Bruises are hardly unusual in children as they tend to fall down, run into each other and bump the furniture regularly. But bruising that occurs spontaneously or that seems out of proportion to an injury needs investigation. Many diseases can cause easy bruising in children; some are temporary and not serious, while others need ongoing medical treatment. Blood tests can can help identify diseases that cause easy bruising in children.
Hemophilia
There are two types of hemophilia, an inherited clotting disorder. Nearly all of the 400 children born with hemophilia each year in the United States are boys. Nine out of 10 have hemophilia A rather than B. Proteins called clotting factor that help the blood clot are absent in children with hemophilia; in hemophilia A, factor VIII is missing, and in hemophilia B, factor IX is the absent protein. Clotting factors help blood cell fragments called platelets clump together at the site of an injury to stop bleeding.
Although hemophilia can range from mild to severe, seven out of 10 children have the severe form in which only 1 percent of the normal amount of clotting factor appears in the blood, says the National Heart Lung and Blood Institute. Many children with hemophilia receive regular injections of clotting factor, since bleeding into the joints and other areas of the body that may not be immediately noticed can be extremely dangerous.
Idiopathic Thrombocytopenia (ITP)
ITP in children usually occurs between the ages of 2 and 4, and as the name suggests, the cause is idiopathic, or unknown. ITP occurs when platelet levels are lower than normal, so bruising with minimal or no injury occurs. Platelets stick together at the site of an injury to stop bleeding. In addition to bruising, ITP causes small pinpoint red dots on the skin called petechiae. Petechiae occur when very small blood vessels called capillaries bleed under the skin. In 80 percent of children, ITP lasts six months or less and then spontaneously disappears, according to the American Academy of Family Physicians' site, Family Doctor.
Leukemia
Leukemia is the most common type of childhood cancer, according to Children's Hospital of Philadelphia. It affects the production of blood cells in the bone marrow. Immature cells grow out of control, crowding out normal production of white and red blood cells and platelets. Leukemia normally occurs in children between 2 and 6 years old, but can affect children of any age. Boys are slightly more likely to develop leukemia than girls, and Caucasian children have leukemia more often than black children.
In addition to bruising, fatigue, fever and shortness of breath often occurs in children with leukemia. There are several kinds of childhood leukemia, with acute lymphocytic leukemia, or ALL, comprising 80 percent of cases. Leukemia is not inherited and the causes are often unknown, although children with certain genetic abnormalities such as Down syndrome are more likely to develop it.
Von Willebrand Disease
Von Willebrand disease is the most common inherited bleeding disorder, Medline Plus, a website of the National Institutes of Health, reports. Von Willebrand factor helps platelets clump together and stop bleeding. This disease is usually mild, affects males and females equally, and is more common in Caucasians than blacks.
