Studies on the Mechanism of Erythrocytosis Associated with a Uterine Fibromyoma

Abstract

S ummary . Erythrocytosis has occasionally been associated with uterine fibromyoma and attributed to an inappropriate elaboration of erythropoietin (Ep) by the tumour. Whether Ep per se , its precursor substrate, or activator analagous to the renal erythropoietic factor (REF) is produced, has not been defined. In a 54‐yr‐old woman with erythrocytosis and uterine fibromyoma, plasma, urine and tumour extracts were examined to clarify these possible mechanisms. Preoperatively, elevated serum and urinary Ep were present with constant levels over a range of haematocrits induced by serial phlebotomy. Extracts of the tumour did not generate Ep when incubated with normal serum, nor did they contain substrate activity for known REP. Tumour extracts did, however, possess Ep activity which was abolished with anti‐Ep. The patient has remained haematologically normal more than 1 yr following surgery. The data show that the erythrocytosis associated with uterine fibromyoma is mediated through the direct production of Ep by the tumour and not by a substrate‐REF‐like mechanism as found in the normal kidney.