Diagnosis of MN is mainly based on results from kidney biopsies. The collected tissue is investigated by microscopy and in the case of a positive result, it shows the typical deposits in the kidney. However, biopsy is an invasive procedure and is both a physical and psychological burden for the patient.
The discovery of specific autoantibodies against PLA2R and THSD7A enabled more gentle diagnostics by means of simple blood tests, which also allow for monitoring of the disease course over a longer time period. Currently, four standardised test systems approved for pMN diagnostics are available.
They are all based on the detection of autoantibodies against PLA2R and THSD7A in the blood of the patient by means of either a fluorescence reaction (in indirect immunofluorescence test, IIFT), a colour reaction (in the ELISA) or a chemiluminescence reaction (in the chemiluminescence immunoassay, ChLIA).
Using the ELISA or the ChLIA, even the exact amount of antibodies can be measured, which allows the disease activity to be determined.
The analyses are nowadays offered by many laboratories and specialised centres. A reliable test result is often already available within only a few hours after blood withdrawal.