Thrombocytopenia is a condition, where the platelet count drops below the normal level. The normal range of platelets, for every microlitre of blood, is 150 000 to 450 000. Hence if the number of platelets, per microlitre of blood, drops below 150 000, the individual is affected with Thrombocytopenia. When the platelet count falls below 50 000 or less, there is a risk of mild bleeding. When the platelet count falls below 20 000, enhanced bleeding occurs since platelets are necessary for blood clotting. Thrombocytopenia can last for either a few days or persist for years. Thrombocytopenia in the brain may be fatal, if there is bleeding. However, the general prognosis for thrombocytopenia is good, where the condition can be treated with medications or with transfusions of blood or platelets. Diagnosis of thrombocytopenia can be made with a simple blood test called the complete blood count.
Causes of Thrombocytopenia
Thrombocytopenia is a result of low blood platelet count, which can be caused due to medications, or other disease conditions.
A decrease in the blood platelet count can be due to the following factors:
1. Low platelet count generated by insufficient platelet production in the bone marrow.
2. Low platelet count due to breakdown of platelets in the blood stream.
3. Low platelet count in the blood since the spleen stores an excess amount of platelets.
4. Low platelet count due to breakdown of platelets in the liver or spleen.
On a larger perspective, reduction in platelets is either due to reduced production of platelets or due to destruction of the existing platelets.
Different conditions that cause the destruction of new platelets are as follows-
1. Prolonged alcohol consumption.
2. Effect of chemotherapy medications.
3. Viral infections (HIV, chickenpox, hepatitis C).
4. Deficiencies of Vitamin B12 and folate
5. Lymphoma or leukemia.
6. Bone marrow treated with radiation.
Destruction of existing platelets can be due to the following factors-
1. Bypass surgery of the heart.
2. Idiopathic thrombocytopenia purpura.
3. Pregnant women with preeclampsia.
4. Thrombotic thrombocytopenia purpura.
5. Side effects of medications (heart drugs, stomach drugs, non-steroidal anti-inflammatory drugs, anti-epilepsy drugs).
6. Autoimmune conditions (rheumatoid arthritis, lupus erythematosis)
Thrombocytopenia also develops in 5% of normal pregnant women, in patients receiving excessive blood transfusions, and in enlarged spleens containing nearly 90% of blood platelets. Newborn infants sometimes develop neonatal thrombocytopenia when admitted in intensive care units of hospitals.
Thrombocytopenia with Absent Radii (TAR), is a rare, inherited disorder of the blood and skeletal system. Bleeding is observed in infancy with disorders in the upper limbs. Low levels of a protein, observed in certain families, causes TAR.
3. Albers CA et al. Compound inheritance of a low-frequency regulatory SNP and a rare null mutation in exon-junction complex subunit RBM8A causes TAR syndrome. Nat Genet. February 2012;44(4):435-439.
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