Congenital Erythrocytosis: a New Form Associated with an Erythropoietin‐dependent Mechanism

Three patients with probable congenital erythrocytosis were studied to determine the role of erythropoietin (ESF) in their disease. In addition, haemoglobin function was measured and ESF excretion determined in response to reduction in the haemoglobin concentration. In two cases ESF excretion was clearly elevated above normal, and in the third excretion was normal even at an elevated PCV. In all, phlebotomy of 15–20% of the blood volume led to more than doubling in ESF excretion. This occurred in the presence of normal molecular haemoglobin function. Studies of the renal vasculature were normal. These results suggest a new form of congenital erythrocytosis associated with increased ESF production which is reciprocally related to the oxygen carrying capacity of the blood, but in the absence of any demonstrable abnormality in oxygen transport. These findings suggest an inherited defect, likely residing in the renal sensor responsible for the production of ESF. This defect is possibly due to impaired recognition of available oxygen or else a decrease in oxygen supply at the subcellular level.