Sickle Cell Screen Test

The sickle cell screen—sometimes called the sickle solubility test—is an initial check to see if your red blood cells contain any hemoglobin that tends to “sickle.” These sickling hemoglobins cause red blood cells to become stiff and crescent-shaped under stress, like during low oxygen, dehydration, or illness. When this happens, the cells can clog blood vessels, trigger pain episodes, and shorten red cell lifespan, leading to anemia. This is the core issue in sickle cell disease.

The test works by mixing your blood with a solution that causes abnormal hemoglobins (like hemoglobin S, and others like C-Harlem or D-Punjab) to clump together and turn the solution cloudy. If the test is positive, it suggests the presence of a sickling hemoglobin—but it doesn’t tell you which one, or whether you carry one sickling gene (called sickle cell trait) or two (which causes sickle cell disease).

That’s important, because people with sickle cell trait (who carry just one copy of the gene) are usually healthy but can pass the trait to their children. Those with two sickling genes—like SS, SC, or S-beta thalassemia—have a more serious condition that can lead to lifelong complications. Some people carry combinations that include other hemoglobin mutations that still cause sickling but behave differently from classic sickle cell anemia.

This is why a positive result on this screen is just the start. It must be followed by more precise testing—like hemoglobin electrophoresis or high-performance liquid chromatography (HPLC)—to identify the exact type of hemoglobin present and what that means for your health.