Ask Dr. Stephan Moll

These questions have been submitted by folks on the mailing list and answered by Dr. Moll, Director of the Thrombophilia Program at the Carolina Cardiovascular Biology Center, Department of Medicine, Division of Hematology-Oncology, UNC Chapel Hill (North Carolina, USA). Why am I doing this?

58. Low platelets and clotting

Q: "I was diagnosed with Factor V Leiden last year after developing a blood clot in my leg. Yesterday my 17-year-old daughter was diagnosed with a blood clot in her leg. The strange part is that 3 years ago she was diagnosed with chronic ITP [Idiopathic Thrombocytopenia Purpura], and has been treated with steroids ever since. Doesn't this seem conflicting?? At present, her platelet count is at 30 thousand, but they have started Lovenox® injections."

A: ITP is a disorder in which platelets are destroyed by the body and therefore decrease. It is an autoimmune disease, i.e. a disturbance of the immune system: the patient's immune system thinks it needs to get rid of platelets and produces antibodies against them that destroy them. Low platelets typically lead to a bleeding tendency and not a clotting tendency. However, ITP can be associated with the immune disorder antiphospholipid-antibody-syndrome (also see Q/A 21, Q/A 54, Q/A 56). Patients with this disorder may have a clotting tendency in spite of low platelets.

The disorders that cause low platelets and clotting at the same time are:

1. Antiphospholipid antibody syndrome;
2. TTP (= thrombotic thrombocytopenic purpura; highly unlikely in the above patient, since it is typically an acute disease and does not present over a three year duration)
3. HIT (= heparin induced thrombocytopenia; not likely in the above patient, since she was probably not on heparin at the time of diagnosis of ITP or at the time when she presented with the leg clot);
4. Malignant tumors (unlikely in a young patient);
5. DIC (= disseminated intravascular coagulation; highly unlikely in a non-hospitalized patient without any serious underlying disease);
6. Presence of a strong underlying inherited thrombophilia and coincidental occurrence of ITP (= Immune Thrombocytopenia Purpura).

If in the patient with a deep vein thrombosis anticoagulation is stopped or can not be given because of low platelets, one should consider an inferior vena cava filter (transient or permanent IVC filter).

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