The following highlights represent papers accepted for publication in the Journal of Clinical Endocrinology and Metabolism (JCE&M), as well as new patient information provided by The Hormone Foundation, the public education affiliate of The Endocrine Society.
Lifestyle Accelerates Testosterone Decline
Testosterone concentrations in men normally decline with age, but a new study confirms that many health and lifestyle changes can significantly accelerate that decline. Research reveals that a Body Mass Index (BMI) increase of only 4-5 points had the same diminishing effect on total testosterone as approximately 10 years of aging. A similar decline in testosterone was also associated with a traumatic emotional event, such as the loss of a spouse. "Understanding this phenomenon is important because low levels of testosterone may contribute to such conditions as diabetes, reduced bone and muscle mass, impaired sexual function, and a generally decreased quality of life," said Thomas G. Travison, PhD, lead author of the study.
The researchers analyzed data on 1,667 subjects enrolled in the Massachusetts Male Aging Study (MMAS), a longitudinal study of men's health and endocrine functioning. The MMAS tracked subjects' history of chronic illness, tobacco use, alcohol consumption, dietary intake, and physical activity.
This study provides compelling evidence that specific changes in health and lifestyle - such as an increase in BMI - are accompanied by an accelerated loss of serum testosterone. While these lifestyle changes cannot be proven to be the cause of associated testosterone declines, they appear at least as significant as - if not more than -- short to mid-term aging effects. These results suggest the possibility that age-related hormone decline could be minimized by managing health and lifestyle factors.
Obesity More than Doubles Testosterone in Pubertal Girls
Compared to their normal weight counterparts, obese girls have significantly higher levels of testosterone before and during puberty (i.e., the peripubertal phase). Researchers have found that mean concentrations of free serum testosterone in obese peripubertal girls were two-to-nine times higher than in normal weight peripubertal girls. This difference appeared to be especially prominent during the earlier pubertal stages. In addition to elevated testosterone concentrations, obese girls also had insulin concentrations that were up to three times higher than for normal weight girls. Increased insulin levels suggest insulin resistance, which also raises the specter of an increased risk of developing diabetes later in life.
For this study, researchers examined 30 normal weight girls and 74 obese girls, as measured by Body Mass Index (BMI) standardized for age, in various stages of puberty. The girls' pubertal stage was categorized by Tanner breast staging, which is the standard physical exam measure used by pediatricians.
The early stages of puberty (Tanner 1-3) are particularly critical times in a girl's development. "Since this is when the complex interactions governing the menstrual cycle are being established, excess testosterone during this time could impact the future reproductive health of women," said Dr. Christopher R. McCartney, lead author of the study. "Though, the long-term implications of elevated testosterone during puberty have yet to be established." McCartney also noted that high testosterone levels can promote excessive hair growth, though it could take a few years for these symptoms to materialize in subjects.