Blood Test May Spot Serious Health Risks in Women
New biomarker reveals odds of heart disease, diabetes and breast cancer, study says
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Tuesday, October 9, 2012
The test, which measures levels of a substance called proneurotensin, may also spot an increased risk of early death, the researchers behind the study said.
"In women, but not in men, there were very strong relationships between high concentrations of proneurotensin in the blood and the risk of developing diabetes, cardiovascular disease and breast cancer," said the study's lead author, Dr. Olle Melander, professor of internal medicine at Lund University in Malmo, Sweden.
"Women with high levels of proneurotensin in the blood died significantly earlier than women with normal proneurotensin concentrations, and the excess mortality with high proneurotensin was primarily caused by cardiovascular diseases," added Melander.
Results of the study are published in the Oct. 10 issue of the Journal of the American Medical Association.
Proneurotensin is a precursor of neurotensin, a hormone produced in the brain and in the digestive system that is secreted during meals -- particularly high-fat meals. Neurotensin has a number of jobs in the body: It helps with food digestion, the regulation of body temperature and the sensation of pain, and is also involved in the regulation of appetite and feelings of fullness, Melander said.
In several recent studies, the hormone has also been linked to heart disease risk and to the growth of breast cancer tissue, said Melander.
But neurotensin levels are very difficult to measure. Proneurotensin, its precursor, however, is a stable indicator of the production and secretion of neurotensin, Melander explained.
The researchers hypothesized that the neurotensin system might play a role in the development of diseases related to excess weight, which include diabetes, breast cancer and heart disease.
To test that theory, they analyzed blood samples from more than 4,600 people who had volunteered for the Malmo Diet and Cancer Study between 1991 and 1994. The median follow-up time for each person was between 13 and 16 years.
The research team found a statistically significant relationship between proneurotensin levels in women and the risk of heart disease, diabetes and breast cancer. The odds of a woman developing type 2 diabetes increased by 41 percent with higher levels of proneurotensin. The likelihood of heart disease was 33 percent higher, while the odds of breast cancer jumped by 44 percent with higher proneurotensin. The odds of dying from heart disease rose by 50 percent with higher proneurotensin levels, according to the study.
"Proneurotensin is the first blood biomarker ever that can independently identify elevated risk of the three major disease threats to women's health and, accordingly, a high fasting blood concentration of proneurotensin is associated with earlier death," Melander said.
Once identified, these women may benefit from intensified primary prevention for cardiovascular disease and intensified screening for breast cancer, Melander noted. In the future, drugs that lower levels of neurotensin or block its action could be developed, he added.
Melander said the researchers don't know why higher levels of proneurotensin were indicative of health problems in women but not in men, although they suspect that estrogen likely played a role.
"Studies of animal models have clearly shown that the female sex hormone estrogen stimulates the growth of cells producing neurotensin, and women obviously have a higher lifetime exposure to estrogen than men," Melander said.
Although the study found an association between higher levels of proneurotensin and increased risk of certain diseases and death, it did not show a cause-and-effect relationship.
Dr. Minisha Sood, an endocrinologist at Lenox Hill Hospital in New York City, welcomed the study results.
These findings "suggest that there is an underlying neurotensin resistance in patients who will develop diabetes down the line; from this resistance stems a compensatory increase in the levels of proneurotensin," Sood explained.
"The findings also highlight an important mechanism by which to explain the increased rates of cancer and cardiovascular disease which are known to occur in obese patients," she added.
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