Immune thrombocytopenia: when the platelet count falls

Platelets are the small blood cells that start a clot. In immune thrombocytopenia (ITP) the immune system produces antibodies against them, so they are destroyed faster than the bone marrow can replace them, and their production is reduced as well.

Many adults with ITP have few or no symptoms. Others notice easy bruising, tiny red spots on the skin called petechiae, nosebleeds, bleeding gums or heavy periods.

Ruling Out Other Causes

ITP is a diagnosis of exclusion. A low platelet count can come from medication, infections such as hepatitis C, HIV or Helicobacter pylori, liver disease, other autoimmune conditions or bone marrow disorders — and occasionally from clumping of platelets in the test tube.

A careful history, a blood smear examined under the microscope and targeted tests usually settle the question. A bone marrow examination is needed only when the picture is not typical.

When Treatment is Needed

Treatment is guided by bleeding and by the situations ahead, such as surgery or pregnancy, rather than by a platelet number alone. A patient with a modestly low count and no bleeding is often simply followed.

When treatment is needed, steroids are usually the first step, with intravenous immunoglobulin when a quick rise is required. For persistent or chronic ITP, thrombopoietin receptor agonists, rituximab and other options are available, and splenectomy is now considered much later than it once was.