What is the normal platelet count?

In an adult, a normal count is about 150,000 to 450,000 platelets per microliter (x 10 6 /Liter) of blood.

If platelet levels fall below 20,000 per microliter, spontaneous bleeding may occur and is considered a life-threatening risk .Patients suffering from dengue hemorrhagic fever,have a high possibility of spontaneous bleeding and must be manage promptly and accordingly. It is the usual practice to monitor the platelet count every 24 hours if a patient is being suspected to have the dengue virus once the platelet falls lower than 200,000 /mcl, and a reading below 150,000 is usually advised admission to a hospital for further evaluation and management.
In patients who have a bone marrow disease, such as leukemia or another cancer in the bone marrow, often experience excessive bleeding due to a significantly decreased number of platelets (thrombocytopenia). As the number of cancer cells increases in the bone marrow, normal bone marrow cells are crowded out, resulting in fewer platelet-producing cells.

Low number of platelets may be seen in some patients with long-term bleeding problems (e.g., chronic bleeding stomach ulcers), thus reducing the supply of platelets. Decreased platelet counts may also be seen in patients with Gram-negative sepsis