LAUSR

Antibody to phospholipase A2 receptor (PLA2R) was widely detected for a decade as a diagnostic marker of idiopathic membranous nephropathy. Recently, several studies reported that a lower cut-off of serum PLA2R antibody (PLA2RsAb) could improve diagnostic efficacy. The recommend cut-off ranged from 2.0 to 2.7 RU/ml which was considered largely improving the sensitivity of the assay. Other reported that although sensitivity of the measurement might loss to some extent cut-off at 14 RU/ml might of the best clinical performance. However, the lower cut-off was slightly higher than the minimum detection limit, that was 2.0 RU/ml. There was no study evaluated the test efficiency of low titer antibody of the measurement. The reference range of PLA2RsAb was validated by testing 40 serum from health volunteer, male/female ratio was 20/20. The samples for intra and inter-batch precision test were prepared by mixing low titer PLA2RsAb serum. The intra-batch precision was performed by repeating six times of the validation sample in one plate. The inter-batch precision was performed by repeating four times of validation samples in one plate on five days. The medium age of male was 34 (31, 53) and 46 (31, 54) for female, respectively. PLA2RsAb was ranged from 2.0 to 4.3 RU/ml for male and 2.0 to 4.0 RU/ml for female. The average of intra-batch validation sample was 8.1 ± 1.2 RU/ml. The intra-batch precision was presented by coefficient of variation, that was 15%. The average of inter-batch validation samples were 4.0 ± 0.4 RU/ml and 5.2 ± 0.5 RU/ml, respectively. The inter-batch precision was 10% for both validation serum. Healthy population showed low titer PLA2RsAb positive according to a lower cut-off. The validation showed relative high coefficient of variation on intra and inter-batch precision of low titer PLA2RsAb.