Blood Clot Test

Scientists at the Massachusetts Institute of Technology (MIT) are well on their way to making a screening test for life-threatening blood clots that's as simple as an at-home pregnancy test.

The test they've designed uses nanoparticles to sense thrombin, a key enzyme in blood clots. The test would allow doctors to better monitor patients who have a high risk of blood clots, said Dr. Sangeeta Bhatia, lead study author and a member of MIT's Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science.

According to the Centers for Disease Control, 60,000 to 100,000 Americans die each year from deep vein thrombosis and pulmonary embolism, two conditions caused by blood clots. 

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Blood clot formation involves a cascade of protein reactions. In order to convert fibrinogen to fibrin protein (which seals wounds), an enzyme known as thrombin helps complete the process. One currently used blood clot test—the D-dimer test—evaluates the blood for fibrin byproducts, but it fails to find the initial formation of the clot and only suggests that the clot is being broken down.

Bhatia said existing blood tests often do not consistently detect clot formation. The new urine analysis provides a more accurate diagnosis.

Creating a Thrombin Sensor

Bhatia first reported on a similar technology her team developed last year that aids in colorectal cancer detection. After discovering that the technology would work for blood clots as well, she applied it to identifying thrombin.

Researchers injected mice with iron oxide nanoparticles coated with peptides that interact with thrombin. When the particles found thrombin, they cut the peptides and released fragments into the animal’s urine. The urine was then treated with antibodies that are specific to the peptide tags in the fragments. The number of tags in the urine was proportional to the level of clotting in the mice’s lungs.

Benefits of a Rapid Blood Clot Test

Gabe Kwong, who worked on the research, said it may take a few years for the product become available, as it has to go through the Food and Drug Administration approval process. Next year, MIT will launch a company to commercialize the technology, he said. 

Bhatia said the test could be used to screen patients who have symptoms indicative of a blood clot. This would let doctors move quickly to treat them. It may also be used for patients who spend a lot of time in bed after a surgery, when doctors actively screen for blood clots.

Bhatia is working on a urine dipstick version of the test that patients could bring home with them and use to monitor themselves for clots.

“If a patient is at risk for thrombosis, you could send them home with a 10-pack of these sticks and say, ‘Pee on this every other day and call me if it turns blue,’” she said in a press release.

“Although obviously it is too early to tell for certain, this noninvasive test may significantly decrease the number of people who die or suffer serious effects from blood clots,” said Dr. Charlie Seltzer, a Philadelphia-based physician who was not involved in Bhatia's research.

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“By identifying people at high risk for clots, not only can injury and death be reduced, but so can the costs associated with testing a person with symptoms suspicious of a clot,” Seltzer added. Making what were once extensive hospital tests into outpatient ones, it could shift care from hospitals to doctor's offices, saving money for patients and the healthcare system.

Dr. Andre Berger, M.D., who founded the Rejuvalife Vitality Institute in Beverly Hills, Calif., is equally excited about the development.

“Once widely available as a commercially useful test, it will contribute to saving thousands of lives annually through earlier preventative intervention,” Berger said.