Haemoglobin S

Keywords: HbS

Specimen:

5 mL blood in any anticoagulant.

Method:
  1. Examination of blood film incubated with reducing agent.

  2. Qualitative solubility test in presence of reducing agent.

  3. Haemoglobin electrophoresis and HPLC.

Application:

Investigation where Sickle cell disease (SS) or trait (AS) is suspected. See Sickle cell disorders.

HbS may be present with other abnormalities (eg, HbS/thalassaemia).

Women from ethnic backgrounds where sickle cell disease is common should be screened prior to, or early in pregnancy, in combination with partner screening as indicated. This is to identify couples who are at risk of having a child with sickle cell disease so that prenatal testing and counselling can be offered.

Preoperative screening for sickle cell disease should also be carried out in patients from ethnic backgrounds with a high prevalence of sickle cell disease.

At risk ethnic groups include individuals derived from Mediterranean, Arabic, Middle Eastern and West African regions.

Specific HbS testing is required since individuals with sickle cell trait may not have any abnormalities on the full blood count, which cannot be relied on as a screening test.

See Haemoglobinopathy.

Interpretation:

Sickle cell tests depend on decreased solubility of HbS at low oxygen tensions or on characteristic mobility of HbS on electrophoresis.

Reference:

Working Party of the General Haematology Task Force of the British Committee for Standards in Haematology. Br J Haematol 1998; 101: 783-792.

Ryan K et al. Significant haemoglobinopathies: guidelines for screening and diagnosis. BJH 2010: 149(1) 35-49