Sickle cell tests are used to help diagnose sickle cell anemia (also called sickle cell disease) and to identify those who may have sickle cell trait. Sickle cell anemia is an inherited disorder that leads to the production of an abnormal hemoglobin called hemoglobin S (Hb S or Hgb S). Sickle cell tests determine the presence and relative amount of hemoglobin S in a blood sample.