Blood Test Determines Radiation Exposure Levels

Patients can then be handled according to whether they received no exposure to radiation, an intermediate level of exposure that may respond to medical therapies, or an inevitably lethal dose.

High doses of radiation can damage or wipe out a person's blood and immune systems, leading in some cases to bone marrow failure accompanied by infections, bleeding, and a heightened lifetime risk of cancer. The symptoms of radiation exposure can take days or weeks to develop, and therefore, it could be difficult to identify individuals truly exposed without a practical test to make this distinction. Current treatments for radiation exposure aim to bolster the blood and immune systems before the damage becomes too severe.

In the event of a nuclear or radiologic catastrophe, thousands of people would be exposed to radiation, with no way of quickly determining how much of the deadly substance has seeped inside their bodies. Scientists at Duke University Medical Center (Durham, NC, USA) have developed a new blood test to rapidly detect levels of radiation exposure so that potentially life-saving treatments could be administered to the people who need them most.

There appears to be a critical window of 48 to 72 hours for administering treatments aimed at halting the devastating effects of radiation, according to senior study investigator John Chute, M.D., an associate professor of medicine in the Duke Adult Bone Marrow and Stem Cell Transplant Program. But existing tests for measuring radiation exposure take several days and are not practical for testing large numbers of patients at once.

If a terrorist attack involving radioactive material were to occur, hospitals might be overrun with people seeking treatment, many of whom have actually been exposed and many of whom are simply panicked, Prof. Chute said. We have to be able to efficiently screen a large number of people for radiation exposure in order to respond effectively to a mass casualty event.

The scientists subjected mice to low, intermediate, and high doses of radiation and looked for the impact of each dose on specific genes in the blood. They found that each dose resulted in distinct profiles, or signatures, representing 75 to 100 genes that could be used to predict the degree of exposure.

They also analyzed blood from human patients receiving bone marrow transplants that were treated with high doses of radiation prior to transplant and found specific gene profiles that distinguished the individuals that were exposed to radiation from those that were not with an accuracy of 90%.

The scientists published their findings in the April 3, 2007, issue of the journal Public Library of Science (PLoS) Medicine.


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