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Parent and Caregiver Handbook for Sickle Cell

Appendix: Glossary of sickle cell terms

Acute Chest Syndrome

Pneumonia caused by infection and sickle cell damage or just sickle cell damage in the lungs. Signs of acute chest syndrome may include fever, chest pain, coughing, shortness of breath, or difficulty breathing. This is a medical emergency.

Anemia (low red blood cell count)

When there is less hemoglobin in the blood than usual so that the blood can’t carry as much oxygen.

Aplastic Episode

When the bone marrow stops making red blood cells. The blood count may fall much lower than usual. If it happens, it is usually with a fever or infection.

Avascular Necrosis

When sickle cell disease damages joints.


A person who has one gene for Hemoglobin A and one gene for another type of hemoglobin. This person is also referred to as having a hemoglobin trait. A carrier doesn’t have the disease, but two carriers can have a baby with sickle cell disease.


Structures containing the genes in the body. Most people have 46 chromosomes. Prenatal testing can be done to study the chromosomes of a fetus (developing baby) to determine their hemoglobin type.

Complete Blood Count (CBC)

A blood test that measures the size of the red blood cells and the amount of hemoglobin. It tells the number of red blood cells, white blood cells, and platelets.

Cross-Matching Blood

Before a blood transfusion, the blood bank mixes a sample of the donor blood with the blood of the person receiving a transfusion to check if the donor blood is a good match with the blood of the person who will receive it. A cross match is done with each transfusion. 


A condition caused by not having enough water in the body. Dehydration can happen with diarrhea, fever, or exercise. It may cause a sickling episode in someone with sickle cell disease.


One of the best blood tests to find out a person’s hemoglobin type. It shows most hemoglobin traits and can determine different types of sickle cell disease.

Exchange Transfusion

Blood transfusions can be given through an intravenous (IV) line to increase the hemoglobin to a normal level. They can also be done with a machine, which removes the sickle cell blood and replaces it with blood from donors. An exchange transfusion requires two IV lines: one to take the sickle blood out and one to transfuse the donor blood in.


Ferritin is the protein that carries iron in the body. Ferritin testing is used to show if the amount of iron in the blood is too high.


Genes are in our cells. They are the blueprint for our bodies. Genes are passed on by a mother in the egg and by a father in the sperm. People have about 35,000 genes that define many characteristics, including hemoglobin type.


The substance that carries oxygen in red blood cells. People with sickle cell disease often have lower hemoglobin levels.


A blockage of blood flow that causes tissue to die because it doesn’t have enough oxygen.


A characteristic passed on from parents to their children. Sickle cell disease is an inherited disease.


Yellowish color of the skin or eyes. It is caused by chemicals from red blood cell breakdown.

Leg Ulcer

A breakage in the skin that begins as a small sore on the lower leg (above, over and/or around the ankle). It can be caused by injury and decreased blood flow.

Neuropsychological Testing

This is testing done in young children or adolescents to find out how to help them if they are having a hard time in school. A specially trained psychologist will ask the child questions. There may be some questions for the child to read and then write answers. Sometimes testing can take as long as eight hours and has to be done in two sessions.

Pain Medication Dependency

When someone has taken pain medication for a long time and the pain has stopped, the doctor will gradually decrease the dose of medication to prevent a problem. Dependency is not the same as addiction.

Pain Medication Tolerance

Some medications become less effective if they have to be used for a long time. When that happens, higher doses are given to decrease the pain.

Pain Medication Withdrawal

Long-term use of some medications can cause the body to become used to it. This can cause stopping the medication suddenly to create discomfort. Withdrawal discomfort includes fatigue, upset stomach, anxiety, and trouble sleeping.


A persistent, painful, unwanted erection of the penis caused by sickling.

Prophylactic Penicillin

Penicillin that is given to reduce the number and severity of infections in children with sickle cell disease.

Pulmonary Hypertension

In sickle cell disease, sickling causes damage to the lungs If pulmonary hypertension results, the heart has to pump harder than usual to get blood to the lungs. An echocardiogram will help find out if pulmonary hypertension is happening.

Red Blood Cell Phenotyping

Before a blood transfusion, the blood bank matches the proteins in blood between a blood donor and the person getting a blood transfusion. They do this because people who lack certain proteins may have a transfusion reaction to that protein if they are given blood with that protein from a donor. 


When the back of the eye (retina) is damaged by blockage in the small blood vessels and scarring in that area. This can lead to poor vision and even blindness. After ten years of age, every person with sickle cell disease should see an eye doctor once a year.

Sickle Cell Anemia

Another name for SS disease, the most common type of sickle cell disease.

Sickle Cell Disease

A term for all types of sickle hemoglobin disorders, such as sickle cell anemia (SS), SC disease and S beta thalassemia disease.


An organ on the left side of the body that may be felt below the rib cage. It is a filter to remove bacteria and damaged red blood cells from the blood. This organ does not work well in sickle cell disease. It can trap blood and become enlarged.


Surgery to remove the spleen. This is done to cure the serious anemia that happens when blood is trapped in the spleen (splenic sequestration, see below).

Splenic Sequestration

A medical emergency in people with sickle cell disease that is caused by blood being trapped in the spleen very rapidly, depriving the rest of the body of blood. It can be life threatening.

Trait (see Carrier)


Blood from one person given to another person. People with sickle cell disease receive transfusions for many reasons, including because of a very low red blood cell count, to prepare for surgery or to treat certain complications of sickle cell disease.

Vaso-Occlusive Episode

Also called a pain episode. This can happen when sickle cells block the flow of blood. It causes pain and, if severe, tissue damage.

This glossary is provided courtesy of the University of San Francisco, Benioff Children’s Hospital Oakland Sickle Cell Center.​​

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