Thalassaemia screen

Last updated: Saturday, 01, May, 2004
Item Process
Specimen

5 mL blood in EDTA.

Method

See Haemoglobin electrophoresis
Haemoglobin A2
Haemoglobin H inclusions
unstable Haemoglobin screening.

Application

Investigation of suspected thalassaemia and other haemoglobinipathies, and screening of partners and families of affected patients.

Interpretation

The hallmark of beta thalassaemia trait is an elevated haemoglobin A2 with a mild microcytic anaemia.

Iron deficiency may, uncommonly, lead to a false negative haemoglobin A2, so that a negative screen should be repeated after iron deficiency is corrected.

Alpha thalassaemias are diagnosed by the presence of haemoglobin H bodies (tetramers of beta globin). This test may miss single alpha globin gene deletions (heterozygous a+ thalassaemias, aa/-a, see Thalassaemia (clinical problems). 

Haemoglobin S, C, E and the other variants are detected on haemoglobin electrophoresis.

Haemoglobin F is typically significantly elevated in patients with dß-thalassaemia – consult pathologist.

Reference

Chanarin I. ed. Laboratory Haematology. Churchill Livingstone 1989.

Hartman RC and Jenkins DE. N Eng J Med 1995; 275: 155-157.