Blood thinners necessary to combat lung clots

DEAR DR. ROACH » I have a friend whose 50-year-old son is healthy except for having had his spleen removed in his 20s after an auto accident. Recently, he was diagnosed with blood clots in his lungs. He has had extensive tests, but none of his doctors could tell him why he was getting these clots. He was told he might have to stay on blood thinners for the rest of his life.

— W.B.H.

DEAR READER » Blood clots in the lungs, called pulmonary emboli, most often occur in people who have known risk for them.

There are many risk factors. Among the 20 or so known genetic risk factors, the most common include the factor V Leiden mutation, prothrombin gene mutations and deficiencies in protein C, protein S and antithrombin. These would be some of the many tests your friend’s son had.

Not all risks factors are genetic. Deep blood clots can come from prolonged immobility, surgery, infection and cancer. Some medicines, such as estrogens, can increase blood clot risk. Sometimes, the blood clot is the first indication that one of these states exists. More of your friend’s son’s tests will have been looking for these conditions.

Removal of the spleen can be done as treatment for some blood disorders or as emergency treatment for rupture of the spleen, as it sounds like in his case. It is well known that spleen removal increases the risk of certain infections. It is less well known whether it increases the risk of blood clots, but an autopsy study found a 500% increase in fatal blood clots among those who had had a splenectomy compared with those who did not.

When a cause for the blood clot can be identified and removed, only a relatively short duration of anticoagulation may be necessary. However, if a cause can’t be identified or if is identified but can’t be treated, then lifelong anticoagulation may be necessary. Some experts will recommend lifelong anticoagulation for a single life-threatening event, such as a pulmonary embolism. As always, a balance must be struck between the risk of serious bleeding from anticoagulation and the benefit in reducing risk of another clot. Clinical experience and judgment are critical. An experienced hematologist is an excellent resource for an expert opinion.