Insulin-Like Hormone May Hold Key to Longer Life for
Elderly Men
New way of testing opens the possibility to new
insights about IGF-1
May
27, 2008 - A new study of elderly men with higher activity of the
hormone IGF-1 - insulin-growth factor 1 - appear to have greater life
expectancy and reduced cardiovascular risk, according to a report on
research that used a new method of testing for IGF-bioactivity.
IGF-1 is a hormone similar in molecular structure
to insulin. It is released from the liver and plays an important role in
childhood growth and continues to have anabolic effects in adults.
In this study, researchers evaluated 376 healthy
elderly men between the ages of 73 and 94 years. A serum sample was
taken from each subject at the beginning of the study and researchers
were contacted about the status of the participants over a period of
eight years.
Subjects with the lowest IGF-1 function had a
significantly higher mortality rate than subjects with the highest IGF-1
bioactivity. These results were especially significant in individuals
who have a high risk to die from cardiovascular complications.
These new findings come as a result of a new form
of testing for IGF-bioactivity. Researchers in this study used a new
method, a bioassay, to measure the function of IGF-1 in the blood.
Compared to commonly used methods to measure IGF-1, the IGF-1 bioassay
gives more information about the actual function (bioactivity) of
circulating IGF-1 in the body.
The bioassay allowed us to more clearly see the
association between high circulating IGF-1 bioactivity and extended
survival, said Michael Brugts, MD, of the Erasmus Medical Center in
Rotterdam, The Netherlands and lead author of the study.
Interestingly, we could not find such a
relationship when IGF-1 in blood was measured with the more commonly
used methods.
Immunoassays, commonly used previously to determine
IGF-1 circulation levels, remove certain proteins that interfere with
accurate measurements. Recent studies however have found that these
proteins are important modulators of IGF-1 bioactivity. The bioassay
used in this study does not disregard or remove this protein, thus
enabling researchers to have a more accurate understanding of IGF-1
function.
Determination of IGF-1 function using the bioassay
opens the possibility to gather new insights about the functions of
IGF-1 in the body, said Brugts.
The study report has been accepted for publication
in the Journal of Clinical Endocrinology & Metabolism (JCEM).
Editors Notes:
Other researchers working on the study include A.W.
Van den Beld, L.J. Hofland, K. van der Wansem, P.M. van Koetsveld, S.W.J.
Lamberts, and J.A.M.J.L. Janssen of Erasmus Medical Center in Rotterdam,
The Netherlands and J. Frystyk of Aarhus University Hospital in Aarhus,
Denmark.
The article Low Circulating IGF-1 Bioactivity in
Elderly Men is Associated with Increased Mortality, will appear in the
June issue of JCEM, a publication of The Endocrine Society.
Keep up with the latest news for senior citizens, baby
bommers
May
27, 2008 - A new study of elderly men with higher activity of the
hormone IGF-1 - insulin-growth factor 1 - appear to have greater life
expectancy and reduced cardiovascular risk, according to a report on
research that used a new method of testing for IGF-bioactivity.