PLATELET COUNT

In adults:

• 1.5-4 lakhs/mm³ of blood.

• Platelets are anuclear cytoplasmic fragments of megakaryocytes, 2-4 µm in diameter. They play an important role in haemostasis (the control of bleeding) and the formation of clots within the blood cells.
• They are developed from megakaryocytes, the giant cells in the bone marrow. The development of platelets is known as thrombopoiesis. Normally have a half life of about 4 days. Their survival time in circulation is about 8-12 days. Spleen is an important site of destruction of platelets.
• Platelets perform four main functions in the body: Temporary haemostasis (arrest of bleeding), Clotting of blood, Phagocytosis of small particles and organisms and Storage and transport of chemicals
• Platelet count is usually ordered as a part of the laboratory diagnosis of a bleeding disorder. When platelet count increases in the blood, the condition is known as thrombocytosis, and when the count decreases, the condition is called
• Thrombocytopenia can be caused by impaired production or increased destruction of the platelets. Prolonged bleeding time is the hallmark of thrombocytopenia. When platelet count is less than 50,000 per mm³ of blood, the count is called critical count, as bleeding may occur spontaneously. To differentiate the causes of thrombocytopenia, bone marrow should be carefully examined. If megakaryocytes are absent in the bone marrow, this implies failure of platelet production.

• Polycythemia vera
• Chronic myeloid leukemia
• Iron deficiency anemia
• Spleenectomy
• Chronic infection
• Surgery
• Acute haemorrhage
• Cancer (Lung, breast, ovarian, lymphoma)
• Rheumatoid Arthritis
• Myeloproliferative disorder

Thrombocytopenia

• Idiopathic thrombocytopenic purpura
• Aplastic anemia
• Hypersplenism
• Acute leukemia
• Cytotoxic chemotherapy
• Radiation treatment
• Viral Infection ( mononucleosis, measles, hepatitis)
• Auto immune disorders