Idiopathic Membranous Glomerulonephritis Leading to Secondary Polycythemia: A Rare Association.

Primary polycythemia is caused due to mutations in erythropoietin (EPO) receptor or Janus Kinase 2 (JAK2). Secondary polycythemia is seldom associated with renal diseases, such as adult polycystic kidney disease, kidney tumors (like renal cell carcinoma and reninoma), renal artery stenosis, and kidney transplant due to increased EPO production. Polycythemia associated with nephrotic syndrome (NS) is very rare. Here, we report a case with membranous nephropathy, the patient had polycythemia at presentation. Nephrotic range proteinuria causes nephrosarca leading to renal hypoxia which causes increased EPO and IL-8 production, this is proposed to cause secondary polycythemia in NS. The reduction of polycythemia following remission in proteinuria further suggests the correlation. The exact mechanism remains to be found out.