Thrombocytopenia (low platelet count)

Definition

Thrombocytopenia refers to the low platelet count in the blood. These platelets (thrombocytes) are colorless blood cells responsible for the formation of blood clots that prevent bleeding in the case of blood vessel cuts.

Different disorders such as leukemia or malfunction of the immune system or a medication side effect may lead to thrombocytopenia. Complications may range from none to severe bleeding.

Treatment of thrombocytopenia is carried out by treating the main cause. Medications or surgery can help in chronic cases. Sometimes, patients may need blood or platelet transfusion in case their bleeding is severe.

Emergency medical care is required when a large scale, heavy bleeding occurs.

Causes:

Bone marrow continuously produces platelets, each having a lifespan of approximately 10 days, and their count in the blood ranges from 150 to 450 thousand per cubic millimeter.

The risk of bleeding is adversely proportional to the platelet count, especially when it drops below 10,000 platelets per cubic millimeter, which though rare, permits internal bleeding even in the absence of an injury.

Thrombocytopenia is caused by one of the reasons listed below:

Reduced production of platelets:
The function of bone marrow in producing platelets is affected by various conditions such as leukemia and some types of anemia that may result in reduced production of platelets, along with viral infections like HIV, cancer, chemotherapy drugs and alcohol abuse.

Increased breakdown of platelets:
This may be caused by certain conditions that result in a shortage of platelets in the bloodstream due to the body using up or destroying platelets more rapidly than they are produced, such as:

Pregnancy:
Mild thrombocytopenia may be caused by pregnancy.

Idiopathic thrombocytopenic purpura (ITP):
In this condition, platelets are wrongfully identified as threats by the immune system and attacked by the antibodies that it produces.

Other autoimmune diseases:
In this case, a malfunction of the immune system causes the destruction of platelets, such as in lupus or rheumatoid arthritis.

Blood poisoning:
This condition may lead to the destruction of platelets; it is caused by severe bacterial infections (bacteremia).

Thrombotic thrombocytopenic purpura (TTP):
This condition is characterized by the sudden formation of small blood clots throughout the body, which consume a large quantity of platelets. Its cause is generally unknown but sometimes occurs due to genetic deficiencies. It can also be accompanied by a chronic disease or infection. Though rare, but it is a life-threatening condition.

Hemolytic uremic syndrome:
This condition also causes a rapid decrease in the platelet count as a result of their destruction, along with red blood cells and an eventual disruption of kidney function. Bacterial infections sometimes accompany this disease such as Escherichia coli (E. coli) infection from eating raw or undercooked meat.

The immune system sometimes malfunctions and starts destroying platelets as a result of certain medications, initiating a thrombocytopenic reaction. These medications include quinine, quinidine, heparin, some oral diabetes drugs, gold salts, rifampin, and sulfa-containing antibiotics.

Excessive blood clotting may occur instead of bleeding by heparin-induced thrombocytopenia; this increases the risk of clot formation in the legs or their transport to the lungs which is a potentially fatal condition.

TRAPPED PLATELETS IN THE SPLEEN:
In some cases an enlarged spleen may contain a considerable amount of platelets thus decreasing their count in the blood stream.

Complications

Complications:

Mild cases of thrombocytopenia have no permanent effects, while severe cases may cause bleedings in the digestive tract or the brain, which is rare but fatal.

The conditions that cause thrombocytopenia are usually the ones that cause complications. For instance, if the kidney damage is permanent in the kidney failure that accompanies hemolytic uremic syndrome, the patient may need lifelong treatment.

Treatments:

In some cases of thrombocytopenia, the bone marrow increases its activity to make up for the destroyed platelets until the underlying cause is removed, so not all cases of thrombocytopenia need treatment, especially in children. Newly produced platelets are more active in clotting, thus the child may not need any treatment or have bleeding problems even if the overall platelet count is low. Mild Thrombocytopenia in pregnancy usually improves shortly after delivery.

If thrombocytopenia is diagnosed, a physician’s efforts should be directed to treat the initial cause, whether it is the side effect of a medication or another illness. Several options are available to treat thrombocytopenia, including:

Medications:
In the case of idiopathic thrombocytopenic purpura, medications like corticosteroids are administered to prevent the antibodies from attacking the platelets. When a rapid boost of platelet count is necessary, intravenous immunoglobulin may be administered. In some more severe cases, medications are used to suppress the immune system decreasing the rate of antibody production. Examples of these drugs are cyclophosphamide and azathioprine.

Surgery:
A splenectomy, which is the surgical removal of the spleen, is performed to treat chronic idiopathic thrombocytopenic purpura that is not responding to corticosteroids, thus reducing its sign and symptoms.

Blood transfusions and plasma exchange:
Blood transfusions of packed red blood cells is carried out in cases of severe bleeding. In cases of chemotherapy or cancer, severe thrombocytopenia is treated with platelet concentrates.

Emergency treatment with plasma exchange therapy or therapeutic plasmapheresis is required in the case of thrombotic thrombocytopenic purpura. On the other hand, kidney dialysis along with red blood cell and platelet transfusions may be necessary in the case of hemolytic uremic syndrome.