Patient Information Resource:
Benign Hematologic (Blood) DisordersA collaborative project of the Arizona Telemedicine Program, the Arizona Health Sciences Library and the Arizona Cancer Center.
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Thrombocytopenia
A. What Is Thrombocytopenia?
Thrombocytopenia is a bleeding disorder in which the blood contains lower than normal levels of functional platelets. It can be a result of many diseases and is the most common cause of bleeding in cancer patients. Platelet levels may fall due to insufficient bone marrow production, increased consumption of platelets, or abnormal platelet removal from the blood by the spleen.
Platelets are an integral part of the blood’s clotting mechanism, enabling the body to control bleeding at the site of injury. When a wound occurs, several changes take place to minimize blood loss. First, the blood vessel slows the flow of blood past the wound site. Next, platelets collect at the wound site to form a plug, which remains for two to five hours. This plug is then replaced by a coagulation (clotting) protein, fibrin, that forms a clot to block the wound site until it has healed.
Platelets are produced in the bone marrow and are removed from the blood by the spleen. Therefore, these two organs work together to regulate platelet levels in the blood. Because platelets are fragile cells, they are easily damaged in many disorders and are especially vulnerable in bone marrow diseases. In cancer patients, thrombocytopenia may result from the presence of the tumor or may occur in response to the chemotherapy or radiation used in treatment.
B. Causes
Thrombocytopenia may be due to insufficient platelet production or to platelet destruction in the blood or spleen. Platelet production in the bone marrow may be suppressed by leukemia, aplastic anemia, burns, cancer chemotherapy, exposure to radiation used in cancer treatment, HIV virus, and nutritional deficiencies (see Vitamin B12 Deficiency and Folic Acid Deficiency). In addition, myeloproliferative disorders such as myelofibrosis with myeloid metaplasia may lead to lowered platelet levels (see Myeloproliferative Disorders). Outside of the marrow, platelets can be destroyed by heat stroke, prosthetic heart valves, infections, large-bore intravenous lines (often used in ICU), and excessive platelet removal by the spleen.
Substances that interfere with platelet production or function include: alcohol, histamine-2 blocking agents such as cimetidine (Tagamet) and ranitidine (Zantac), hormones, thiazides such as Diucardin [hydroflumethiazide] and Diuril [chlorothiazide], heparin, and sulfa drugs such as Bactrim.
In addition, a patient’s own immune system may destroy the platelets in the blood. Patients with idiopathic thrombocytopenia purpura, thrombotic thrombocytopenia purpura, mononucleosis, and some viral infections may suffer autoimmune platelet destruction. Some vaccinations may also result in autoimmune thrombocytopenia.
C. Signs and Symptoms
Because thrombocytopenia causes excess bleeding, its symptoms may be readily notable. On the skin, petechiae (small purplish-red spots), rashes, and easy bruisability may appear. These symptoms may be provoked by minor injury or pressure. In addition, the patient may note bleeding from wounds or body cavities. If the platelet count is extremely low (< 20,000/mm3), spontaneous bleeding results. If thrombocytopenia is due to spleen activity, both spleen and liver may be enlarged and tender to the touch. The inability to clot may also lead to blood in the stool, urine, vomit, or sputum. Some patients with thrombocytopenia are also anemic. They may feel fatigued or have an elevated heart rate. For other symptoms of anemia, please see Anemia.
D. Diagnosis
The diagnosis of thrombocytopenia is based on patient history, physical examination for symptoms, and laboratory testing. Although there are several bleeding disorders, a patient is suspected to have thrombocytopenia if bleeding occurs immediately after an injury, when platelets would normally be responsible for clotting.
E. Treatment
The first step in treating thrombocytopenia is to address (if possible) the underlying cause of the deficiency. In addition, if sufficient blood loss has occurred, red blood cell or platelet transfusions may be needed. Platelet growth factor may also be used to stimulate platelet production in the marrow. In addition, patients should avoid drugs, especially anti-platelet drugs like aspirin and Advil.
GENERAL DISCLAIMER: This web site and its contents are designed for educational purposes only. This web site does not render medical advice or professional services. The information provided should not be used for diagnosing or treating a health problem or disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.
Updated: October 30, 2000