Serum erythropoietin levels in patients with congenital heart disease.

Serum erythropoietin levels were measured by radioimmunoassay in 146 children and young adults with congenital heart disease to assess the relationship between erythropoietin and clinical factors (heart failure, anemia, cyanosis) and hemodynamic variables affecting oxygen delivery and utilization. Erythropoietin values were in the normal range (10 to 30 microU/mL) in 73% (58 of 80) of the patients with and 82% (54 of 66) of those without cyanosis. Elevated erythropoietin values in cyanotic patients were associated with lower mixed venous oxygen saturation and tension than in cyanotic patients with normal erythropoietin levels, even though the degree of polycythemia was similar. In contrast, most of the acyanotic patients who had elevated erythropoietin levels were anemic. Of the blood oxygen measurements, mixed venous oxygen saturation and tension had the closest inverse correlation with erythropoietin values. The normal erythropoietin values in most patients are in accord with other observations that show that an elevation in erythropoietin level in response to hypoxia will be transient if it results in a rise in hemoglobin concentration "appropriate" to the degree of hypoxia. Persistent elevation of erythropoietin in patients with congenital heart disease may indicate harmful impairment of hemoglobin production that is potentially correctable.