What is hydroxyurea?
Hydroxyurea is a medicine that can help children and adults with sickle cell disease.
Research studies show that hydroxyurea lowers the following:
- The numbers of acute chest syndrome (pneumonia) events
- The number of pain crises
- The need for blood transfusions
- The number of trips to the hospital
- Hydroxyurea also might prevent damage to the spleen, kidneys, lungs, and brain.
Hydroxyurea is given by mouth one (1) time each day. It comes in a capsule form. The U.S. Food and Drug Administration (FDA) has approved it for the treatment of adults and children with severe sickle cell disease. Numerous medical centers have carried out research studies to learn more about giving hydroxyurea safely and effectively to children with sickle cell disease.
Which children should take hydroxyurea?
We consider hydroxyurea for children with sickle cell disease who have had:
- Many painful events.
- Several cases of acute chest syndrome (pneumonia).
- Severe anemia
- Other special problems with their internal organs.
Children with SS and S Beta Zero variants may start on hydroxyurea prophylactically by the age of 9-12 months.
How does hydroxyurea work?
Red blood cells contain hemoglobin. Hemoglobin helps red blood cells carry oxygen from the lungs to other parts of the body. People with normal hemoglobin have mostly Hemoglobin A in their red blood cells. People with sickle cell disease have mostly sickle or Hemoglobin S (Hb S) in their red blood cells.
Hb S is an abnormal type of hemoglobin. In people with sickle cell disease, Hb S causes the red blood cells to change from a round shape to a sickle or banana shape. Also, Hb S causes the red blood cells to become rigid and sticky. This leads to blockage of blood flow to important body organs, muscles, and tissues.
Hydroxyurea treatment helps the red blood cells stay round and flexible. This lets them travel more easily through tiny blood vessels. In part, this happens because hydroxyurea increases the amount of fetal hemoglobin (Hb F) in red blood cells. Newborn babies have Hb F when they are born. Hb F helps protect them from sickle cell complications (health problems) during the first few months of life. With an increased amount of Hb F, red blood cells are less likely to change into the sickle or banana shape. In most people, the amount of Hb F decreases after the first few months of life. Some people have more Hb F than others. People with sickle cell disease who have higher levels of Hb F usually have fewer complications of the disease.
Is hydroxyurea a cure for sickle cell disease?
No. Hydroxyurea does not cure sickle cell disease. Hydroxyurea can greatly reduce majority of the complications of the disease. It does not work if it is not taken as instructed. Usually, it takes 2- 3 months before you will see results or get any benefit from the medicine. It takes that long to reach the right dose of Hydroxyurea. It is important to remember that Hydroxyurea must be taken every day for it to work well.
Is hydroxyurea safe?
Hydroxyurea was first used as a treatment for cancer. It is a powerful medicine. But hydroxyurea is given at a much lower dose to children with sickle cell disease. No serious side effects have been seen in children with sickle cell disease. The dose used in the treatment of sickle cell disease does not cause the usual side effects seen with cancer treatment. It does not cause hair loss, vomiting, weakness, or loss of appetite.
Many children with sickle cell disease have taken hydroxyurea for several years without problems. Hydroxyurea is very safe when given by medical specialists experienced in caring for patients with sickle cell disease.
In most sickle cell centers consent is no longer required.
In children with sickle cell disease it takes several months to reach the full dose of hydroxyurea. At full dose, the medicine should slightly reduce the number of blood cells in the body. One type of blood cell that can be reduced is a white blood cell called a neutrophil. Neutrophils help fight infection in the body. For this reason, frequent blood tests are needed to check the blood counts. If the white blood cells are low, the dose of hydroxyurea will be decreased.
The side effects of taking hydroxyurea for a long time are not completely known. In the past, there has been concern about a possible cancer risk while taking hydroxyurea. But, an increased risk of cancer has not been found in children and adults with sickle cell disease. Some of these patients have been treated with hydroxyurea for as long as 15 years. The risk of cancer appears to be no different for people who have sickle cell disease and are taking hydroxyurea than for those who are not taking hydroxyurea.
What tests are done to monitor hydroxyurea treatment?
Patients taking hydroxyurea usually have physical exams and have their blood counts checked for the first three months every two weeks then monthly. They will be seen more often if needed.
Is hydroxyurea the only treatment for sickle cell disease?
Hydroxyurea is not the only choice of treatment at this time. Red blood cell transfusions are another treatment choice. Transfusions have been used for many years to treat stroke and problems with the brain in people with sickle cell disease.
Another treatment choice is stem cell transplant (sometimes called bone marrow transplant). This is the only cure for sickle cell disease. Stem cell transplants replace the patient’s bone marrow with normal bone marrow. This causes the body to make mostly Hemoglobin A instead of abnormal Hb S. But transplants require a matched donor and can sometimes cause severe side effects, including occasional severe illness or death.
Gene therapy is the treatment of the near future with aim to cure patients in a less aggressive way that bone marrow transplant.
How do I get more details about hydroxyurea?
The Division of Hematology/Oncology at Nicklaus Children’s Hospital has been caring for children with sickle cell disease using hydroxyurea for more than 10 years. Our doctors, nurse practitioners and other staff members are experts in this area. We want families and patients to discuss different treatments and to ask questions.
To learn more, please call Nicklaus Children’s Hospital – Division of Hematology/Oncology at (305) 663-8528.
Reviewed by: Athena Pefkarou, MD
This page was last updated on: April 06, 2021 10:18 AM