Thrombocytopenia means a decreased number of platelets (also called thrombocytes). Platelets are produced by megakaryocyte cells in the bone marrow and are necessary to help blood clot. Anytime a blood vessel is damaged and begins leaking blood, the odd shaped and sticky platelets clump together to plug the leak and prevent ongoing blood loss. Without a sufficient number of platelets, we would quickly bleed to death.
Thrombocytopenia can occur in HIV-positive people for a variety of reasons. First, it is known that HIV can infect megakaryocytes, which means that HIV itself can cause this condition. Second, certain drugs used to treat HIV/AIDS that can damage the bone marrow (e.g., some nucleoside reverse transcriptase inhibitors) and certain AIDS-related conditions (e.g., lymphoma and MAC), can result in decreased platelet production. Third, antibodies produced by the immune system can target healthy platelets in the body (a condition called immune thrombocytopenic pupura [ITP]). These antibodies are known as autoantibodies, as they are attacking the "self", and signal the spleen to destroy and remove the platelets from the body.
A normal platelet count is between 150,000 and 400,000 platelets per cubic milliliter of blood. In severe cases of thrombocytopenia, the platelet count can be close to zero. In mild cases, the platelet count is between 100,000 and 150,000. If the platelet count falls below 30,000, the risk of uncontrolled bleeding is high, including blood leakage in the brain (cerebral hemorrhage) that can lead to a stroke.
Platelets also carry serotonin and L-tryptophan, two substances involved in sleep/wake cycles, appetite, and mood regulation.
What are the symptoms and how is it diagnosed?
Many people with thrombocytopenia, especially mild thrombocytopenia, do not have any symptoms. More advanced forms of thrombocytopenia can cause a number of bleeding problems. These include excessive and recurrent nosebleeds (epistaxis), bruise-like patches (purpura), and excessive bleeding from wounds (hemorrhage).
A blood test to count platelets is the most important diagnostic tool to check for thrombocytopenia. Most HIV-positive people have their platelet levels checked on a regular basis, as part of their Complete Blood Count (CBC) Test, usually when viral load and T-cell counts are checked. In turn, most HIV-positive people are diagnosed with thrombocytopenia before it can cause serious problems.
How is it treated?
The most effective treatment for thrombocytopenia in HIV-positive people is anti-HIV drug treatment. Because anti-HIV drugs are effective in reducing the amount of virus in the blood, they can help prevent HIV from infecting megakaryocytes. Anti-HIV drug treatment can also help calm down the immune system, which may slow or stop the production of autoantibodies causing the thrombocytopenia.
If anti-HIV drug treatment is not effective, a number of other treatments are possible. These include:
Prednisone: Prednisone is a steroid medication that is similar to cortisone, a hormone that your adrenal gland produces. It has many uses, and is used to treat immune thrombocytopenic pupura (ITP) because it can calm down a hyperactive immune system and has been shown to increase platelet counts. Long-term prednisone use can suppress the immune system, which can be problematic for HIV-positive people.
Gamma Globulin (IVIg): IVIg is sometimes given alone or in combination with prednisone to increase the platelet count. It is given intravenously over four to six hours and is sometimes given for one to three days at a time.
Rh0 [D] Immune Globulin (WinRho®): WinRho®, also known as anti-D, is approved for people with Rh0 [D]-positive blood who have ITP. It contains antibodies specific to Rh0 antigen (also called the D antigen) located on red blood cells. These anti-D antibodies raise platelet counts by attaching or binding to the Rh0 antigen on red blood cells. The antibody-coated red blood cells temporarily prevent the spleen from destroying your platelets. It is given as an intravenous injection, once every month if needed.
Splenectomy: This is a surgery to remove the spleen. By removing the spleen, the organ responsible for removing platelets attacked by autoantibodies, ITP is theoretically cured. However, this approach is not usually recommended until other, less serious and less risky treatments have been tried.
Can it be prevented?
Thrombocytopenia can happen to anyone, although severe thrombocytopenia is considered to be rare among HIV-positive people. With the widespread use of anti-HIV drug treatment, it is likely that HIV-positive people taking these treatments are at a lower risk of developing thrombocytopenia.
Because most HIV-positive people—whether or not they are taking HIV treatment—have their blood tested regularly for abnormalities like thrombocytopenia, it's possible to treat the thrombocytopenia before it can cause bleeding disorders.
Are there any experimental treatments?
If you would like to find out if you are eligible for any clinical trials that include new therapies for the treatment or prevention of thrombocytopenia, visit ClinicalTrials.gov, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email email@example.com.
Last Revised: January 18, 2016