Secondary polycythemia associated with membranous nephropathy.

A 61-year-old male patient had secondary polycythemia associated with idiopathic nephrotic syndrome. Renal biopsy revealed membranous nephropathy. Polycythemia did not change in spite of partial remission of proteinuria. Serum erythropoietin determined by an enzyme-linked immunosorbent assay was 7.2 mU/ml. His serum erythropoietin maintained at a constant level during polycythemia was higher than it was before the appearance of renal ischemia, so he was kept in a polycythemic state. Whether decreasing proteinuria can improve renal ischemia requires future study. We must observe the patient for the occurrence of thromboembolism. Renal ischemia possibly induced by nephrotic syndrome is likely to cause secondary polycythemia.