Thrombocytopenia, Low Platelet Count and Bleeding Problems
Blood platelets play a vital role in blood clotting and wound healing. The body has to regulate their numbers very carefully. If someone has too many platelets, blood clots may form where they don’t belong, obstructing blood flow. If a person has too few platelets, they may bleed to death from an injury.
Platelets are also known as thrombocytes. Thrombocytopenia is a condition in which the blood has a low platelet count. Blood platelets are made in the bone marrow, along with red and white blood cells. Thrombocytopenia can develop if the bone marrow doesn't make enough platelets or if the platelets are destroyed after they have formed. Thrombocytopenia is often a mild or moderately severe disease, but sometimes it's a serious condition. The treatment depends on the severity of the disorder.
Platelets and their Manufacture
There are two types of bone marrow - red and yellow. Red bone marrow makes platelets and blood cells. Yellow bone marrow stores fat instead. Large cells in the red bone marrow called megakaryocytes release cell fragments, which become the platelets.
Platelets are much smaller than red blood cells and white blood cells and have a flat, disc shape until they are activated. They were given their name by earlier scientists, who thought that they looked like tiny plates. Platelets normally live for seven to ten days.
Structure of a Typical Bone
Function of Platelets
The endothelium is the internal lining of the blood vessels. When the endothelium is damaged, chemicals which attract and activate platelets are exposed. As platelets are activated they change their shape. They become spherical and produce tentacle-like extensions. The activated platelets stick to each other and to the wound, forming a platelet plug that stops the bleeding from the wound. The activated platelets and proteins in the blood then work together to create a blood clot through a series of chemical reactions. The final reaction is the conversion of a dissolved blood protein called fibrinogen into solid fibrin threads, which form a mesh over the wounded area, trapping blood and platelets in a blood clot.
Platelets and Blood Clotting
The Platelet Count
Human blood normally contains between 150,000 to 450,000 platelets in each microliter of blood. If someone’s platelet count is below 150,000 per microliter of blood, he or she is said to suffer from thrombocytopenia. A mild case of thrombocytopenia may not produce any symptoms. When the platelet count is reduced to around 50,000 platelets per microliter of blood, the person may experience minor bleeding problems. A platelet count of below 20,000 platelets per microliter of blood will cause serious symptoms.
Causes of Thrombocytopenia
If the bone marrow doesn’t make enough platelets or if platelets are destroyed once they are made, thrombocytopenia may result. Excessive storage of blood in the spleen can also cause the disorder.
There are many factors that can lower the platelet level in the blood. The main ones are listed below, but there are others.
Platelet Manufacture Problems
There are a range of factors that can interfere with the manufacture of platelets in the bone marrow.
- Someone with thrombocytopenia may have inherited a genetic problem that prevents him or her from making enough platelets.
- Alcohol and poisonous chemicals like arsenic, benzene and some pesticides can slow platelet production.
- Some types of diuretics and epilepsy drugs will also interfere with platelet manufacture.
- In a disease called aplastic anemia the bone marrow doesn’t make enough blood cells or platelets.
- A deficiency in vitamin B12 and folic acid can reduce platelet manufacture.
- Cancer and cancer treatments can damage bone marrow and stop it from making blood platelets.
- An HIV, parvovirus or hepatitis C virus infection can decrease platelet production.
- Certain viruses can lower the platelet count. These include the Epstein-Barr virus, which causes mononucleosis and other health problems, the viruses that cause chickenpox, rubella (German measles) and mumps, and the virus that causes dengue fever.
- Some bacterial infections in the blood also lower the platelet count.
In some cases, platelets are formed normally but are then destroyed.
- The use of heparin, quinine, sulfa antibiotics and some epilepsy drugs can lead to platelet destruction.
- Aspirin, ibuprofen and some antihistamines stop platelets from working normally, which can increase bleeding.
- Platelets may be destroyed in rheumatoid arthritis and lupus.
- Autoimmune diseases are conditions in which a person’s body attacks its own cells. If these cells are platelets, thrombocytopenia can result.
- The body destroys platelets in a disorder called idiopathic thrombocytopenic purpura (ITP). The condition is also known as immune thrombocytopenic purpura. “Purpura” means “bruises", referring to the bleeding under the skin that appears during this disease. The term "idiopathic" means that the exact cause of the disorder is unknown. It is known that the immune system attacks and destroys platelets, however.
- Some women develop mild thrombocytopenia close to the end of their pregnancy, for an unknown reason.
- Thrombocytopenia may develop in a fetus if the mother suffers from certain infections, including rubella and toxoplasma. It may also occur when the mother's body mistakenly makes antibodies that cross the placenta and destroy the baby's platelets.
What are Fetal and Neonatal Thrombocytopenia?
Spleen Problems and a Low Platelet Count
The spleen, which is located on the left side of the upper abdomen under the ribcage, normally stores up to one third of the platelets in the body. If the spleen is enlarged it will store too many platelets and a low blood platelet count will result.
An enlarged spleen is a symptom of many disorders, such as viral and bacterial infections, some types of anemia, liver diseases and some types of cancer. We can live well without a spleen, so sometimes it's removed from the body when it's causing problems.
Difference Between Purpura and Petechiae
Purpura is a skin rash that consists of purple or red spots on the skin. The spots are areas where bleeding is occurring under the skin. If the spots are less than three millimetres in diameter, they are known as petechiae. In this case the rash may be known as a petechial rash.
Possible Symptoms of Thrombocytopenia
Internal or external bleeding is the main symptom of thrombocytopenia. It's important to note that the symptoms below may be caused by a condition other than a low platelet count. They may be the result of a relatively minor problem, but it's still important to pinpoint their cause.
A person with thrombocytopenia may have a rash made of red or purple spots on the skin, a condition known as purpura. The spots are caused by bleeding under the skin. The person may also find that they bleed a long time often even a small cut. Their gums may bleed after they brush their teeth or after they visit a dentist. The gums may bleed even without any mouth irritation. In addition, the person may have bad nosebleeds. In women, menstrual blood flow may be heavy.
There may be blood in the affected person's urine or stool or bleeding from the rectum, which may indicate internal bleeding. In very severe thrombocytopenia there may be bleeding from the brain or heavy digestive tract bleeding. These are serious symptoms and may be life threatening. Many cases of thrombocytopenia are less severe, however.
Possible Treatments for Thrombocytopenia
You should see your doctor if you have any signs of increased bleeding. The doctor will make a diagnosis and prescribe treatment. If you are found to have a mild case of thrombocytopenia you may not need treatment, but this decision needs to be made by your doctor.
More serious cases of thrombocytopenia will likely require some form of treatment. Medication may need to be changed or prescribed and infections will need to be treated. Drugs may be given to suppress the immune system or corticosteroids may be prescribed to slow platelet destruction. Blood or platelet transfusion or spleen removal (splenectomy) may be necessary in severe cases.
Living Well with a Low Platelet Count
It's often possible to live well with a low platelet count if certain precautions are taken. If you have thrombocytopenia there are things that you can do to help yourself, even if you are receiving medical treatment.
- Avoid chemicals and medications which are known to hinder platelet production or destroy platelets, if possible.
- Eat nutritious foods and exercise regularly to boost your immune system and try to avoid infections.
- Tell your doctor about any supplements or herbal medicines that you are taking, since some of them may affect the blood platelet level.
- Try to avoid injuries as much as possible. Ask your doctor whether participating in contact sports or sports with a high risk of injury, such as skiing, are appropriate activities for you.
- Wear protective gloves, helmets or clothing when performing any activity that may cause an injury.
- Consider taking vaccines for illnesses known to lower platelet levels, if vaccines are available.
- Consider wearing a medic alert bracelet or ID.
By working with your doctor, you should be able to deal with thrombocytopenia in the best way possible.
© 2010 Linda Crampton
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