Successful Treatment Of Idiopathic Thrombocytopenic Purpura (ITP) With IVIG
Question: Two months ago, our five-year-old son developed a rash after a cold. Our doctor sent him to a paediatrician. Following some blood tests, we were told that his platelets were low. When he started developing bruises on his forehead, the doctors gave him immunoglobulin through an IV. He has since completely recovered. Some of our relatives told us that he should have more tests done because they knew someone who developed bruises from leukemia. Should we insist on more tests or referral to other specialists?
From your description, your son most likely had the condition called idiopathic thrombocytopenic purpura (ITP). This is a fairly common condition of the blood in children. Your paediatrician likely has had quite a bit of experience from his/her training.
As the word idiopathic implies that we still don’t understand fully the cause of this medical condition. It is classified into two types: acute and chronic.
Acute ITP happens in young children who are perfectly healthy. After a relatively mild viral infection, these children suddenly develop a red rash. On close examination, the rash doesn’t blanch with pressure on the skin. It is because the rash is actually due to small bleedings underneath the skin. These spots are called petechiae. Larger bruises, called purpura, can occur as a result of minimal trauma.
Other sources of bleeding include the nose, the mouth, and in the urine. Usually bleeding is not severe enough to reduce haemoglobin in the blood. However, the petechial and purpuric rash can be quite alarming to parents.
This bleeding is due to reduction in platelets in the blood. There are several types of cells in our blood. The red blood cells carry oxygen and remove carbon dioxide from tissues. The white blood cells help us to fight infections. The platelets are very small blood cells that help the blood to clot. If the number of platelets decreases, or if the platelets don’t work properly, our blood cannot clot in a normal way. Therefore it is easy for bleeding to occur underneath the skin, giving rise to petechiae and bruises. Any little cut can result in prolonged bleeding.
As I mentioned earlier, the exact mechanism of ITP is still unknown. It is speculated that some viral infections can trigger the body to produce antibodies that attack the platelets. When that happens, the platelets are destroyed faster than normal, leading to low platelets. Normal platelet count is over 150. When platelets drop to 20 to 30, symptoms of petechiae and bruises will occur.
Most of the time, platelets in this range wouldn’t cause serious problem, in spite of the alarming spots on the skin, and treatment is unnecessary. However, if platelets drop below 20, or if bruises occur on the head, there is a serious concern with haemorrhage inside the skull (this is called intracranial haemorrhage, or ICH).
Fortunately, ICH due to ITP is very uncommon. Over the past twenty years, only about 50 cases have been documented in North America. When it happens, however, there is a high risk of brain damage and death. That is why treatment is often recommended when platelet count drops to below 20.
Several treatments are available for ITP. Your son received intravenous immunoglobulin (also called IVIG). This is a very effective, although rather expensive medicine. The immunoglobulin is made from donors’ blood, but it is treated in such a way that all potential infectious germs have been eliminated. It increases platelets in the blood within one to two days, thereby reduce the risk of serious haemorrhage. Side effects are uncommon.
Another treatment available is steroids. Since ITP is due to production of abnormal antibodies against platelets, steroids can alter the immune system and increase platelet count. There are additional treatments that I will not discuss here.
Over 80% of children with acute ITP will recover completely, often without treatment. There used to be controversy whether more investigation is needed. Research has clearly shown that if the child has typical symptoms, totally normal red and white blood cells, and the platelets return to normal, there is no need for further investigation like the bone marrow test.
It is very true that patients with leukemia can have petechiae and bruises like ITP. However, almost all of them have other symptoms and signs that can distinguish them from ITP. These patients often have fever, lethargy, and recent weight loss. Physical examination can reveal enlarged liver, spleen, and lymph nodes. The most important feature is abnormal blood tests. Children with ITP have completely normal blood count except for low platelets. In leukemia, the red blood cells are usually low, and white blood cells are either too high or too low. Not infrequently, cancerous white blood cells can be seen in the blood when examined under microscope.
Your doctors have given your son the best treatment possible. If his platelet count has returned to normal after IVIG, he doesn’t need any more investigation. However, he should still be followed by your doctor with regular physical examination and possibly blood tests.
I should mention briefly here about chronic ITP for the sake of other readers. If the platelet count remains low for longer than 6 months, the person has chronic ITP. This condition is due to the body producing abnormal antibodies against its own platelets. This is similar to many other “auto-immune conditions,” where the body develops antibodies against different tissues and organs. Examples of these include thyroid conditions, diabetes in children, rheumatoid arthritis, and lupus, to name a few.
Treatment of chronic ITP is difficult, because the response to medicines like IVIG and steroids are often short-lived. There are several other newer medications available, which is beyond the scope of this discussion. Since damaged platelets are broken down by the spleen, removal of the spleen (splenectomy) can “cure” chronic ITP. However, the benefit of this surgery has to be balanced with the risk of life-threatening infection: spleen is an important organ that helps the body to fight infection.