Sickle cell disease – Diagnostics – Overview of Information and Clinical Research

Finding out whether someone has sickle cell disease is a crucial step in preventing complications and managing this inherited blood disorder effectively. Early diagnosis allows healthcare teams to start protective measures and personalized care plans that can help people with the condition live fuller, healthier lives.

Introduction: Who Should Undergo Diagnostics

Diagnosing sickle cell disease early is one of the most important steps in protecting health and preventing serious complications. In the United States, every newborn is now screened for sickle cell disease as part of routine newborn screening programs. This means that most people who have the condition learn about it within the first few days of life, usually before symptoms even begin.^[1]^[2]

However, not everyone with sickle cell disease is diagnosed at birth, especially if they were born in countries where newborn screening is not available or if they were born before these programs became widespread. Adults and older children who experience unexplained symptoms such as repeated episodes of severe pain, frequent infections, yellowish eyes or skin, extreme tiredness, or swelling in the hands and feet should seek medical evaluation. These signs could point to sickle cell disease or other blood disorders that require attention.^[3]

Pregnant women and couples who are planning to have children may also benefit from diagnostic testing, especially if they have a family history of sickle cell disease or come from regions where the condition is more common. People with African, Caribbean, Mediterranean, Middle Eastern, or Indian ancestry are at higher risk of carrying the gene that causes sickle cell disease. If both parents carry the gene, their children could inherit the disease.^[2]^[4]

Anyone who has a family member with sickle cell disease should also consider getting tested. Knowing whether you carry the sickle cell trait is important not only for your own health but also for understanding the risks when planning a family. Carriers of the trait usually do not have symptoms, but they can pass the gene to their children.^[5]

⚠️ Important

If you experience a high fever above 38°C, severe pain that does not respond to home treatment, breathing difficulties, sudden weakness, or confusion, seek medical care immediately. These could be signs of serious complications related to sickle cell disease that need urgent attention.

Diagnostic Methods

The main way to diagnose sickle cell disease is through a blood test. This test looks for the abnormal type of hemoglobin, which is the protein inside red blood cells that carries oxygen throughout the body. In people with sickle cell disease, this hemoglobin is different from the normal version and is called hemoglobin S. The test can identify not only whether someone has the disease but also what type of sickle cell disease they have.^[11]^[7]

The blood sample for this test is usually taken from a vein in the arm for adults and older children. For newborns and very young babies, the sample is often collected from a heel prick. This small amount of blood is then sent to a laboratory where it is screened for abnormal hemoglobin. The results can tell doctors whether a person has hemoglobin S and whether they have inherited one or two copies of the abnormal gene.^[11]

There are different types of sickle cell disease, depending on which genes a person inherits from their parents. The most common and severe form is called sickle cell anemia or hemoglobin SS disease. This happens when someone inherits two copies of the hemoglobin S gene, one from each parent. Other forms include hemoglobin SC disease, where one parent passes on hemoglobin S and the other passes on a different abnormal hemoglobin called hemoglobin C. There is also a form called sickle cell beta thalassemia, which involves hemoglobin S and a beta thalassemia gene. Blood tests can distinguish between these different types, which is important because the severity of symptoms and complications can vary.^[2]^[6]

In pregnant women who want to know whether their unborn baby has sickle cell disease, testing can be done before birth. This is called prenatal testing. Two main procedures are used: amniocentesis and chorionic villus sampling. Amniocentesis involves taking a small sample of the fluid that surrounds the baby in the womb, while chorionic villus sampling takes a tiny piece of tissue from the placenta. Both procedures can detect whether the baby has inherited the genes for sickle cell disease. These tests are offered to parents who are known carriers of the sickle cell gene or who have a family history of the condition.^[9]^[11]

In addition to the initial blood test that confirms the diagnosis, doctors often recommend other tests to understand how the disease is affecting the body. Baseline blood studies help measure the level of anemia, which is common in sickle cell disease because the sickled cells die faster than normal red blood cells. Doctors may also check for signs of organ damage, infections, or other complications. These tests can include urine tests to check kidney function, imaging tests to look at the lungs, heart, or brain, and tests to measure oxygen levels in the blood.^[15]^[7]

A special type of ultrasound called transcranial Doppler ultrasonography is used in children with sickle cell disease to assess their risk of stroke. This painless test uses sound waves to measure how fast blood is flowing through the vessels in the brain. If the blood flow is too fast, it can mean that the blood vessels are narrowing, which increases the risk of stroke. This test is often done regularly in children starting around the age of two to catch any problems early.^[11]^[15]

Screening for sickle cell disease is routine in many countries. In the United Kingdom, all pregnant women are offered screening to check if there is a risk of their child being born with the condition. In the United States, newborn screening for sickle cell disease is mandatory in all states. This means that most babies are tested within the first few days of life as part of the heel prick test, which screens for many different conditions. Early detection through newborn screening allows doctors to start preventive treatments, such as antibiotics and vaccines, before symptoms appear.^[5]^[2]

Diagnostics for Clinical Trial Qualification

When people with sickle cell disease are being considered for participation in clinical trials, additional diagnostic tests are often required. Clinical trials are research studies that test new treatments or therapies to see if they are safe and effective. To make sure that the right patients are enrolled and that the trial results are accurate, researchers use specific tests to confirm the diagnosis and assess the severity of the disease.^[10]

The first step in qualifying for a clinical trial is usually a blood test to confirm that the person has sickle cell disease and to identify which type they have. This is done through the same hemoglobin testing used in standard diagnosis. Researchers often need to know whether participants have hemoglobin SS, hemoglobin SC, or another variant because the response to treatment can differ depending on the type of disease.^[14]

Clinical trials may also require baseline laboratory evaluations to measure how well the body’s organs are functioning. These can include tests of the liver, kidneys, heart, and lungs. For example, blood tests might check liver enzymes, kidney function markers, and blood cell counts. Imaging tests such as chest X-rays, ultrasounds, or magnetic resonance imaging (MRI) scans might be used to look for signs of organ damage or complications like strokes or lung problems.^[15]

Pain is one of the most common symptoms of sickle cell disease, and many clinical trials focus on treatments that reduce the frequency or severity of pain crises. To qualify for these trials, participants may need to document how often they experience pain episodes, how severe the pain is, and how much it affects their daily life. Doctors may ask patients to keep a pain diary or complete questionnaires that measure pain and quality of life.^[10]

Some clinical trials test gene therapies or stem cell transplants, which are advanced treatments that aim to cure sickle cell disease. For these trials, additional genetic testing may be required to analyze the patient’s DNA and confirm the specific mutation that causes the disease. Doctors may also conduct tests to evaluate the patient’s overall health and to check whether they have complications that might affect the success of the treatment or increase the risks.^[10]^[14]

Blood transfusion history is another important factor in clinical trial qualification. Some treatments require that participants have not received blood transfusions recently, while others may specifically enroll people who need regular transfusions. Doctors will review medical records to understand the patient’s transfusion needs and history of complications.^[15]

⚠️ Important

If you are interested in participating in a clinical trial for sickle cell disease, speak with your healthcare provider or sickle cell specialist. They can help you understand which trials you might be eligible for and what diagnostic tests will be needed. Clinical trials offer access to new therapies that may not yet be available to the general public.

In clinical trials for newer medications such as hydroxyurea, L-glutamine, or crizanlizumab, researchers may require regular blood tests to monitor how the treatment is affecting the body. These tests check for side effects and measure whether the medication is reducing the frequency of pain crises or improving other symptoms. Participants may need to visit the clinic or hospital regularly for blood draws and physical examinations.^[12]^[10]

For trials involving stem cell or bone marrow transplants, finding a suitable donor is a critical part of the process. Doctors use blood tests to match the patient’s tissue type with potential donors, often family members. The closer the match, the better the chances of a successful transplant. Genetic testing and immune system tests are used to identify the best donor and to reduce the risk of complications such as graft-versus-host disease, where the transplanted cells attack the patient’s body.^[13]^[14]

Clinical trials are carefully designed to protect participants and to ensure that the data collected is reliable. Diagnostic tests are used not only to qualify patients for enrollment but also to monitor their progress throughout the trial. This helps researchers understand whether the treatment is working and whether it is safe. People with sickle cell disease who participate in clinical trials play an important role in advancing medical knowledge and improving care for future patients.^[4]

Prognosis and Survival Rate

Prognosis

The outlook for people with sickle cell disease has improved significantly over the past few decades, thanks to early diagnosis, better treatments, and comprehensive care programs. The severity of sickle cell disease varies widely from person to person. Some people experience mild symptoms and lead relatively normal lives with few complications, while others face frequent pain crises, organ damage, and serious health challenges. The type of sickle cell disease a person has plays a role in their prognosis. For example, hemoglobin SS disease, also known as sickle cell anemia, is usually the most severe form, while hemoglobin SC disease and some types of sickle beta thalassemia may cause milder symptoms.^[2]^[6]

Complications from sickle cell disease can affect many parts of the body, including the brain, lungs, kidneys, heart, liver, bones, and eyes. Serious complications such as stroke, acute chest syndrome, infections, and organ damage can shorten life expectancy if not managed properly. However, with good medical care, including regular check-ups, preventive medications, vaccinations, and prompt treatment of complications, many people with sickle cell disease live into their 50s and beyond. Some newer treatments, including gene therapies, offer the potential for even better outcomes and longer, healthier lives.^[1]^[5]^[16]

Factors that can improve prognosis include early diagnosis through newborn screening, access to comprehensive sickle cell care programs, adherence to treatment plans, avoiding triggers that cause crises, and maintaining a healthy lifestyle. Regular use of medications such as hydroxyurea and preventive antibiotics can reduce the frequency of pain crises and infections. Staying up to date with vaccinations and seeking prompt medical care for fevers or other warning signs are also critical for preventing life-threatening complications.^[17]^[13]

Survival rate

In the past, many children born with sickle cell disease did not survive into adulthood. However, advances in medical care have dramatically improved survival rates. Today, with appropriate care and early intervention, about half of people with sickle cell anemia live into their 50s. Some individuals with milder forms of the disease may live even longer.^[16]^[5]

In 2021, sickle cell disease was responsible for approximately 81,100 deaths in children under five years old worldwide, making it the 12th leading cause of death in this age group. However, these numbers do not capture the full impact of the disease, as many deaths related to complications of sickle cell disease are recorded under other causes. When considering the total mortality burden, actual deaths associated with sickle cell disease are estimated to be much higher—around 376,000 deaths per year globally, compared to only 34,400 deaths officially recorded as directly caused by the disease.^[8]

The life expectancy for people with sickle cell disease is generally shorter than that of the general population, but this varies depending on the type of disease, access to medical care, and how well complications are managed. People with sickle cell anemia tend to have shorter life expectancies than those with other forms of sickle cell disease. However, the availability of new therapies, including gene therapies and improved supportive care, is expected to continue improving survival rates in the coming years.^[9]^[6]

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