Public Release: 

The Endocrine Society responds to Institute of Medicine report on testosterone therapy for older men

The Endocrine Society

November 17, 2003, Chevy Chase, MD - The Endocrine Society, the largest and most active professional organization of endocrinologists in the world, today announced its support for the Institute of Medicine (IOM) report titled Testosterone and Aging: Clinical Research Directions. The report was drafted by a panel of experts formed in November 2002 to review and assess the current state of knowledge related to the health risks and benefits of testosterone therapy in aging men. It sets forth recommendations for clinical trials of testosterone therapy, including specific parameters that should be considered in study design and conduct.

The Endocrine Society agrees with the panel's key conclusions and believes that it is critical that the medical community determine whether testosterone treatment results in clear benefits for aging men before long-term trials are conducted. Additionally, the Society agrees that testosterone therapy should be evaluated initially as a therapeutic, not as a preventive measure for aging men. Finally, it is reasonable that clear short-term benefits of testosterone therapy be established in testosterone deficient men over the age of 65 before committing the time, energy and cost of a properly powered study of the long-term benefits and risks of testosterone therapy in this age group.

The Endocrine Society supports the IOM panel in their efforts to help the public and the medical community better understand the existing body of knowledge on testosterone therapy and develop directions for future clinical studies on testosterone therapy for older men.

The Endocrine Society supports the IOM recommendations for future clinical trials on testosterone, which include:

  • Conduct clinical trials on older men with low testosterone levels.
  • Begin with short-term, randomized double-blind, placebo-controlled efficacy trials to determine the benefits of testosterone therapy in older men. Furthermore, these trials should be coordinated, in order to provide for standardization of data collection across sites and aggregate data analysis, and pooling of short-term risk.
  • Conduct longer-term studies if short-term efficacy is established.
  • Ensure the safety of research participants.
  • Conduct further research to investigate physiologic regulation, mechanism of action and age-related changes in testosterone levels.

The IOM recommends that initial studies be conducted in men over the age of 65 who have low serum testosterone levels and at least one symptom that might be related to low testosterone. Endocrinologists have played a crucial and leading role in defining the clinical manifestations of androgen deficiency, developing appropriate and sensitive assay methods to measure testosterone concentrations in blood and developing and testing testosterone formulations for therapy of men with hypogonadism, a condition characterized by low testosterone levels. The Endocrine Society notes that several factors should be considered when setting up the protocol for the measurement of testosterone in study participants. One of the issues addressed in the IOM detailed report pertains to the definition of a "normal range" for testosterone in healthy men. Currently, reference range varies depending on the type and manufacturer of the test used for measurement. Since a primary criterion for selection of study participants is a low testosterone level, it will be crucial to address the problem of lack of standardization in reference range for serum testosterone. Also, it is unclear what level of testosterone should be considered low and associated with disability or symptoms. In addition to this area of concern, it will also be important to include other tests in the laboratory measurements obtained for each study participant. Total testosterone levels may be affected by several factors including the level of protein in the blood that transports the hormone in the body, age, obesity and interferences associated with commonly used test methods. More meaningful blood tests, which should be considered for the study population (i.e. men over 65 years), are bioavailable or free serum testosterone. It is also important to collect blood samples for hormone measurement in the morning hours from seven to 10 a.m., and to confirm results with a repeat measurement in order to obtain meaningful results. Finally, The Endocrine Society notes that a clear diagnosis of hypogonadism in men of all ages remains an established indication for testosterone therapy.

In 2000 and 2001, the Endocrine Society convened a panel of authorities in various areas of medicine, including endocrinology, urology, psychiatry and primary care, to perform an in depth review of the issues pertaining to androgen deficiency in aging men. The conferences were held to evaluate the current research on testosterone therapy and to develop recommendations for testosterone therapy that could be used in a clinical setting. Additionally, the group examined the defined levels of testosterone in young and older men. The panel concluded that there was insufficient data to provide definitive answers to the problems that were addressed. Instead, the panel created recommendations that were designed to provide guidance and assist practitioners until more adequate information is available.

"Endocrinologists are deeply involved with the treatment and research of testosterone therapy for men of all ages. The Endocrine Society recognizes that clinical trials are needed to better understand the impact of testosterone treatment on aging men. We applaud the IOM panel for evaluating our current knowledge of testosterone therapy and for determining the most appropriate way to conduct future research in the area of testosterone therapy for men over 65," noted Endocrine Society President, E. Chester Ridgway. "We hope that the scientific community will follow the recommendation of the IOM panel. It is also important to define what constitutes a low testosterone in men under age 65 and to study the effects of testosterone replacement therapy in those individuals."


Founded in 1916, The Endocrine Society is the world's oldest, largest, and most active organization devoted to research on hormones, and the clinical practice of endocrinology. Endocrinologists are specially trained doctors who diagnose, treat and conduct basic and clinical research on complex hormonal conditions such as diabetes, thyroid disease, osteoporosis, obesity, hypertension, cholesterol and reproductive disorders. Today, The Endocrine Society's membership consists of over 11,000 scientists, physicians, educators, nurses and students, in more than 80 countries. Together, these members represent all basic, applied, and clinical interests in endocrinology. The Endocrine Society is based in Chevy Chase, Maryland. To learn more about the Society, and the field of endocrinology, visit the Society's web site at

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.