Idiopathic thrombocytopenic purpura (ITP)

Our blood contains three types of cells- red blood cells, necessary for carrying oxygen to all the parts of body, white blood cells necessary for fighting against infections and platelets also known as thrombocytes which are required for the normal clotting of the blood.

Thrombocytopenia is a condition in which the platelets are decreased in the blood.

The word purpura refers to reddish blue spots which appear under the skin as a result of small hemorrhages. Though there are many causes of thrombocytopenic purpura the most common in children is Idiopathic Thrombocytopenic purpura.

In this condition the platelets are destroyed by antibodies produced in the body usually after some infection through it is not known why some children produce antibodies against their own platelets. The condition is more common in females than in males and most frequently occurs between 2 and 5 years of age.

The disease occurs in two forms-acute and chronic. The acute form resolves within 6 months where as the chronic form lasts for more than 6 months.

The disease usually manifests as spontaneous bleeding into the skin. There may be bleeding from the nose. The hemorrhages appear as reddish blue spots. The child looks otherwise healthy.

Laboratory findings: The platelets are decreased in number to usually <50,000 per micro-liter. The normal count is 150,000-400,000 per micro-liter. White blood cells (leukocytes) are normal in number and morphology. There will be no significant anemia.

Bone marrow examination is not routinely performed but only if some atypical features are present. If done, it will be normal except for increased platelet precursors.

Complications

Severe bleeding can occur if the platelet count is very low. Intracranial hemorrhage is a dreaded complication but is likely only if the count is less than 10,000 per micro-liter.

Treatment

General-Injury should be prevented as for as possible. Child should not be given drugs like aspirin which can predispose to bleeding.

Mild disease may not require any specific treatment as the disease resolves by itself. The body compensates for the loss of platelets by producing more. The antibodies against platelets are removed by the body and ultimately the abnormal destruction of platelets stops.

But if a child has bleeding associated with low platelet count treatment is indicated. Prednisone is given in appropriate doses. The drug is tapered and stopped over a period of two weeks. Patient is regularly monitored till the platelet count returns to normal.

Intravenous immune globulin: This can be given in a dose of 1 gram per kg body weight of the child per day for 1 to 3 days if the patient is not responding to prednisone or there is severe bleeding. The response is usually prompt. The treatment is costly.

Anti D immune globulin: The intravenous preparation of anti D antibody can help in preventing abnormal destruction of platelets. The immune globulin has no direct action on the platelets. It coats the RBSs and the coated RBCs compete with the platelets at spleen where destruction takes place. Hence this can only be effective in a patient who is Rh positive and has a normal spleen.

Platelet transfusion: If there is significant bleeding platelets can be transfused. Platelets are separated using a special centrifuge.

Splenectomy: As platelets are destroyed in the spleen, splenectomy (removal of spleen) stops abnormal destruction of platelets and improves the platelet count. But splenectomy is associated with some complications and hence is not routinely performed. It is considered only if all other measures fail and significant thrombocytopenia persists for more than one year.

The risk of serious infections increases after splenectomy especially in young children. Hence is should preferably be postponed till the child completes at least five years of age. Pneumococcal and Hemophilus Influenza B vaccines should be administered two weeks prior to surgery. Some authorities recommend Miningococcal vaccine as well.

Prognosis

The overall prognosis is very good. Nearly 90 percent of children recover completely.

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