Niveles de anticuerpos antirreceptor de fosfolipasa A2 en pacientes con nefropatía membranosa y síndrome nefrótico

espanolIntroduccion: La nefropatia membranosa primaria es uno de los fenotipos histologicos e inmunohistoquimicos mas frecuentes en los pacientes adultos con sindrome nefrotico. Con la identificacion del anticuerpo del receptor tipo M de la fosfolipasa A2 (PLA2R), la deteccion del Anti-PLA2 en suero cambio el enfoque diagnostico, el control de la eficacia terapeutica y el seguimiento evolutivo de esta nefropatia. En la mayoria de las series alrededor de un 70% de los pacientes virgenes de tratamiento con nefropatia membranosa en actividad son positivos para este anticuerpo. Objetivo: Nuestro objetivo fue determinar el nivel de anticuerpo en los pacientes con nefropatia membranosa y en los pacientes con sindrome nefrotico. Material y metodos: Estudio retrospectivo y observacional en donde se evaluaron 101 pacientes (86 nefropatias membranosas confirmadas por biopsia renal y 15 sin diagnostico anatomopatologico) a quienes se les realizo medicion de Anti-PLA2R. Analizamos datos demograficos, de laboratorio (creatinina, albumina, proteinuria), histopatologia renal y tratamientos instaurados. Dividimos a los pacientes con nefropatia membranosa confirmada por biopsia de acuerdo al resultado del Anti-PLA2 en 2 grupos: Positivos a los que presentaban un valor igual o > a 20 U/ml y los negativos (n=56) igual o EnglishIntroduction: Primary membranous nephropathy is one of the most frequent histological and immunohistochemical phenotypes in adult patients with nephrotic syndrome. With the identification of the M-type phospholipase A2 receptor (PLA2R), detection of serum anti-PLA2 has changed the diagnostic approach, the control of therapeutic efficacy and the evolution follow-up of this nephropathy. In most series, about 70% of MN treatment-naive patients test positive for this antibody. Objective: Our aim is to ascertain antibody level in MN patients and in nephrotic syndrome patients. Methods: In this retrospective observational study, 101 patients were evaluated (86 cases of MN diagnosed by renal biopsy and 15 with no pathologic diagnosis). They underwent the anti-PLA2R test. Demographic data, lab results (creatinine, albumin, proteinuria), renal histopathology and treatments administered were analyzed. We split MN patients diagnosed by renal biopsy into two groups according to anti-PLA2R results: Positive (those having values ≥ 20 U/mL) and Negative ([n=56] values ≤ 14 U/mL). Patients with equivocal results were not included. Results: From the total number of PMN patients diagnosed by renal biopsy, 29% (n=25) were positive for anti-PLA2R; 5.8% (n=5) had equivocal results, and 65.2% (n=56) were negative. Only 1 of the 15 patients suffering from nephrotic syndrome with no pathologic diagnosis was positive for anti-PLA2R. Anti-PLA2R testing results were positive for 47.7% of patients in a subgroup (n=35) that underwent the test no more than months after renal biopsy. No significant differences were found between the anti-PLA2R positive (n=25) and negative (n=56) groups regarding age, sex, albumin level, plasmatic creatinine and proteinuria. Conclusions: In our sample we obtained a low percentage of anti-PLA2R positivity compared to what was reported in the literature. Anti-PLA2R testing should be performed at the beginning of a nephrotic syndrome, prior to any treatment so as to determine the need of a renal biopsy, or with the result of a renal biopsy to determine if it is a primary or secondary form and evaluate the response to drugs or to “active surveillance