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Genetically Engineered Thyroid Test

By Sean Henahan, Access Excellence 

Baltimore, MD (9/30/97)-  A genetically engineered form of human thyroid-stimulating hormone offers an effective and safer alternative to the cnventional test now used, report researchers at Johns Hopkins University. 

The research invovled recombinant human thyroid-stimulating hormone (rhTSH), a synthetic form of thyroid-stimulating hormone, the hormone produced in the pituitary gland that stimulates the thyroid to release an essential hormone for regulating metabolism. Ordinarily, patients receiving chemotherapy for thyroid cancer need to stop taking their thyroid medications for TSH testing. This can cause a host of problems including fatigue, depression and weight gain. The new study showed that rhTSH facilitated accurate testing for recurrent cancer while patients stayed on their usual thyroid hormone suppression drugs. 

"This could revolutionize the way we manage the health care of  patients with thyroid cancer," says Paul W. Ladenson, M.D., director of endocrinology and metabolism at Johns Hopkins. "In most patients, the test quality with the synthetic compound is the same or better than with traditional hormone withdrawal and with a markedly higher quality of life for patients." 

The research represents a culmination of  nearly ten years of research. In 1988, members fo the research team discovered the gene for human thyroid-stimulating hormone. This was the key step needed for the development of the synthetic TSH and the new test that followed. 

In the current study, the researchers evaluated 127 people who had part or all of their thyroid gland removed because of cancer. Each patient had a test called a radioiodine scan to look for  recurrence of cancer. The first scan was done while patients took both their thyroid hormone suppression drug and rhTSH. The second scan was done the traditional way, with patients taken  off hormone suppression medication temporarily so the thyroid gland was reactivated to absorb the radioiodine on its own. 

The scans using the artificial compound turned out to be as good or better than the traditional method in 109 patients, or 86 percent of the study group. Of these, 106 had equal scans  and three had better scans. 

The results also indicated that the patients had a better quality of life when given the artificial compound coupled with their medication than when they were taken off medication. The quality of life score measured the severity of hypothyroid symptoms, including depression, weight gain, fatigue, muscle weakness, cramps and dry skin. 

Traditional post-operative treatment of thyroid cancer patients includes a long period of taking medication to suppress production of thyroid-stimulating hormone, which may fuel tumor growth, and periodic radioiodine scans to make sure the cancer has not returned. 

Going on and off hormone-suppression therapy typically causes unpleasant symptoms that put stress on the body, including strain on the heart, as patients' thyroid hormone level falls. 

"It is gratifying to see these results. We anticipate that patients will no longer have to endure the debilitating side effects of hypothyroidism in order to have sensitive testing to detect thyroid cancer," noted Bruce D. Weintraub, M.D., of the University of Maryland Medical Center. 

The study was published in the Sept. 25, 1997 issue of The New England Journal of Medicine. 

Related information on the Internet
rhTSH Backgrounder
Thyroid Home Page
Thyroid Cancer 

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