Description, Causes and Risk Factors:
Blood is a constantly circulating fluid providing the body with nutrition, oxygen, and waste removal. Blood is mostly liquid, with numerous cells and proteins suspended in it, making blood "thicker" than pure water. The average person has about 5 liters (more than a gallon) of blood.
A liquid called plasma makes up about half of the content of blood. Plasma contains proteins that help blood to clot, transport substances through the blood, and perform other functions. Plasma also contains glucose and other dissolved nutrients.
About half of blood volume is composed of blood cells:
Red cells, which carry oxygen to the tissues.
- White cells, which fight infections.
- Platelets, smaller cells that help blood to clot.
It is conducted through blood vessels (arteries and veins). It is prevented from clotting in the blood vessels by their smoothness, and the finely tuned balance of clotting factors.
Iron deficiency anemia is probably the most common blood disorder in adolescents. Less common is sickle cell disease and thalassemia. Fortunately, leukemia, which is a cancer of the blood, is even less common.
Bleeding disorders occur in adolescents. In one recent study, a bleeding disorder accounted for a common cause of heavy menstrual periods in adolescent girls.
Blood clotting or hemostasis depends on an interaction between blood platelets, blood vessels and coagulation proteins or factors. When an adolescent sustains a cut, a series of events is initiated to establish blood clotting. Platelets produce a platelet plug and this is termed the primary hemostatic mechanism. The coagulation mechanism, which includes the blood factors, is activated at the same time. Blood factors are produced in the liver and are labeled with a roman numeral. These factors may include:
Factor I or Fibrinogen.
- Factor II or Prothrombin.
- Factor V or Labile factor.
- Factor VII or Stable factor.
- Factor VIII or Antihemophilic factor.
- Factor IX or Christmas factor.
- Factor X or Stuart-Power factor.
- Factor XI or Plasma thromboplastin antecedent.
- Factor XII or Hageman factor.
- Factor XIII or Fibrin-stabilizing factor.
Platelets have a life span of approximately ten days and are produced in the bone marrow. The liver synthesizes the coagulation factors. By activation of the factors, a blood protein called fibrin forms a stable hemostatic plug at the site of the platelet plug.
The sequence of events that leads to hemostasis is complex. There are a number of clotting factors that need to be activated in what is termed the waterfall cascade. These clotting factors are normally inactive, but become activated during the waterfall cascade. The activated clotting factor will then initiate the activation of the next clotting factor in the sequence. This allows for hemostasis at the area of injury.
A teen who has a problem with the function or number of platelets may be at risk for bleeding. A condition called idiopathic thrombocytopenic purpura is characterized by a marked deficiency of platelets in the bloodstream even though there are adequate numbers of megakaryocytes, which are the cells that form platelets in the bone marrow. An adolescent may also have a low platelet count due to a medication, autoimmune disease or even through an inherited mechanism. Platelets may also not function properly, and toxic substances could cause this from kidney
failure or drugs.
An adolescent may also be at risk for a bleeding disorder if he or she has an inherited hemophilia. For example, hemophilia A is due to deficiency of Factor VIII, Hemophilia B is due to deficiency of Factor IX and Hemophilia C is due to deficiency of Factor XI. Hemophilia A and B are seen only in males, while Hemophilia C is seen in both male and females.
Since the liver produces factors, then liver disease may cause a deficiency of these blood factors. As a result, teens that have liver failure due to such illnesses as Hepatitis B or C may be at risk for bleeding disorders.
Bleeding due to a platelet problem may be sudden or insidious. A teen may have small or large bruises under the skin, heavy menstrual periods, bruising after modest injury or nosebleeds. A teen that has inherited a bleeding disorder, such as hemophilia A, will have had a history of bleeding after injury. These teens may bleed into knee joints, have large bruises and bleed after blood tests.
The clinical history provides the most useful information for the teen with a bleeding disorder. Important information includes any previous history of bleeding, medications, sites of bleeding and the severity of the hemorrhage. Inquiry is made into a history of heavy menstrual periods, bleeding after surgery or dental procedures.
A physical examination usually focuses on whether the bleeding is superficial such as under the skin or from the mucous membranes or deep in the tissues. Deep bleeding occurs in muscles and into joints. Adolescents with hemophilia usually have symptoms and signs of deep bleeding.
The laboratory examination includes tests of platelet and factor function. Typically, the clinician will do a complete blood count, platelet count and certain bleeding tests to determine factor function. The blood levels of factors may be determined as well as the presence of inhibitors against the clotting sequence.
The treatment of a bleeding disorder depends on its cause. Idiopathic thrombocytopenic purpura is usually self-limited. Within nine to twelve months, the platelet count has returned to normal in about ninety percent of teens. Occasionally steroid therapy may be used depending on the severity of the bleeding issues and the platelet count.
Since hemophilia A is due to a deficiency of Factor VIII, therapy is aimed to increase Factor VIII activity in the plasma. This is done by the infusion of Factor VIII concentrates into the teen's bloodstream. Most adolescents can manage their hemophilia with home treatment and this allows more independence for the teen, maintenance of self-esteem as well as earlier treatment of bleeding episodes. Teens with Hemophilia B may receive Factor IX by infusions of fresh frozen blood plasma or a concentrate with Factor IX. Boys and girls with hemophilia C may receive replacement factor from fresh frozen plasma. Treatments are available for other bleeding disorders.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.