Platelets are a small, spherical/oval shaped component of our blood. Although derived from a cell structure, platelets themselves don’t have a nucleus.
Platelets are formed from small fragments found in bone marrow and play a vital role in the necessary function of blood clotting.
General platelet levels found in the bloodstream are between 150,000 and 450,000 per microliter of blood. Although there are several different factors that could influence a platelet’s expected life cycle, they normally survive within the body for 7 to 10 days.
What is the cause of a high platelet count? The medical term used to reference the appearance of a higher platelet count in the body is thrombocytosis.
Although the high end of the average platelet count can range from lab to lab, it is generally above 400,000 per microliter of blood.
Doctors can discover the presence of thrombocytosis through a routine blood sample. There are also blood tests specific to the counting of platelets.
The discovery of increased platelet levels can help in determining thrombocythemia and reactive thrombocytosis, which can possibly cause abnormal and unnecessary blood clotting.
With the information found below, we will further identify the conditions that can cause a platelet count to be higher than normal.
- Secondary (reactive) thrombocytosis
- Physiological thrombocytosis
- Primary (clonal) thrombocytosis
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A series of chronic and acute infections have been associated with the diagnosis of secondary, or reactive thrombocytosis. During the presence of acute infections, megakaryopoiesis can be inhibited.
This can happen due to a bacteria or viral infection and cause the body to have a higher platelet count than normal. Bacterial infections can include tuberculosis, chronic wound infections, osteomyelitis, purulent arthritis, pyelonephritis, and pneumonia, among others.
On the other hand, viral infections rarely reflect the presence of thrombocytosis.
Inflammatory disease can also lend to a higher platelet count.
Diseases such as liver cirrhosis, nephritis, inflammatory bowel disease, polyarteritis nodosa, rheumatic polymyalgia, and rheumatoid arthritis can all cause thrombocytosis.
Typically, the severity of the disease’s condition will correspond to with the effects of thrombocytosis. Proper treatment of the underlying inflammatory disease can help return platelet count to normal levels.
Iron deficiency anemia
A heightened platelet count is often found in patients that have sideropenic anemia, and more specifically iron deficiency anemia.
In these cases, a platelet count can be even greater than 1,000 x 10^9 per blood liter. Iron replacement therapy can help return the platelet count to an average level within 10 days.
Research has also discovered an association with neoplasms and high platelet counts, including pancreatic cancer, prostate cancer, lung cancer, mesothelioma, bladder, ovarian, non-Hodgkin’s lymphoma, and Hodgkin’s lymphoma.
90 percent of patients who have a high platelet count due to malignant disease present with a platelet count between 400 and 1,000 x 10^9 per blood liter.
Following a splenectomy a patient can develop a high platelet count that exceeds 1,000 x 10^9 per blood liter. Removing of the spleen is what causes thrombocytosis to develop.
After a few months, the platelet count will usually return to normal. If permanent thrombocytosis occurs following a splenectomy, thought should be given to the possible existence to conditions that may have developed such as ineffective erythropoiesis, hemolysis or myeloproliferative disorder.
Chronic myeloid leukemia
Thrombocytosis has been discovered in over two-thirds of patients who have chronic myeloid leukemia.
An elevated platelet count has also been observed in 66 percent of people who have polycythemia vera. 5 percent of these patients have a platelet count that exceeds 1,000 x 10^9 per blood liter.
Agnogenic myeloid metaplasia
Agnogenic myeloid metaplasia is also known as idiopathic myelofirbosis. This condition is often manifested in splenomegaly and anemia. Peripheral blood smear reviews often reveal the presence of leukerythroblastosis, which can be described as tear-like erythrocytes and an immature precursor of leukocytes and red blood cells.
High platelet counts have been discovered in over 33 percent of patients with these conditions. However, in more advanced stages of this disease, the finding of thrombocytopenia will be significant.
For many various types of myelodysplastic disorders, a high platelet is not usual. On the contrary, most patients actually display a lower than average platelet count. 5q-syndrome, a form of myelodysplastic syndrome, is only associated with high platelet count in 50 percent of patients.
Primary thrombocythemia, also known as essential thrombocytosis, is a type of chronic disease that is characterized as a myeloproliferative neoplasm. This relationship reveals an elevation in the number of platelets found in the blood.
The specific cause of this condition is not fully understood, but there is thought to be a certain level of genetic predisposition.
Some studies expose that primary thrombocythemia has only been diagnosed in every 6 out of 100,000 people per year. Females and males are equally affected by the condition.
However, in younger populations, females hold higher percentages. This disease is generally more prevalent in the older population – only 1 in 5 patients are younger than 40 years of age.
Although reactive thrombocytosis rarely is the cause of any symptoms, if symptoms do occur, it might be in the form of tingling and numbness of feet and hands, changes in vision, temporary loss of consciousness, chest pain, lightheadedness or dizziness, and headaches.
Treatment of high platelet levels will begin at the cause. If the cause of thrombocytosis is due to injury or a surgery that resulted in blood loss, the condition will not last long.
If the cause is an inflammatory disease or chronic infection, platelet levels can remain until the situation is controlled.
In many cases, a high platelet count will return to normal following successful treatment of the underlying cause. Still, impactful surgeries such as the removal of a spleen can cause a lifetime of thrombocytosis.
In cases such as this, your physician may prescribe aspirin in low doses to prevent blood clotting and bleeding. However, it should be noted that this rarely occurs in cases of reactive thrombocytosis.
Nevertheless, the patient should always remain cautious of blood clot symptoms in the presence of a high platelet count.