Polycythaemia caused by increased erythropoietin secretion occurs in association with renal cell carcinoma, cerebellar haemangioblastomas and, less commonly, with adrenal, ovarian and hepatic neoplasms.
Since erythropoietin is normally produced by the kidney, the syndrome that develops in patients with renal cell carcinoma does not fit into the category of the ectopic humoral syndrome. At present, the assay for plasma erythropoietin levels is not sufficiently reliable, making the differential diagnosis between ectopic erythropoietin syndrome and other mechanisms that generate erythrocytosis in cancer patients sometimes difficult; the latter mechanisms include the production of substances with erythropoietic activities or activities to stimulate erythropoietin production, such as androgenic hormones, prostaglandins, and b-adrenergic antagonists. Erythrocytosis usually does not require treatment.
