Last updated: Thursday, 11, November, 2010
The following investigations are generally considered to constitute a haemolysis screen:
FBC and film, reticulocyte count, Direct and indirect antibody test (Direct and indirect Coombs), lactate dehydrogenase, haptoglobin. A urinary haemosiderin and Haemoglobin - urine, should be performed when intravascular haemolysis is considered as a differential diagnosis.
Thermal characteristics of the antibody in the direct antiglobulin test will indicate 'warm' or 'cold' antibody-mediated haemolysis.
Bone marrow aspiration and trephine biopsy, if underlying malignancy (especially lymphoproliferative disorder) is suspected. Compatibility testing may be difficult in patients with autoimmune haemolysis, so blood group with an extended red cell phenotype and antibody screen should be requested at the time of the diagnosis; consult pathologist.
|'Warm' antibody haemolysis|
Direct antiglobulin test detects IgG antibodies bound to red cells, with or without complement.
Lymphoproliferative disorders, especially
Haemolytic amaemia may precede the diagnosis of a lymphoproliferative disorder.
Ensure that the drug history is included on the laboratory request form. Indirect antiglobulin test, with in vitro addition of drug, if appropriate.
Autoimmune - type haemolysis.
Cephalosporins, tetracycline, tolbutamide and semi synthetic penicillins are in this group that cause drug-hapten induced haemolysis.
'Cold' antibody haemolysis
Usually due to IgM antibodies; direct antiglobulin test usually detects complement only bound to red cells. Cold agglutinins.
Antibody has anti-I specificity.
Antibody has anti-i specificity.
Paroxysmal cold haemoglobinuria