Entries in Blood Tests (2)


Skin Pricks, Blood Tests Not as Reliable as Food in Testing for Allergies

Cliff Moore/Getty Images(ELK GROVE VILLAGE, Ill.) -- A simple skin-prick or blood test has confirmed many people's suspicions that they have certain food or seasonal allergies, but a study published Monday in the journal Pediatrics suggests that allergy diagnoses should not be made solely on results from such tests.

Skin or blood tests remain the only method used to diagnosis allergies for some, the researchers wrote. And in some cases, patients who never exhibited symptoms are still tested for allergies.

About 3 percent of adults and 6 percent of young children have at least one food allergy, according to the National Institutes of Health.

Eating small doses of the suspected allergy culprit while under medical supervision -- called a food challenge -- is the gold standard for diagnosing food allergies, according to the researchers. The test directly measures whether a person develops an allergic reaction.

Tests like the skin prick, which puts a small amount of the allergen on the end of a needle while it pokes the skin, or a blood test measure antibodies that build up in the blood or around the prick site when a person is exposed to the allergen. But these tests do not measure the type of allergic reaction a person will get or how severe the reaction will be.

Previous research suggests that 8 percent of children will test positive for allergies on a skin or blood test, but only 1 percent will develop physical symptoms of an allergy.

Additional tests like a skin prick or blood test should only accompany the more reliable food challenge, the authors said.

Copyright 2011 ABC News Radio


PSA Tests for Prostate Cancer: More Harm than Good?

Comstock/Thinkstock(WASHINGTON) -- The U.S. Preventive Services Task Force publicized Friday its recommendation that healthy men should no longer receive PSA blood tests for prostate cancer as part of routine cancer screening. The government panel’s recommendation supports the growing notion that the blood tests often do more harm than good.

The blood test is designed to detect higher than normal levels of prostate-specific antigen, or PSA, in the blood. A high level can signal prostate cancer, but it can also indicate more benign conditions. A positive PSA test can lead to invasive biopsies, which come along with their own raft of considerations, including impotence and incontinence.

Science appears to support the recommendation. The USPSTF outlined in a report published early in the Annals of Internal Medicine that an analysis of the five largest studies on PSA testing suggested that the benefits of such tests appear minimal, while the downsides are considerable.

Still, some doctors worry that the recommendation could add to public confusion over the true benefits of screening tests that, in the past, they may have been encouraged to seek out. And it’s an issue that is not limited to prostate cancer screening; the USPSTF in 2009 recommended against annual mammograms for women age 40 to 49 because, they said, the benefits of testing do not outweigh the harms.

“The public often feels frustrated with the seeming ‘mixed messages’ that come from the medical establishment,” Dr. Jehan El-Bayoumi, residency director at George Washington University, told ABC News. “One minute we’re telling people to get screened, the next minute we’re telling people that it doesn’t make a difference. And so, no wonder the public is confused.”

Indeed, there is currently no overarching consensus on PSA testing. Dr. Pat Walsh of Johns Hopkins University, a world-renowned urologist and pioneer in nerve-sparing prostate surgery, called the updated recommendation “a shame.”

“This decision ignores the fact that there has been a 40 percent reduction in prostate cancer deaths over the past 10 years since PSA testing has been in place,” Walsh said. “The USPSTF ignores this because it relies only on randomized trials, and there are a number that have too short a follow-up and other serious deficiencies.”

Dr. Leonard Gomella, chairman of urology at Thomas Jefferson University, called the decision an “appalling affront to all men who will die from prostate cancer.” Dr. William Catalona, director of the Clinical Prostate Cancer Program at Northwestern Memorial Hospital, said, “The extent to which PSA screening causes over diagnosis and overtreatment is exaggerated.”

“I have to wonder whether economics are playing a role in the decision of the Task Force,” said Dr. Jerome Richie, chief of urology at Brigham and Women’s Hospital.

Several nonurologists, however, applauded the USPSTF’s move.

“I think this recommendation is long overdue,” said Dr. Thomas Schwenk, professor of family medicine at the University of Michigan.

“This advisory mirrors my advice to patients over the last 10 years,” said Dr. William Golden, director of general internal medicine at the University of Arkansas. “I have long believed that prostate cancer had a cure worse than the disease.”

“People have a need to believe, a need to feel that we have some power over this terrible disease,” said Dr. Lee Green of the University of Michigan. “Admitting the truth, that PSA screening doesn’t really save lives, is unacceptable because it takes that away. It’s scientifically correct, and will provoke a firestorm.”

Only time will tell whether the new USPSTF recommendation will be accepted by the medical community at large.

Copyright 2011 ABC News Radio

ABC News Radio