Saliva could replace blood, urine exams

By CHARLES Q. CHOI  |  Feb. 18, 2005 at 10:25 AM
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WASHINGTON, Feb. 18 (UPI) -- Saliva tests could begin replacing blood and urine tests within the next two years for everything from drugs to diseases, the benefits of which include ease of collection, not requiring needles and doable without the embarrassing need of having a doctor or drug tester watch the process.

"An employer doesn't have to greet an employee at the door with a urine cup," pharmacologist Edward Cone of ConeChem Research in Severna Park, Md., told United Press International.

Cone and colleagues presented their research at the American Association for Advancement of Science annual meeting.

For the last 15 years or so, scientists have tinkered with taking tests normally done with blood and urine and reconfiguring them for use with saliva, explained biochemist Daniel Malamud of the University of Pennsylvania in Philadelphia.

"Most people would rather have an oral test than the alternative," Malamud told UPI. "The best example is with the oral thermometer. Nobody wants to go back to the rectal thermometer."

The U.S. National Institutes of Health in Bethesda, Md., currently is funding 10 groups nationwide to advance saliva tests.

"What's in blood was known for decades to be found in saliva, but the level of (information) was magnitudes lower," oral health researcher David Wong of the University of California, Los Angeles, told UPI. "So the conventional technology could not be used until now, when sensitivity is much higher."

Malamud is working on a saliva test that can diagnose a variety of viral and bacterial diseases by detecting DNA from microbes such as HIV within an hour. This quick, simple diagnosis could help prevent unnecessary antibiotic use, which could lead to bacterial resistance. All that is needed is to move a tiny sponge around the mouth to collect less than a thousandth of a liter of fluid."

The research is about two years along, Malamud said. "Within the next year and a half or so, we plan to take multiple tests and combine them in a single device."

Biochemist Paul Denny of the University of Southern California in Los Angeles and colleagues found that different combinations of sugary proteins inside the mouth can reveal how genetically vulnerable a person can be to cavities. Using proteins called lectins that bind to these sugars, Denny and associates are developing a test that can reveal how at risk someone is to diseases of the teeth and gums.

"When applied to children, it's a prescription for prevention," Denny told UPI. "It's early information on what the future oral healthcare needs of that child will be."

Cone explained the U.S. Department of Health and Human Services is developing guidelines for adopting saliva tests in the workplace.

"The technology has evolved over the last decade to diagnose illicit drug use -- it's as accurate as urine testing," Cone said. In terms of fooling an oral drug test, "oral tests are primarily for drugs originating in the blood that can't just wash out of the blood. We've tried a number of mouthwashes, toothpastes. I'm not putting it past drug users for finding something, but so far we haven't found anything."

Police in Europe now routinely use the technique when stopping drivers and a number of private workplaces in the United States have begun using saliva tests as well. Saliva tests for steroid use or the presence of HIV -- the organism that causes AIDS -- also exist right now, Malamud said.

Wong's group and others currently are working to see which proteins are found in the saliva of normal people.

"If we could catalog all the proteins in saliva into a Periodic Table of sorts for healthy people, then you could compare it with the salivary proteome of the diabetic population or breast-cancer population, for example," Wong said. "We'll have a catalog of normal salivary proteins in about two years. He and colleagues recently reported in the December issue of the journal Clinical Cancer Research that RNA molecules in saliva can indicate whether a patient has contracted cancer of the head or neck.

Denny hopes saliva exams could move from testing for sickness to testing wellness -- for instance, examining the level of nutrients in a person's body.

"A wellness test could be done much more frequently and less expensively, and help maintain some concept of when the body's doing things right, rather than when it's doing things wrong," Denny said.

"A good side effect of prevention is lower medical costs," Wong added.


Charles Choi covers research and technology for UPI Science News. E-mail:

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