When Hb S has been detected using a primary screening method, it is then crucial to determine if the Hb S is homozygous, heterozygous, or is another variant. Additional procedures that may be needed include isoelectric focusing (IEF) or high performance liquid chromatography (HPLC).
Observation of RBC morphology and use of sickle cell screening may provide initial information for this diagnosis, but may also be negative in some sickle cell disorders.
Detection methods for Hemoglobin S include:
1. Solubility screening tests
2. Chromatographic methods such as High Pressure Liquid Chromatography (HPLC)
3. Electrophoretic methods including
a. Capillary electrophoresis
b. Cellulose acetate electrophoresis
c. Agar gel electrophoresis
d. Isoelectric focusing gels
4. Polymerase Chain Reaction (PCR) methods
Polymerized chain reaction (PCR) methods are being used in prenatal diagnosis of sickle cell disorders.
