Diagnosis of pMN is made by kidney puncture, histological examination and electron microscopy of the kidney tissue. Characteristic here is the deposition of immunocomplexes on the outside of the glomerular basement membrane. Serological diagnosis of pMN, however, is less time-consuming and less stressful for the patient. The identification and characterisation of PLA2R and THSD7A as target antigens of circulating antibodies in pMN has proven to be of major importance for non-invasive diagnostics. Autoantibodies of class IgG against PLA2R are highly specific and can be found in the serum of up to 80% of patients with pMN. In contrast they are not exhibited by healthy blood donors or patients with secondary MN. In healthy persons and patients with secondary MN, these autoantibodies are not present. Reported prevalences for autoantibodies against THSD7A range up to 10%. Even though both antibodies can occur in parallel, anti-THSD7A antibodies are mainly found in anti-PLA2R-seronegative pMN patients. As a supplement to anti-PLA2R antibodies, anti-THSD7A antibodies are therefore another marker in the serological diagnosis of pMN. Due to their high specificity, they are equally suited for differentiation from secondary MN as anti-PLA2R antibodies.

The three methods IIFT, ELISA and ChLIA are available for the determination of autoantibodies against PLA2R. The IIFT allows a qualitiative to semiquantitative determination of human IgG autoantibodies against PLA2R, whilst the ELISA and ChLIA allow reliable quantification. The anti-PLA2R titer helps to assess the success of therapeutic measures. The serological finding with increase, decrease or disappearance of the antibody titer precedes the clinical image. Thus, the determination of the autoantibody titer has a high predictive value with respect to clinical remission or relapse and estimation of the risk of pMN reoccurence after kidney transplantation.

The Anti-THSD7A IIFT is an ideal supplementary test to the anti-PLA2R test systems. The serological detection rate is increased with parallel determination or a two-step screening strategy in which patients with a seronegative anti-PLA2R result are additionally investigated for anti-THSD7A antibodies.