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Aug 22, 2006
Essential Thrombocytosis
by SirGan
 Although many have heard about it – not too many people know what exactly chronic myeloproliferative disorders are. Important thing to know is that these conditions result from the over-accumulation of blood cells. Major characteristic is that all these disorders begin with a change in the DNA of a blood-forming cell in the marrow, called a stem cell. There are three types of chronic myeloproliferative disorders:
All this is accompanied with overproduction of platelet-forming cells, called megakaryocytes, in the marrow. The function of the platelet-cell is to start the process of blood clotting in response to blood vessel injury. The platelet is also called a thrombocyte. The term thrombocythemia means an excess of platelets in the blood. Thrombocytosis is classified as two types:
What is essential thrombocythemia?Every patient should know that all blood cells begin as stem cells in the marrow and each stem cell has the potential to become a red cell, white cell, or platelet. Normally, some of the stem cells in marrow will develop into giant cells called megakaryocytes which all break up into small pieces and by this process produces several thousands of platelets. When we are talking about an essential thrombocythemia, we should know that there is an overproduction of megakaryocytes in the marrow, which in turn break up and release a greater than normal number of platelets into the blood. This could be a big problem because several researches done in the past have showed that these platelets may not function normally and can cause a blockage in blood vessels, known as a thrombus.
Incidence of the essential thrombocythemiaGood thing is that essential thrombocythemia is an uncommon disease. Several researches have proven that there is about 0.1 and 2.4 new cases per 100,000 people each year. It is proven that this condition mostly occurs in older children, but it is also commonly diagnosed in adult men and women.
Possible causes of essential thrombocythemiaThe most important thing to know about this disease is that it is one of several clonal diseases of the bone marrow. The term clonal means that the disease began with an acquired, genetic change in a single stem cell. This single stem cell is the parent of all the abnormal cells that develop and accumulate as part of the disease. Currently, the cause for the genetic change is unknown.
Secondary thrombocytosis may develop as a result of:
What are the symptoms and complications of essential thrombocythemia?Big diagnostic problem is the fact that many patients with essential thrombocythemia do not have any signs or symptoms. Other patients may have:
Uncontrolled essential thrombocythemia can cause pregnancy complications, including:
Thrombosis and bleeding- the most common complicationsEvery patient should know that the thrombosis is the most common complication of essential thrombocythemia. Another very common complication is bleeding. It is also proven that a blood clot can occur in either an artery or less frequently, in a vein. Of course- this could be extremely serious because if the clot blocks blood flow to an organ, such as the brain or heart causing a stroke and heart attack. Clotting complications may occur in patients with only a slightly elevated platelet count.
How is essential thrombocythemia diagnosed?Although it is really strange- the fact is that essential thrombocythemia is often identified completely accidentally in symptom-free patients when some routine blood test shows a higher than normal platelet count. Mildly enlarged spleen could also be easily found!
The platelet count is a medical blood test and the normal values range from about 175,000 to 350,000 platelets per microliter of blood. It is important to know that essential thrombocythemia is a consideration if:
Unfortunately- there are no specific tests that can be used to establish the diagnosis of essential thrombocythemia. Some of the routine tests that will probably be used as well as blood tests are a chest X-ray, an ultrasound or other scan of the abdomen, and a bone marrow test.
The bone marrow test involves taking both a liquid and a small pencil-lead like sample under a local anaesthetic from the bones at the back of the pelvis. Differential diagnosisEvery doctor should know that there are several conditions that can result in an increase in platelets, including:
In most cases, the diagnosis of essential thrombocythemia is made based on
How is a patient with essential thrombocythemia treated?Treatment decisions should be guided by the risk of clotting or bleeding complications in a patient. Physicians may use chemotherapy to reduce high platelet count in patients with previous bleeding or clotting episodes or those who are at high risk for such complications.
Risks for clotting complications include:
Risk factors for bleeding include:
MedicationsThe most commonly used drugs to treat essential thrombocythemia are:
· hydroxyurea (Hydrea)
· anagrelide
· interferon alpha
What is so special about this Hydroxyurea? Well, this is one very strong myelosuppressive agent that is can be used as initial therapy for essential thrombocythemia. Hydroxyurea often is successful in decreasing platelet count within several weeks, with few short-term side effects. However, every patient should know that there is some evidence that hydroxyurea is associated with an increased risk for developing acute leukemia after long-term therapy. Every patient should be aware of that fact! In rare cases where patients have life-threatening complications, the platelet count can be reduced rapidly using platelet aphaeresis -a procedure that removes platelets from the blood directly. Every patient should also know that Aspirin is widely used in essential thrombocytosis, particularly for symptoms likely to be due to clotting or overactive platelets. There are of course side effects of aspirin as it can cause bleeding and ulcers in the stomach and small intestine.
PrognosisIt is important to point out that the prognosis of children with Essential Thrombocytosis appears no different from that of adults. Adult patients have near-normal life expectancy because of the low rate of leukemic conversion. However, no child has been monitored long. The major morbidity factor is the increased risk of hemorrhagic complications. Essential thrombocytosis is a slowly progressive disorder with long asymptomatic periods punctuated by thrombotic or hemorrhagic events. The average survival of patients with this disorder is 12 to 15 years, and may be much longer in younger patients.
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