Sickle cell disease is a genetic blood disorder affecting red blood cells, which are typically round and flexible. In this condition, red blood cells can become stiff, sticky, and C-shaped, resembling a sickle. These abnormally shaped cells can block blood flow, leading to pain and other serious health problems. Testing for sickle cell status is important for managing the condition or making informed family planning decisions.
The Primary Test for Sickle Cell
The most common and definitive blood test for identifying sickle cell disease and sickle cell trait is Hemoglobin Electrophoresis. This method separates different types of hemoglobin, the oxygen-carrying protein in red blood cells, based on their electrical charge. It detects the presence and amounts of normal hemoglobin (HbA) and abnormal hemoglobins like HbS, characteristic of sickle cell conditions.
While initial screening tests like the Sickle Solubility Test can indicate the presence of HbS, they cannot differentiate between sickle cell trait and sickle cell disease. If a screening test yields a positive result, a confirmatory test like Hemoglobin Electrophoresis is necessary for a precise diagnosis.
Why and How Testing is Performed
Testing for sickle cell conditions serves several purposes, including universal newborn screening, diagnostic testing for individuals experiencing symptoms, and carrier screening for family planning. All newborns in the United States undergo screening for sickle cell anemia shortly after birth, typically within 48 hours. This early detection allows for prompt medical intervention, which can significantly improve health outcomes for affected infants.
For diagnostic purposes, testing may be recommended for individuals with symptoms like unexplained anemia or severe pain. Carrier screening is also offered to pregnant individuals or those considering pregnancy, especially with a family history or ethnic background associated with higher prevalence. The procedure involves a blood sample, typically drawn from a vein in the arm or a heel prick for newborns, which is then sent for laboratory analysis.
Interpreting Your Results
Interpreting sickle cell test results involves identifying the specific types and quantities of hemoglobin present in the blood. A “normal” result indicates the absence of sickle hemoglobin, meaning the individual has primarily normal adult hemoglobin (HbA), suggesting no sickle cell disease or trait.
If the test reveals both normal hemoglobin (HbA) and a smaller amount of sickle hemoglobin (HbS), typically with HbA more abundant than HbS, the individual is diagnosed with Sickle Cell Trait (SCT), often denoted as HbAS. People with SCT usually do not experience symptoms, but they carry one copy of the sickle cell gene and can pass it on to their children. A diagnosis of Sickle Cell Disease (SCD) is made when the test shows a significant amount of HbS, often with other abnormal hemoglobins like HbC (HbSC disease) or in the absence of HbA (HbSS disease). Specific types of SCD, such as HbSS, HbSC, or HbS Beta Thalassemia, are identified by the specific combination and proportion of hemoglobins. Individuals with SCD typically experience various symptoms and require ongoing medical care.
What Happens After Testing
The steps taken after receiving sickle cell test results depend on the diagnosis. Normal results provide reassurance that the individual does not have sickle cell trait or disease. For those diagnosed with Sickle Cell Trait, genetic counseling may be recommended, particularly for individuals planning to have children. This counseling helps them understand the implications of carrying the trait and passing the gene to their children.
When a diagnosis of Sickle Cell Disease is confirmed, individuals are typically referred to a hematologist, a doctor specializing in blood disorders, or a specialized care team. This referral initiates a path of ongoing medical management, which includes education about the condition, monitoring for complications, and discussing available treatment options. Early diagnosis and proactive care are important for managing sickle cell disease and improving the quality of life for affected individuals.