Thu, 13 Sept. 2012 - 9:11 p.m. MT
Credit: ARA Staff - American Running Association
QUESTION:
A male client of mine, in his mid-40s, is a distance cyclist who has developed his second DVT in three years. Why would a young healthy male develop clots?
Alice Hill
Tampa, FL
ANSWER:
I discussed this issue with one of my co-workers, who is a specialist in blood clotting disorders and a fellow runner, and have incorporated his comments into my response.
There are several reasons why people form DVTs. There are a number of clinical entities associated with increased risk of forming a blood clot, including recent surgery, prolonged immobilization such as a long airplane flight, certain medications, and the presence of other diseases such as some types of cancer or kidney disease. In the vast majority of cases these entities associated with increased risk of clotting are readily
apparent and provide an explanation as to why the DVT formed.
There is some controversy as to whether severe and prolonged exercise by itself can
be associated with DVT. Some studies suggest that acute severe exercise increases the tendency for blood clotting, although chronic exercise training may lower this risk. There are anecdotal reports of marathon runners being diagnosed with a blood clot shortly after running a marathon, and some authors have speculated that dehydration may play a role, but these observations remain primarily anecdotal.
Some otherwise healthy adults who form DVT may have an abnormal antibody in
their bloodstream that predisposes toward clotting (e.g., the lupus
anticoagulant / antiphospholipid antibody). Some may have a deficiency or abnormality of a protein that participates in the body's clotting/clot-inhibiting systems. These protein deficiencies/abnormalities are genetic and include entities such as antithrombin deficiency, protein C deficiency, protein S deficiency, Factor V Leiden mutation, prothrombin 20210, and dysfibrinogenemia, among others.
There are laboratory tests to screen for these genetic abnormalities. These
tests are expensive. Performing these tests in your client's situation
could be helpful for addressing why he has developed DVTs but would
unlikely lead to later treatment recommendations. Most authorities would argue
that since your client has had a second DVT, he should be treated with
life-long Coumadin therapy (unless there is a contraindication), regardless
of what the tests indicate. Since the protein deficiencies/abnormalities
are genetic, the presence of one of these disorders does have implications
for passing on this abnormality to one's offspring, and testing could be
important for this reason.
Todd Miller
Rochester, MN
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(RUNNING & FITNEWS® March / April 2009 • Volume 27, Number 2)