For about 200,000 Americans with an autoimmune disease called idiopathic thrombocytopenic purpura, bruises are common. In this condition, the immune system attacks the blood platelets, cells that help maintain blood vessel structural integrity and are an important part of the process of clotting. The resultant low platelet count—as low as one-fortieth normal—makes patients more prone to hemorrhaging as well as spontaneous bruising. However, the condition is only fatal in a small number of severe cases.
It’s unclear what causes the immune system to respond to platelets as to infectious agents. In children, and to a lesser extent in adults as well, the condition is often triggered by a major viral infection, such as influenza or mumps. Adult idiopathic thrombocytopenic purpura generally strikes women of childbearing age, though it can affect anyone at any time, regardless of age or sex.
Aside from bruising, symptoms include:
- Excessive bleeding from cuts
- pinpoint reddish-purple spots from bleeding into the skin
- Bleeding from the gums after dental work, and occasionally at other times
- Heavy menstrual flow
- Bloody urine or stool
As with many autoimmune disorders, corticosteroids and immune suppressants are common treatment options. Other treatments include medications to boost platelet count and surgery to remove the spleen.