Differentials
IgA vasculitis (previously known as Henoch-Schönlein purpura [HSP])
SIGNS / SYMPTOMS
Characterised by the presence of systemic symptoms, including purpuric rash (90% of cases); abdominal pain (85% of cases); joint pain (70% of cases); peripheral oedema; and GI bleeding.
INVESTIGATIONS
There are no tests to differentiate IgA vasculitis nephritis from IgA nephropathy as histopathological findings are similar.[9] The histological evidence of extra-renal vasculitis (e.g., skin or GI tract) will point to a diagnosis of IgA vasculitis.
Thin glomerular basement membrane disease
SIGNS / SYMPTOMS
Visible haematuria may occur.[8]
Proteinuria rare.
Does not usually progress to end-stage kidney disease.
INVESTIGATIONS
Under electron microscopy the basement membranes appear diffusely thin and there is no mesangial expansion under light microscopy.
Immunofluorescence is negative for IgA .[8]
Alport's syndrome
SIGNS / SYMPTOMS
Visible haematuria may occur.
Proteinuria common.
Family history of kidney failure, primarily in males.
Sensorineural hearing loss and ocular abnormalities.[8]
INVESTIGATIONS
Electron microscopy shows longitudinal splitting and thickening of the lamina densa of the glomerular basement membrane.
In addition, alpha 3, alpha 4, and alpha 5 chains of type IV collagen are absent in the basement membrane.
Post-streptococcal glomerulonephritis
SIGNS / SYMPTOMS
Visible haematuria occurs 1 to 3 weeks after the onset of streptococcal infection.
Hypertension and oedema frequently occur.
Recurrent haematuria is not characteristic.
INVESTIGATIONS
Elevated levels of antibodies to streptococcal antigens (anti-streptolysin O or anti-DNase B) are a good diagnostic clue.
C3 is usually low in the first 2 weeks of infection.
Systemic lupus erythematosus (SLE)
SIGNS / SYMPTOMS
Extra-renal manifestations of SLE (such as discoid skin rash, joint pain and swelling, oral ulcers, and alopecia) may be present.
INVESTIGATIONS
Autoimmune serology, such as anti-nuclear antibody and anti-double stranded DNA, may be present and C3 and C4 is usually low in severe proliferative lupus nephritis.
Light microscopy features vary widely but patients with severe lupus nephritis demonstrate diffuse proliferative lesions.
Immunofluorescence shows a 'full-house' picture (positive for IgA, IgM, IgG, C3, C4, C1q, and kappa and lambda light chains).
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