Haptoglobin is present in albumin used as a replacement solution for plasma exchange

BACKGROUND: Albumin is frequently used as replacement solution when performing plasma exchanges (PEs) and there are no previous data about the content of haptoglobin. The objective was to study the content of haptoglobin in albumin solution and the effect of PE on the removal of haptoglobin, a plasma protein often used for monitoring hemolytic conditions treated with PE. STUDY DESIGN AND METHODS: Haptoglobin was measured in the 5% albumin replacement solution. It was also measured before and after performing 12 PEs using 5% albumin as a replacement solution on four patients. There were three patients with haptoglobin values within the reference range before starting PEs whereas one patient had low levels because of microangiopathic hemolytic anemia. RESULTS: The mean content of haptoglobin in the 5% albumin replacement solution was 0.157±0.005g/L. Predicted removal according to the one-compartment model was 70% to 77%. Real removal (RR) of haptoglobin in patients with values within the reference range was 7% to 67%. The RR correlated with the value of haptoglobin before performing PE (r=0.709; r(2) =0.502; p=0.03). When haptoglobin levels were low before PE, the levels after the PE were those present in the albumin used as a replacement solution. CONCLUSION: Albumin solution used for PE contained haptoglobin and it explained in part the kinetics removal of plasma haptoglobin observed in the patients.