Glossary - Hematology and Blood Disorders in Children

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A

Acute - severe, sharp, begins quickly.

Acute lymphocytic leukemia (ALL) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) lymphocytes, a type of white blood cell, are found in the bone marrow, blood, spleen, liver, and other organs.

Acute myelogenous leukemia (AML) - a rapidly progressing cancer of the blood in which too many immature (not fully formed) granulocytes, a type of white blood cell, are found in the bone marrow and blood.

Adjuvant therapy - treatment used in addition to the main (primary) treatment. Adjuvant therapy usually refers to hormonal therapy, chemotherapy, radiation therapy, or immunotherapy added after surgery to increase the chances of curing the disease or minimizing symptoms.

Allogeneic bone marrow transplantation - a procedure in which a person receives stem cells from a compatible donor.

Anemia - a blood disorder caused by a deficiency of red blood cells or hemoglobin (the oxygen-carrying protein in red blood cells).

Apheresis - a procedure in which a patient's own blood is removed, the desired particular fluid and cellular elements are extracted from the blood, and then it's returned to the patient.

Aplastic anemia - one type of anemia that occurs when the bone marrow produces too few of all three types of blood cells: red cells, white cells, and platelets.

Autologous bone marrow transplantation - a procedure in which a patient's own bone marrow is removed, sometimes treated with anticancer drugs or radiation, then returned to the patient.

Autosomal recessive inheritance - a gene on one of the first 22 pairs of chromosomes, which, when present in two copies, causes a trait or disease to be expressed.

B

Barium swallow/upper GI series - a diagnostic test that examines the organs of the upper part of the digestive system: the esophagus, stomach, and duodenum (the first section of the small intestine). A fluid called barium (a metallic, chalky, liquid used to coat the inside of organs so that they will show up on an X-ray) is swallowed. X-rays are then taken to evaluate the digestive organs.

Blasts - immature blood cells.

Blood - the life-maintaining fluid which is made up of plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets; blood circulates throughout the entire body; it carries away waste matter and carbon dioxide, and brings nourishment, electrolytes, hormones, vitamins, antibodies, heat, and oxygen to the tissues.

Blood banking - the process that takes place in the laboratory to ensure that the donated blood or blood products are safe, before they're used in blood transfusions and other medical procedures. Blood banking includes typing and cross matching the blood for transfusion and testing for infectious diseases.

Bone marrow - the soft, spongy tissue found inside bones. It's the site of development and storage of about 95 percent of the body's blood cells.

Bone marrow aspiration and biopsy - the marrow may be removed by aspiration or a needle biopsy under local anesthesia. In aspiration biopsy, a fluid specimen is removed from the bone marrow. In a needle biopsy, marrow cells (not fluid) are removed. These methods are often used together.

Bone marrow transplant (BMT) - the transfusion of healthy bone marrow cells into a person after their own unhealthy bone marrow has been eliminated.

C

Clotting - the sealing of a blood vessel with coagulated blood.

Chronic myelogenous leukemia (CML) - a slowly progressing cancer of the blood in which too many white blood cells, called granulocytes, are produced in the bone marrow.

Complete blood count (CBC) - a measurement of size, number, and maturity of the different blood cells in a specific volume of blood.

D

E

F

Factor - a protein in the blood that's needed to form the blood clot.

Folic acid deficiency - a deficiency in a B vitamin known as folic acid, which can cause megaloblastic anemia.

G

Gene - a segment of DNA that codes for a trait such as blood type or eye color, as well as susceptibility to certain diseases.

Graft-versus-host disease (GVHD) - the condition that results when the immune cells of a transplant (usually of bone marrow) from a donor attack the tissues of the person receiving the transplant.

Granulocytes - a type of white blood cell that helps the body fight infection. The types of granulocytes include: basophils, eosinophils, and neutrophils.

H

Hemarthrosis - bleeding into a joint.

Hematocrit - the measurement of the percentage of red blood cells in a specific volume of blood.

Hematologist - a physician who specializes in the functions and disorders of the blood.

Hematology - the scientific study of blood and blood-forming tissues.

Hematopoiesis - the process of producing and developing new blood cells.

Hemoglobin - a type of protein in the red blood cells that carries oxygen to the tissues of the body.

Hemoglobin S-beta thalassemia - having one copy of the gene which causes sickle cell anemia (HbS) and one copy of a mutated gene in the beta-chain of hemoglobin; this blood disorder produces a moderate anemia and some symptoms similar to sickle cell anemia.

Hemolysis - the destruction of red blood cells by the body.

Hemolytic anemia - one type of anemia in which the red blood cells are destroyed prematurely.

Hemophilia (Also called a coagulation disorder.) - an inherited bleeding disorder caused by low levels, or absence of, a blood protein that is essential for clotting; hemophilia A is caused by a lack of the blood clotting protein factor VIII; hemophilia B is caused by a deficiency of factor IX.

Hemorrhagic anemia - anemia caused by a sudden loss of a large amount of blood.

I

Immune system - the system composed of lymph fluid, lymph nodes, the lymphatic system, white blood cells, and certain organs that are responsible for protecting the body against infection and disease.

Immune thrombocytopenic purpura (ITP) - a blood disorder characterized by an abnormal decrease in the number of blood platelets, which results in internal bleeding. There are two forms of ITP: acute ITP and chronic ITP.

Immunosuppression - a state in which the ability of the body's immune system to respond is decreased. This condition may be present at birth, or it may be caused by certain infections (such as human immunodeficiency virus, or HIV). It may also be caused by certain cancer therapies, such as cancer cell killing (cytotoxic) drugs, radiation, and bone marrow transplantation.

Immunotherapy - treatments that promote or support the body's immune system response to a disease such as cancer.

Intravenous gamma globulin (IVGG) - a protein that contains many antibodies and slows destruction of platelets; used in the treatment of ITP and other disorders.

Iron deficiency anemia - the most common type of anemia. It's caused by a lack of iron in the blood, which is necessary to make hemoglobin.

J

Jaundice - yellowing of the skin, eyes, and oral mucosa.

K

L

Leukemia - a cancer of the blood-forming tissue. Leukemic cells look different than normal cells and don't function properly.

Lymph - part of the lymphatic system; a thin, clear fluid that circulates through the lymphatic vessels and carries blood cells that fight infection and disease.

Lymph nodes - part of the lymphatic system; bean-shaped organs, found in the underarm, groin, neck, and abdomen, that act as filters for the lymph fluid as it passes through them.

Lymph vessels - part of the lymphatic system; thin tubes that carry lymph fluid throughout the body.

Lymphangiogram (LAG) - an imaging study that can detect cancer cells or abnormalities in the lymphatic system and structures. It involves a dye being injected to the lymph system.

Lymphatic system - part of the immune system; includes lymph, ducts, organs, lymph vessels, lymphocytes, and lymph nodes, whose function is to produce and carry white blood cells to fight disease and infection.

Lymphocytes - part of the lymphatic system; white blood cells that fight infection and disease.

Lymphocytic leukemia - a type of leukemia in which the cancer develops in the lymphocytes (lymphoid cells).

M

Megaloblastic anemia - a rare blood disorder caused by a deficiency of either folate (a B vitamin) or vitamin B₁₂, resulting in an inadequate amount of red blood cells produced.

Mucositis - inflammation of the mouth and gastrointestinal tract.

Mutation - a change in a gene.

Myelogenous leukemia - a type of leukemia in which the cancer develops in the granulocytes or monocytes (myeloid cells).

Myeloproliferative disorders - diseases in which the bone marrow produces too many of one of the three types of blood cells: red blood cells, which carry oxygen to all the tissues in the body; white blood cells, which fight infection; and platelets, which makes blood clot.

N

O

P

Pernicious anemia - a type of megaloblastic anemia in which the body doesn't absorb enough vitamin B₁₂from the digestive tract.

Petechia - tiny red dots under the skin that are the result of very small bleeds.

Plasma - the watery, liquid part of the blood in which the red blood cells, the white blood cells, and platelets are suspended.

Platelet pheresis - a procedure to remove extra platelets from the blood.

Platelets - cells found in the blood that are needed to help the blood to clot in order to control bleeding; often used in the treatment of leukemia and other forms of cancer that cause low platelet counts.

Pluripotent stem cell - the most primitive, undeveloped blood cell.

Purpura - the purple appearance of skin after blood has "leaked" under it.

Q

R

Red blood cells (Also called RBCs or erythrocytes.) - blood cells that mainly help transport oxygen to all the tissues in the body.

S

Sickle cell anemia - an inherited blood disorder characterized by defective hemoglobin, where there are two copies of abnormal hemoglobin genes present.

Sickle cell - hemoglobin C disease - having one copy of the gene which causes sickle cell anemia (HbS) and one copy of another altered hemoglobin gene (HbC); this blood disorder is similar to sickle cell anemia.

Sickle cell - hemoglobin E disease - having one copy of the gene which causes sickle cell anemia (HbS) and one copy of another altered hemoglobin gene (HbE); this blood disorder may or may not cause symptoms except under stress (exhaustion, infection, etc.).

Sickle cell trait - having one copy of the gene which causes sickle cell anemia (HbS), and one copy of the normal hemoglobin gene.

Stem cells - the blood cells that produce other blood cells. It's the stem cells that are needed in bone marrow transplantation.

Sickle crisis (Also called pain crisis or vasoocclusive crisis.) - in sickle cell diseases, the pain that occurs when the flow of blood is blocked to an area because the sickled cells are stuck in a blood vessel.

T

Thalassemia - an inherited blood disorder in which the chains of the hemoglobin (a type of protein in red blood cells that carries oxygen to the tissues) molecule are abnormal; alpha thalassemia is where a mutation occurs in the alpha chain, while beta thalassemia is where the mutation occurs in the beta chain; signs and symptoms of thalassemias vary from mild (little to no symptoms) to severe (life threatening). Also called Cooley's anemia.

U

V

Von Willebrand disease - a mild form of hemophilia caused by an abnormality in the von Willebrand factor, which is necessary for platelets to be able to attach themselves to a vein or artery to form a clot to stop bleeding.

W

White blood cells (Also called WBCs or leukocytes) - blood cells involved in the destruction of viruses, bacteria, and fungi which cause infection.

X

Y

Z