Increased erythropoietin synthesis in patients with COLD or left heart failure is related to alterations in renal haemodynamics

Background The mechanisms controlling erythropoietin (EPO) synthesis by the kidney in patients with chronic obstructive lung disease (COLD) or congest ive left heart failure (CLHF) remain incompletely understood. Renal dysfunc tion occurs as a consequence of decreased renal blood flow (RBF) in these d iseases. Because alterations in renal haemodynamics may affect EPO synthesi s and red blood cell production, we investigated the potential relationship s between renal function and plasma EPO synthesis in patients with COLD or CLHF. Materials and methods Thirty-two patients with COLD and 13 with CLHF underw ent determination of renal physiology parameters, plasma EPO levels and hae moglobin levels. Results Plasma EPO concentrations were increased in patients with COLD or C LHF as compared to normal subjects, and were inversely correlated to haemog lobin concentrations. In patients with COLD or CLHF, plasma EPO was negativ ely correlated with both RBF and renal oxygen delivery (ROD) and positively correlated with filtration fraction. Plasma EPO was not correlated with gl omerular filtration rate, fractional excretion of sodium, PO2 or PCO2. Amon g the patients with COLD, those with polycythemia (haemoglobin > 150 g L-1) had lower plasma EPO and higher RBF and ROD values than those with normocy themia (haemoglobin less than or equal to 150 g L-1). Conclusions Taken together, our data suggest that in patients with COLD or CLHF the critical determinant for EPO production is impairment of renal hae modynamics.