Australian researchers have devised a test that screens carbon dioxide in exhaled breath to check for liver-related damaged caused by hepatitis and other chronic diseases, the Australian Associated Press reports. Hepatitis A and B viruses can be transmitted through sexual contact, and the Gay and Lesbian Medical Association urges all sexually active gay and bisexual men to be vaccinated against the diseases. Hepatitis C also may be passed through certain sexual activities and has emerged as a major cause of death among adults also coinfected with HIV. Hepatitis can cause severe liver damage, including liver scarring, cancer, and death.
"Essentially, when we do a liver biopsy, one of the main questions is to work out whether they have developed cirrhosis or advanced fibrosis, and the only way we can do that at the moment is through a biopsy," lead researcher Gordon Park told the AAP. "We've found that our breath test, which is a noninvasive method of looking at the liver, can detect the amount of scarring or fibrosis in the liver quite sensitively." Liver biopsies are typically very painful for patients, the researchers added, and can cause internal bleeding and damage to other organs.
The breath test is based on the liver's ability to metabolize caffeine. Patients drink fluids that contain carbon-tagged caffeine, and as the liver processes the caffeine the carbon-tag is metabolized by the liver and enters the bloodstream. Eventually, the carbon is incorporated into carbon dioxide and exhaled from the lungs. By examining the levels of the carbon tag in the exhaled breath, the researchers can determine if the liver is properly processing caffeine of if caffeine metabolization is impaired due to liver damage.
The test is currently being evaluated at hospitals in Sydney but could be more widely available by the end of 2005. Each breath test costs about $37.