Encyclopedia of Health and Medicine

thrombocytopenia 171
phate and the CHEMOTHERAPY agents hydroxyurea
and anagrelide. Some people benefit from platelet
apheresis, a form of HEMAPHERESIS that removes
platelets from the blood and returns all other
blood components to the person. The doctor will
closely monitor the complete blood count (CBC)
as well as platelet function and coagulation during
treatment, usually with weekly blood tests.
Primary thrombocythemia is a chronic condition
that requires ongoing treatment. Many people
will remain relatively symptom-free once
treatment stabilizes platelet production. The condition
takes a more serious course in some people
who may experience worsening symptoms,
notably hemorrhage. Rarely, primary thrombocythemia
evolves into chronic myeloid LEUKEMIA
(CML), a cancer of the bone marrow.
Risk Factors and Preventive Measures
Because doctors do not know what causes primary
thrombocythemia, risk factors remain unknown
and there are no known preventive measures.
Early diagnosis and appropriate treatment offer
the most optimal prognosis (outlook) to minimize
the level to which the condition affects QUALITY OF
LIFE.
See also POLYCYTHEMIA VERA; THROMBOCYTOPENIA.
thrombocytopenia A disorder of the BLOOD in
which the blood contains too few platelets (also
called thrombocytes), the cells active in COAGULA-
TION (clotting). Thrombocytopenia, also called
thrombopenia, is a secondary condition that
develops as a consequence of prolonged bleeding,
aplastic ANEMIA, blood disorders such as THROMBO-
CYTHEMIA, and cancers affecting the BONE MARROW.
POTENTIAL CAUSES OF THROMBOCYTOPENIA
acute idiopathic thrombopenia ANTIDIABETIC MEDICATIONS
purpura
aplastic ANEMIA
AUTOIMMUNE THROMBOCYTOPENIA BLOOD TRANSFUSION reaction
chronic ALCOHOL consumption chronic idiopathic
CIRRHOSIS
thrombopenia purpura
GASTROINTESTINAL BLEEDING heparin
HIV/AIDS
LEUKEMIA
MYELOFIBROSIS
PLATELET dysfunction
quinidine
rifampin
SEPTICEMIA
sulfa ANTIBIOTIC MEDICATIONS
Certain medications may also cause thrombocytopenia
as an undesired SIDE EFFECT. Thrombocytopenia
may occur when the bone marrow cannot
produce enough platelets or when the SPLEEN and
LIVER remove too many platelets from the blood.
Symptoms and Diagnostic Path
The characteristic sign of thrombocytopenia,
regardless of its underlying cause, is excessive
superficial bleeding. Symptoms include
• PETECHIAE, pinpoint hemorrhages beneath the
surface of the SKIN that have the appearance of
a RASH
• ECCHYMOSIS, a pattern of easy and excessive
bruising with minor bumps and scrapes
• unprovoked bleeding from the nose (EPISTAXIS),
gums, URETHRA, and other mucous tissues
• blood in the urine, stool, or vomit
• excessive bleeding with dental procedures or
surgery
• signs of intracranial bleeding (bleeding within
the skull)
A blood test that shows the low PLATELET count
with normal counts and appearance of other
blood cells is fairly conclusive of the diagnosis,
especially when an underlying condition known
to cause thrombocytopenia also is present. The
doctor may choose to do a bone marrow biopsy.
Because thrombocytopenia can be an early indication
of HIV INFECTION, the doctor is also likely to do
an HIV antibodies test to determine whether HIV
infection is present.
Treatment Options and Outlook
Treatment depends on the underlying condition.
Sometimes platelet transfusions are necessary to
provide enough platelets for proper coagulation.
Thrombocytopenia is not usually a life-threatening
condition and typically resolves when the
underlying condition improves.
Risk Factors and Preventive Measures
The primary risk factors for thrombocytopenia are
the conditions that result in its development.
Avoiding these factors, such as alcohol consumption
or a medication that is causing thrombocytopenia
as a side effect, or treating the condition