test.

^bData were analyzed by Fisher's exact test.

*p-Value < 0.05.