Diagnostic tests for Membranoproliferative glomerulonephritis
What is the appropriate workup for patients with Membranoproliferative glomerulonephritis ?
The critical laboratory test that suggests the diagnosis of MPGN is hypocomplementemia—namely, reduced C3 and CH50 levels, which are confirmed in 80% to 90% of cases.
The C4 and factor B levels are also low in approximately 40% of those with type I Membranoproliferative glomerulonephritis.
This is less common in those with type II or III Membranoproliferative glomerulonephritis.
Molecular markers of activation of the alternative pathway of complement, such as Bb and C3d, are elevated in patients with type II Membranoproliferative glomerulonephritis.
Measurement of all components of the complement cascade to distinguish between the different types of Membranoproliferative glomerulonephritis is usually not performed in clinical chemistry laboratories and currently is available only in select research facilities.
Activity of C3 nephritic factor, an IgM autoantibody that stabilizes C3 convertase, should be assayed in all forms of primary and secondary Membranoproliferative glomerulonephritis.
In adults with cryoglobulinemia, testing should be performed for hepatitis B and C infection.
Hepatitis serology should be evaluated in pediatric patients with Membranoproliferative glomerulonephritis even in the absence of mixed cryoglobulinemia.
Other laboratory abnormalities will be present depending on the underlying disease.
The confirmatory test in patients with hypocomplementemia or a suggestive history is a kidney biopsy demonstrating the characteristic histopathological findings.
