Erythrocytosis associated with diffuse parenchymal lesions of the kidney.

Thirteen patients with diffuse parenchymal disease of the kidney and erythrocytosis are reported. In five the haematocrit was only minimally elevated because of an associated increase in plasma volume. The erythrocytosis in three patients was of particular interest: (1) transient appearance in a 23-year-old man with glomerulonephritis; (2) persistence despite the partial remission of nephrotic state in a 19-year-old man; (3) appearance following removal of a nephrosclerotic kidney from a 54-year-old woman. Because an associated expansion of plasma volume is not uncommon with parenchymal renal disease, it is suggested that the only reliable screening method for renal erythrocytosis is direct measurement of red cell volume.