How and where are platelets produced in the body and what is their role during homeostasis?
Platelets are also known as thrombocytes and result from disintegration of certain large cells in the red bone marrow (1).
There are three processes involved in homeostasis:
- Constriction of blood vessels.
- Activity of platelets and;
- Activity of blood clotting factors.
Platelets are stimulated when a blood vessel wall breaks from injury. They are originally round but change to a spiny shape and are able attach themselves to each other and to the vessel wall that is broken, acting as a plug. In addition, they work together with other blood proteins to form fibrin. A net is formed by the fibrin strands that traps platelets and blood cells, forming a clot that blocks the break. The clotting formed is therefore balanced by the clotting that is stopped when the vessel is healed (1).
What are the potential consequences of a low platelet count?
Skin bleeding might be the initial indication of a low platelet count. Petechiae or tiny red dots frequently become visible in the skin on the lower legs, and slight injuries may cause little bruises to spread. Gums may bleed, and there may be blood in the stool or urine. Menstrual periods may be abnormally intense. Bleeding may be difficult to stop (1).
What is thrombocytopenia and what are the common causes of this condition?
Thrombocytopenia is a shortage of platelets and can be caused by many diseases namely:
- Leukemia and some anemia (bone marrow does not produce sufficient platelets)
- HIV virus
- Myelofibrosis and Gaucher’s disease (platelets become trapped in an enlarged spleen and diminish the amount of platelets in the bloodstream)
- Immense blood transfusions can weaken platelet concentration in the blood Idiopathic thrombocytopenic purpura, thrombotic thrombocytopenic purpura, and hemolytic- uremic syndrome (body can use or destroy too many platelets) (1).
What drugs are associated with the development of thrombocytopenia and how is thrombocytopenia treated in individuals?
These drugs include: heparin, quinidine, quinine, sulfa-containing antibiotics, and some oral drugs for diabetes, rifampin and gold salts (1).
If a drug caused thrombocytopenia it is normally rectified by discontinuing the drug. Corticosteroids or intravenous immune globulin can be used to temporarily block the effects that destroy platelets in ITP therefore permitting the number of platelets to increase. Many adults (but not children) with ITP ultimately need the spleen to be surgically removed of to improve the number of platelets. People with TTP are frequently treated with plasma transfusions together with plasmapheresis (1).
How does the removal of the spleen help to increase the number of circulating platelets?
The spleen’s function is to remove antibodies included in the red blood cells (RBC). Therefore by surgically removing the spleen; there will not be a production of protective humoral antibodies aimed at the autoantibody and platelets will increase (1).
What is Idiopathicthrombocytopenic purpura (ITP)?
Idiopathic thrombocytopenic purpura is a bleeding disorder brought about by thrombocytopenia that is not connected with a general disease. Usually, it is chronic in adults although is typically acute and self-limited in children. ITP results from antibody development aimed at an autoantibody. In childhood ITP the autoantibody may be set off by fastening of viral antigen to megakaryocytes (1)
Resource:
- The Merck Manuals. Online MedLibrary (1995-2007). Hematology and Oncology.
