Specimen Requirements

Alternate Specimen Requirements

Minimum Specimen Requirements

Stability

Days Performed

Mon, Wed, Fri

Turnaround Time

4 - 8 days

Methodology

Special Info

Reflex Algorithm: The phospholipase A2 receptor (PLA2R) enzyme-linked immunosorbent assay (ELISA) is initially performed. If the PLA2R ELISA result is greater than 20 (positive), no additional testing will be performed. If the PLA2R ELISA result is less than 20 (negative or borderline), then the reflex test PLA2R immunofluorescence (PLA2RI) will be performed at an additional charge. If the reflex PLA2R immunofluorescence result is positive, no additional testing will be performed. If the reflex PLA2R immunofluorescence result is negative, the reflex test thrombospondin type-1 domain-containing 7A (THSD7A) antibody testing will be performed at an additional charge. This test is New York DOH approved.

Clinical Info

This test is useful in distinguishing primary membranous nephropathy (pMN) from secondary membranous nephropathy (sMN), monitoring patients with MN at very low antibody titers, and screening for anti-phospholipase A2 receptor antibodies. Anti-phospholipase A2 receptor (PLA2R) antibodies are highly specific for the diagnosis of pMN. As many as 70% to 75% of patients with pMN are positive for anti-PLA2R. A titer increase, decrease, or disappearance generally precedes a change in clinical status. MN is a rare disease in which immune complexes deposit at the glomerular basement membrane, causing damage to the filtration barrier, resulting in proteinuria. Recent studies have shown that in approximately 70% of patients with pMN, the immune complexes consist of autoantibodies against the podocyte protein M-type PLA2R. There is also evidence that levels of anti-PLA2R autoantibodies correlate well with disease activity and progression. The presence of anti-PLA2R antibodies could also potentially be used to differentiate pMN from other causes of nephrotic syndrome if a biopsy is not possible. Among patients with chronic kidney disease awaiting kidney transplantation, higher levels of anti-PLA2R could predict those more likely to recur after transplantation. In the remaining 30% of patients with MN who are PLA2R-negative, anti-thrombospondin type-1 domain-containing 7A (THSD7A) was shown to have an approximate 10% prevalence (ie, about 3% of all primary MN patients). Additionally, THSD7A has been described as a potential tumor antigen and, thus, it has been suggested that THSD7A-positive patients merit a thorough cancer screening.

Clinical Limitation

This test should not be used as a stand-alone test but an adjunct to other clinical information. A diagnosis of primary membranous nephropathy (pMN) or secondary membranous nephropathy (sMN) should not be made on a single test result. The clinical symptoms, results on physical examination, and laboratory tests (eg, serological tests), when appropriate, should always be taken into account when considering the diagnosis of pMN vs sMN. Absence of circulating anti-phospholipase A2 receptor autoantibodies does not rule out a diagnosis of pMN.