The growth hormone, insulin-growth factor-1 (IGF-1) is similar in molecular structure to insulin. It is released by the liver and also regulates childhood growth and continues to have anabolic effects in adults.
Researchers evaluated 376 healthy men aged between 73 and 94 years. A serum sample was taken from each subject at the beginning of the study. Researchers tracked their status over eight years.
Subjects with the lowest IGF-1 expression had a higher mortality rate than subjects with the highest IGF-1 activity. These results were significant in individuals at risk from cardiovascular complications.
Researchers used a new method, a bioassay, to measure the function of IGF-1. Compared to existing techniques, bioassay gives more information about the actual function of circulating IGF-1.
“The bioassay allowed us to more clearly see the association between high circulating IGF-1 bioactivity and extended survival,” said Michael Brugts of the Erasmus Medical Centre, Rotterdam, and co-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.”
Findings of the study are slated to appear in the forthcoming issue of the Journal of Clinical Endocrinology & Metabolism.