Sickle Cell Disease: Symptoms, Diagnosis, and Treatment

Definition

Sickle cell disease (SCD) is a condition that causes red blood cells to lose their round shape and take on a crescent or “sickle” shape. This happens because the hemoglobin protein in the red blood cells is abnormal. This makes the hemoglobin hard and sticky. And this changes the shape of the red blood cell and makes it hard for blood to flow normally.

Abnormally shaped red blood cells can clump together and get stuck as they try to move through the blood vessels and deliver oxygen to the body. As a result, some tissues and organs in the body won’t get the blood or oxygen they need to function. This can lead to painful “sickle cell crisis” episodes and different medical complications. These abnormal red blood cells are very fragile and easily destroyed, which can lead to anemia (low red blood cell count).

SCD is present at birth and is the most common genetic blood disorder. Up to 100,000 people have SCD in the U.S. And Black people are particularly affected by this condition. About 1 in 365 Black babies are born with SCD.

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Causes

SCD is an inherited condition. This means parents pass it to their children. SCD happens when you get two abnormal hemoglobin genes — one from each parent. When you get one normal and one abnormal hemoglobin gene from your parents, you become a carrier of sickle cell trait. Most people with sickle cell trait have no symptoms of SCD.

The likelihood of having SCD or sickle cell trait depends on how many abnormal genes each parent has. If both parents have sickle cell trait (one abnormal hemoglobin gene), each child has a 25% chance of being born with SCD. There’s also a 50% chance of each child being born with sickle cell trait.

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Risk factors

Certain risk factors make it more likely for you to have sickle cell disease. Those more likely to have the genetic mutation for SCD include people who are of:

• African descent 

• Hispanic heritage from Central and South America

• Middle Eastern descent

• Indian descent

• Asian descent

• Mediterranean descent

Types of SCD

There are many different types of SCD. The type of SCD you have will depend on which hemoglobin genes you inherit and how this affects your red blood cells. Common forms of SCD include:

• HbSS: This is the most severe form. Both parents have an abnormal hemoglobin S gene. It’s often called sickle cell anemia.

• HbSC: This is a milder form of SCD. One parent has an abnormal hemoglobin S gene and the other has an abnormal hemoglobin C gene.

• HbS beta thalassemia: One parent also has a gene for thalassemia, which can lead to either a severe or mild form of SCD.

Symptoms

Symptoms of SCD can differ from person to person. And they can also vary over time as more complications arise. Sometimes, people with SCD can go long periods of time without any symptoms at all. 

With SCD, it’s common to have episodes of: 

• Pain (sickle cell crisis)

• Jaundice (yellowing of the skin or eyes)

• Fatigue

• Swelling in the hands or feet

• Dizziness

• Shortness of breath

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Complications

There are also many complications that can develop as a result of SCD. These include:

• Anemia (low red blood cell count)

• Stroke

• Priapism (painful, prolonged erection)

• Acute chest syndrome (severe lung damage)

• Pulmonary hypertension

• Infection

• Organ damage (such as to the heart, kidney, liver, or spleen)

• Vision loss

• Avascular necrosis (bone damage due to lack of blood flow)

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Diagnosis

SCD is diagnosed using a blood test. 

Basic blood tests, called hemoglobin electrophoresis, will tell you if you have abnormal hemoglobin circulating in your blood. 

Genetic blood tests can outline what type of SCD you have and which abnormal genes you carry. This can also be used to see if you carry the sickle cell trait, which you could pass to any future children. 

Your primary care provider may suggest testing for the sickle cell genes if:

• You have symptoms of SCD

• You’re pregnant (to test the unborn child for SCD)

• You have a newborn (to test the newborn for SCD or sickle cell trait)

In some U.S. states, all newborns are tested for the sickle cell gene as part of their newborn screening.

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Medications

Medications won’t cure SCD, but they can make living with the condition easier. There are several medications to help manage the symptoms and complications of SCD.

Commonly used medications include:

• Crizanlizumab (Adakveo): This medication helps to prevent red blood cells from clumping together in the blood vessels, decreasing the number of pain crises. 

• Hydroxyurea (Hydrea): This medication works to prevent complications of SCD like acute chest syndrome, anemia, and hospitalizations.

• L-glutamine (Endari): This medication helps to decrease the number of pain crises from SCD.

• Penicillin: This antibiotic helps to prevent infections. For some people with SCD, it may be a lifelong, daily medication.

Pain medications are often used during a sickle cell crisis. They include over-the-counter pain relievers, like acetaminophen or ibuprofen. Other options are prescription pain medications (like opioids) that are given in a hospital or clinic setting.

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Treatments

There are many treatments that can help extend the life of people with SCD. These treatments can even bring a cure in some cases. They can include blood and bone marrow transplant, transfusions, and genetic therapies. 

Let’s take a closer look at each of these treatment options.

Blood and bone marrow transplant

A blood and bone marrow transplant can cure SCD in some cases. Data shows it to be effective in up to 95% of children who had a donor that was a close relative and genetic match. 

But it’s a dangerous procedure with a high risk of complications. That’s why it’s almost always performed in children who have had serious SCD complications. Also, children are more likely to tolerate the procedure than adults. 

Blood transfusion

Blood transfusion is a common treatment to prevent complications of anemia in SCD. A transfusion supplies normal red blood cells that function and last longer than sickled red blood cells. This improves blood flow. And that makes it useful in preventing and treating complications like stroke or as preparation before surgery.

Genetic therapies

Researchers continue to explore genetic treatments as a way to repair the gene mutations for abnormal hemoglobin. There are now two FDA-approved genetic treatments for SCD: Casgevy and Lyfgenia. 

These treatments work by taking stem cells from a person with SCD. The cells are genetically altered so they’re no longer affected by an abnormal hemoglobin gene. The cells are then injected back into the same person’s bone marrow, where they can begin to make normal red blood cells. 

Early data is promising that these treatments could be another method of curing SCD. Clinical trials are ongoing to evaluate the long-term effects of these treatments for people living with SCD.

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Living

Living with sickle cell disease requires a lifelong commitment to a healthy lifestyle. This will help to prevent complications and reduce sickle cell crises. 

Here are some ways you can improve your health with SCD:

• Have regular checkups with a healthcare professional.

• Stay hydrated.

• Eat a well-balanced diet.

• Avoid infections.

• Rest well.

• Avoid extreme temperatures.

Another tool to help you on your SCD journey is to find and participate in clinical trials. This allows you to be a part of cutting edge research and therapies that are getting closer to a cure each day.

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