sickle cell trait (carrier)
Last reviewed 01/2018
Sickle cell trait occurs in heterozygotes where approximately 40% of the haemoglobin is HbS, the rest being HbA, which interacts only weakly with HbS during the processes of gelation.
The heterozygote has little tendency to sickle except under conditions of severe hypoxia, ie when saturation is less than 40%.
A patient with sickle cell trait has no splenomegaly; growth, development and life-expectancy are normal. Patients may exhibit hyposthenuria - reduced ability to concentrate urine - due to diminished vasa recta flow, and small renal infarcts may also occur.
Sickle cell trait can be detected by exposing the red cells in vitro to a very low oxygen tension - Sickledex test - to initiate sickling, and by electrophoresis to show the relative globin components.