Investigations
1st investigations to order
urinalysis
Test
Not sensitive or specific for IgAN. Similar findings in other kidney diseases.
Result
erythrocyturia, proteinuria (usually <2-3 g/day)
urine microscopy and culture
Test
Required to exclude a urinary tract infection as a cause of persistent haematuria or proteinuria.
Result
dysmorphic erythrocytes, rarely red cell casts, no bacterial growth
basic biochemistry, including estimated glomerular filtration rate (GFR)
Test
Ordered routinely to monitor kidney function and disease progression.
Not sensitive or specific for IgAN.
Result
usually normal in cases of isolated invisible haematuria; risk of reduced estimated GFR increases with increasing proteinuria
C3 and C4 complement levels
Test
Ordered to exclude other immune complex nephropathies.
Result
normal
kidney ultrasound
Test
Should be performed in patients with persistent urinary abnormalities to exclude structural kidney abnormalities.
Result
normal
computed tomography (KUB)
Test
Computed tomography of kidney, ureter, bladder (KUB) may also be considered in patients with persistent urinary abnormalities to exclude structural kidney abnormalities.
Result
normal
kidney biopsy
Test
Absolute requirement to make a diagnosis of IgAN.
Indications vary from centre to centre.
Result
diffuse mesangial IgA deposition
Investigations to consider
flexible cystoscopy
Test
Should be considered in all patients >40 years with persistent haematuria to exclude a transitional cell carcinoma.
Result
normal
skin biopsy
Test
Performed in those cases where IgA vasculitis (previously known as Henoch-Schönlein purpura [HSP]) is suspected.
Skin biopsy has no role in diagnosing IgAN.
Result
evidence of capillary deposits of IgA, C3, properdin, and fibrin
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