HAPTOGLOBIN - plasma or serum

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Specimen: 5 mL blood in anticoagulated or plain tube.

Method: Immunoassay. Electrophoresis and column chromatography rarely performed.

Reference Interval: 0.3-2.0 g/L.

Application: Rarely required in the investigation of possible intra- or extra-vascular haemolysis. Value limited by low sensitivity and specificity. May be used as a measure of ongoing haemolysis in TTP during plasma exchange therapy.

Interpretation: Haptoglobin binding of free haemoglobin results in removal of the complex from the circulation. Reduced levels occur in haemolysis (particularly intravascular), megaloblastic anaemia (red cell turnover in marrow) following blood transfusion, massive tissue haemorrhage, and hepatocellular disease. Congenital absence of haptoglobin has also been recognised. High levels may be seen in pregnancy, with steroid or oestrogen therapy, in conditions associated with an acute phase response, and in biliary obstruction. Pre-existent high levels may mask haemolysis.

Reference: Owen JA et al. J Clin Pathol 1969; 13: 163-164.

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