What Causes Low Platelets?

Platelets, also known as thrombocytes, are small, and irregularly-shaped anuclear cell fragments. The average lifespan of a platelet is about five to nine days. It’s important that the amount of platelets in an individual remain a certain number because if the number of platelets is too low, excessive bleeding can occur.

Thrombocytopenia is the term for a low platelet count. This can result from reduced platelet production or an increased rate of platelet destruction. There are various types of thrombocytopenias, one known as congenital thrombocytopenia, is a class of rare inherited diseases.

These diseases can range from the mild May Hegglin anomaly to the serious Bernard Soulier syndrome in which severe lifelong bleeding can occur. Another type of thrombocytopenia is defective platelet production. This can occur due to cancer cells reducing the number of megakaryocytes and thus the number of platelets produced.

The production process can also be interrupted by a host of other processes such as the side effects of chemotherapy drugs, viral infections such as HIV, as well as metabolic disorders. A third type of thrombocytopenia is diminished platelet survival. In this case the platelet count will be low if the platelets are being removed from the blood faster than they are being replenished.

Platelets are normally lost in clots or removed when they age, but this process can be amplified due to many diseases and drugs. These diseases include HIV, rheumatoid arthritis, systemic lupus erythematosis, meningitis, and chronic lymphocytic leukemia. Medicines such as the anti-malaria drug quinine can also cause diminished platelet survival.

What Are Platelets?

Platelets are produced in the bone marrow by budding off of precursor cells known as megakaryocytes. Their function is to form blood clots to prevent bleeding from a ruptured vessel. In the event of a bleed, platelets will stick to each other, as well as to the walls of the blood vessel, and release coagulation factors.

These factors will cause the blood to congeal around the area to prevent loss of blood. The blood clot will temporarily stop the bleed; however, vessel repair is required for a permanent solution. Platelets assist in this process by secreting chemicals that attract cells to fix the ruptured blood vessel.

Old platelets are destroyed by phagocytosis in the spleen. Platelets are present in the blood of an adult in the range of 150 to 400 million per milliliter of blood. Ninety-five percent of people have this range of platelets in their blood. It is possible to have an abnormal platelet count with no negative effects. However, if it is very low the likelihood of serious blood loss increases.

What to Do if You Have a Low Platelet Count

So what should you do if your platelet count is low? A doctor will typically use symptoms of bleeding, bruising, infection, medication or other medical problems to order a blood test. If the platelet count is very low a patient may be referred to a hematologist who can test the bone marrow.

The test will allow the hematologist to determine if platelets are being produced normally and if there are any other bone marrow problems. Treatment for a low platelet count will depend on the severity. In general low platelet counts will not be corrected by blood transfusion, where platelets are injected into the blood stream, unless the level is below 5 million platelets per milliliter of blood.

A transfusion may also be given if there is risk of bleeding in the head or in the digestive tract as both of these are life threatening bleeds. If there is no need for a transfusion the treatment will focus on correcting the underlying cause of the low platelet count. Finally, the low platelet count may not cause any problems and would be monitored yearly to ensure the health of the person.