Secondary Thrombocytosis - Abnormal Platelet Count

What Are Platelets?

Platelets are a type of blood cell formed in spongy tissues by the stem cells or hemopoietic cells of the bone marrow and are present in the plasma of the blood. They are also known as thrombocytes. These thrombocytes are tiny, disc-shaped, pale, or colorless cells whose function in the clotting process is the formation of clots and stopping the bleeding at the site of injury. The normal platelets count is 150,000/microliters to 450,000/microliters. There are several platelet count-related disorders: thrombocytosis refers to the increased production of platelets, and thrombocytopenia refers to decreased production of platelets.

What Is Thrombocytosis?

Thrombocytosis is a blood disorder involving an increased count of platelets due to some underlying diseases and is also called thrombocythemia. Thrombocytosis can also be caused by genetic inheritance due to mutation in the Von Willebrand factor gene. It is divided into two groups such as primary and secondary thrombocytosis (reactive thrombocytosis). Dark-colored bruises on the skin, abdominal bleeding, and bleeding from the nose and gums are seen in thrombocytosis.

What Is Secondary Thrombocytosis?

Secondary thrombocytosis is a common blood disorder related to the increased proliferation of platelets due to some underlying disorders or the use of some medication, which leads to excessive clotting or bleeding, involving 70 to 90 percent of thrombocytosis cases.

What Are the Causes of Secondary Thrombocytosis?

The leading causes of thrombocytosis are some systemic underlying disorders involving:

• Leukemia.

• Acute Infections like bacterial and viral.

• Chronic Infections like tuberculosis.

• Inflammation.

• Hemorrhage.

• Iron deficiency.

• Anaphylactic reactions.

• Splenomegaly (removal of the spleen).

• Rheumatoid arthritis.

• Drug administration such as Aztreonam, Ceftazidime, Ibuprofen, Epinephrine, and Glucocorticoids.

• Inflammatory bowel disease.

• Sarcoidosis.

• Trauma.

• Excessive exercise.

• Hemolysis (destruction of red blood cells).

What Is the Epidemiology of Secondary Thrombocytosis?

Secondary thrombocytosis is more commonly seen than primary thrombocytosis; it is mainly caused due to some other related disorders. For example, 75 percent of individuals have secondary thrombocytosis due to splenectomy; in individuals with iron deficiency, around 30 percent will develop secondary thrombocytosis. There is no preference for race, sex, or age in secondary thrombocytosis.

What Is the Pathophysiology of Secondary Thrombocytosis?

The excessive production of platelets causes thrombocytosis, whereas stem cells produce platelets in the bone marrow. These stem cells transfer into large cells called megakaryocytes.

Megakaryocytes release their fragments in the form of platelets, and these megakaryocytes can produce around 5000 to 10000 platelets. In conditions like secondary thrombocytosis, there is an overproduction of proteins like thrombo protein, interleukin-6, cytokines, or catecholamine in inflammatory reactions due to underlying conditions or neoplastic activities. Because of the overproduction of these proteins, there can be several changes in the bone marrow, and platelets may crowd other cells. Some other reasons, like an iron deficiency, can lead to excessive megakaryocytic proliferation, and removal of the spleen causes decreased platelet sequestration leading to thrombocytosis.

What Are the Signs and Symptoms of Secondary Thrombocytosis?

Patients with secondary thrombocytosis are mostly asymptomatic and may get detected by routine blood investigations.

Following are the signs and symptoms that can be seen in secondary thrombocytosis:

• Anemia.

• Excessive bleeding.

• Dizziness.

• Fatigue.

• Confusion.

• Shortness of breath.

• Chest pain.

• Seizures.

• Joint pain.

• Abdominal discomfort.

• Vomiting and nausea.

• Weight loss.

• Malignancy

• Night sweats.

• Enlarged spleen.

• Iron deficiency.

How to Evaluate the Patient With Secondary Thrombocytosis?

Evaluating patients with secondary thrombocytosis by physical examination and history taking.

Evaluation of History Involves:

• Family history (secondary thrombocytosis can be genetically transmitted).

• Durg history (involves the intake of certain drugs inducing secondary thrombocytosis).

• Surgical history (removal of the spleen).

• Personal habits like smoking and consumption of alcohol.

• External symptoms like fatigue, confusion, bleeding, abdominal discomfort, and other systemic conditions.

• History of bleeding.

• Trauma.

Evaluation of Physical Examination:

• Lymphadenopathy (involvement of lymph nodes).

• Dark-colored skin (bleeding beneath the skin).

• Hepatosplenomegaly (enlargement of the liver and spleen).

• Signs of arterial or venous thrombosis.

• Palpitations.

What Are the Investigations for the Diagnosis of Secondary Thrombocytosis?

Following are the investigations for the diagnosis of secondary thrombocytosis -

• Complete Blood Count (CBC) - To determine the platelet count in the blood.

• Peripheral Blood Smear - A blood sample is taken, and a slide is prepared to study the cell structures present in the blood under the microscope.

• Erythrocytes Sedimentation Rate (ESR) - It is advised to check the rate of red blood cells sedimented in the test tube; it can be used to determine anemia.

• C-Reactive Protein - It is a type of protein produced by the liver. The level of the gets increased at the time of inflammation.

• Serum Ferritin - This test is advised to check the body's storage and absorption of iron.

• D-Dimer - D-dimer is an enzyme that gets elevated at the time of inflammation.

• Bone Marrow Biopsy can also be advised.

What Are the Treatment Modalities for Secondary Thrombocytosis?

No specific treatment modalities are required for secondary thrombocytosis, as it is caused by some other underlying disorders. However, detecting the underlying cause can help in treating secondary thrombocytic. Through antiplatelets, drugs can be considered but may cause some other complications. In cases of iron deficiency, iron supplements are advised. Plateletpheresis can be done as a temporary relief to reduce excessive platelet count. Consultation with the specialist will help in the early detection of the underlying cause and can easily help get proper treatment and avoid other complications. Also, it will help maintain the platelet count's normal range.

What Is the Prognosis of Secondary Thrombocytosis?

Secondary thrombocytosis is curable by detecting and understanding the underlying causes of the disorder. However, the prognosis depends upon the curative measures taken for the treatment of the underlying disease.

What Are the Complications of Secondary Thrombocytosis?

Secondary thrombocytosis can lead to certain systemic complications involving life-threatening conditions as well.

• Thrombosis can lead to myocardial infarctions or pulmonary embolism.

• Miscarriages or abortions.

• Excessive bleeding.

• Malignancies.

• Intrauterine death of the fetus.

Conclusion

Thrombocytosis, also referred to as thrombocythemia, is a platelet disorder involving an excessive proliferation of megakaryocyte fragments forming platelets by the stem cells in the bone marrow. It is further divided into primary and secondary thrombocytosis. Secondary thrombocytosis is caused by other underlying disorders and can be treated as the cause is cured. Therefore the elevation of the platelets count is for several periods, which may not lead to other life-threatening conditions.