This spectrophotometry test for methaemalbumin (which has a distinctive absorption band at 558nm) should be measured in patients with suspected intravascular haemolysis and may be abnormal in patients with significant extravascular (generally splenic) haemolysis. It should generally be accompanied by estimation of the serum haptoglobin level, free plasma haemoglobin and urinary haemosiderin.

Sample: heparinised blood or clotted blood.

Kleihauer test

The Kleihauer test which exploits the resistance of fetal red cells to acid elution should be performed on all Rh(D) negative women who deliver a

Rh(D) positive infant. Fetal cells appear as darkly staining cells against a background of ghosts. An estimate of the required dose of anti-D can be made from the number of fetal cells in a low power field.

Sample: maternal peripheral blood EDTA.


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