Sickle cell disease (SCD) and sickle cell trait (SCT) are inherited blood disorders affecting hemoglobin, the protein in red blood cells that carries oxygen. SCD causes red blood cells to become rigid and crescent-shaped, leading to blockages and various health complications. Sickle cell testing screens for carriers of the trait and diagnoses those who have the disease. Understanding your status is a proactive step toward managing personal health and making informed decisions about family planning.
Who Should Seek Testing?
Testing for sickle cell status is recommended across a person’s lifespan. Universal newborn screening is standard practice in the United States, typically performed via a heel-prick blood test before the infant leaves the hospital. Early diagnosis allows children with SCD to begin preventative treatments, such as penicillin prophylaxis, which substantially improves long-term health outcomes.
Prenatal screening is highly recommended for all pregnant individuals or those planning a family, especially if they have a family history or are from ethnic groups with higher prevalence. If a pregnant person is identified as a carrier, the partner is offered testing to determine the potential risk to the child. This information aids in reproductive planning and preparing for the care of a potentially affected child.
Adults who were not screened at birth, such as those born before mandatory programs or those who have immigrated, should seek testing from a healthcare provider. Adults planning to have children should also be tested to understand the risk of passing on the gene. Certain at-risk groups, including college athletes, may also be screened to ensure appropriate precautions during intense physical activity.
Understanding the Types of Sickle Cell Tests
The initial step involves a simple blood draw for a rapid screening test, such as the solubility test, which detects abnormal hemoglobin S (HbS). While fast, a positive result only indicates the presence of HbS, meaning the person could have the trait or the disease. This test cannot definitively distinguish between the two conditions, requiring follow-up testing for confirmation.
Definitive diagnosis relies on specialized laboratory methods that separate and quantify the different types of hemoglobin present in the blood. The two gold standard techniques are Hemoglobin Electrophoresis and High-Performance Liquid Chromatography (HPLC). Both methods analyze the blood sample to measure the relative amounts of normal hemoglobin A (HbA), sickle hemoglobin S (HbS), fetal hemoglobin F (HbF), and other variants like hemoglobin C (HbC).
HPLC is often preferred in modern laboratories because it is automated, fast, and provides precise quantification of hemoglobin types. It separates them based on their chemical properties and retention time as they pass through a column. Electrophoresis separates hemoglobin variants based on their electrical charge as they move through a gel medium. A combination of these techniques ensures the most accurate diagnosis, particularly for complex cases.
Navigating the Logistics of Testing
Obtaining a sickle cell test typically begins with a request from a healthcare provider, such as a Primary Care Physician (PCP) or an Obstetrician-Gynecologist (OB-GYN). These providers issue a lab order, which is required for the blood draw at a commercial laboratory. Prenatal testing is often coordinated directly through an OB-GYN or a genetic counseling center.
For individuals without a regular doctor, testing may be accessible through public health clinics, community health centers, or specialized advocacy organizations that offer free or low-cost screenings. The cost for a screening test without insurance is generally low, though comprehensive diagnostic panels may cost more. Most major health insurance plans typically cover the cost of testing.
The turnaround time for results varies based on the testing facility and the type of analysis performed. Adult screening results may be available in as little as one business day. However, newborn screening results can take up to two weeks, depending on the state’s public health laboratory system. If the initial screen is positive, a definitive diagnostic test may require a few extra days for processing and confirmation.
Interpreting Your Sickle Cell Test Results
Sickle cell test results are reported by identifying the specific types of hemoglobin found in the blood. A result of AA indicates a person has two copies of the normal hemoglobin gene and does not have the trait or the disease. Individuals with the AS genotype have inherited one normal and one sickle hemoglobin gene, meaning they have Sickle Cell Trait (SCT).
A person with SCT is a carrier who is usually asymptomatic and does not develop SCD, but they can pass the sickle gene to their children. If both parents have the AS genotype, their child has a 25% chance of inheriting SCD with each pregnancy. Test results like SS indicate a person has inherited two sickle hemoglobin genes, resulting in the most common and severe form of Sickle Cell Disease, known as Sickle Cell Anemia.
Other common disease genotypes include SC, where a person inherits one HbS gene and one HbC gene, leading to Sickle Hemoglobin C Disease. A diagnosis of SS or SC requires immediate consultation with a hematologist to establish a comprehensive care and treatment plan. For carriers (AS), genetic counseling is the recommended next step to understand the reproductive risks and options for family planning.