Endocrine markers of aging

Abstract

Sophisticated methods available to quantitate hormone secretion and hormone action provide opportunities to identify potential endocrine biomarkers of aging. However, there are many challenges facing the investigator who wishes to establish an endocrine biomarker. Circulating levels of many hormones fluctuate on a circadian rhythm, and a variety of other short-term fluctuations may occur. Hormone secretion is generally tightly regulated and often affected by multiple, redundant feedback mechanisms. Interpretation of circulating hormone levels must also take into account factors affecting hormone metabolism and degradation which may be influenced by age. The rate of hormone secretion and circulating hormone levels are related to the sensitivity to hormone action by feedback control mechanisms. Thus interpretation of potential circulating endocrine markers of aging must take into account changes in sensitivity to that hormone as well.