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Testosterone Replacement
Therapy (TRT) Beneficial In Men 60 And Older
New
study finds testosterone injections improve bone density markers in older
men; first known study to report on the impact of bone metabolism based on
dosing regimen
SAN DIEGO, CA – The risk of osteoporosis (bone
fracture) in women is highly recognized by the public. Less appreciated is
the fact that the disorder also occurs in men. Some two million males have
been diagnosed with osteoporosis and another three million are at risk.
Gender-based hormones and age are thought to be major
factors behind bone fractures in both sexes. Women with low levels of
estrogen and men with low levels of the testosterone are known to be at
risk. Low levels of gender hormones can lead to diminished bone mineral
density (BMD; also known as bone mass). Reduced bone density or bone mass
means there is less cushioning to protect the bone from cracking in a slip
or fall.
For this reason, testosterone replacement therapy (TRT)
is the standard of care used to improve bone strength and muscle mass in
males. However, TRT use has been the subject of some controversy. Continuous
testosterone use has been associated with prostate cancer and high red blood
cell levels, and its other effects are not fully known.
In one of the first clinical trials involving men over
60-85 years of age, researchers’ preliminary results indicate that
testosterone treatment for five months has a positive effect on the bone
markers of older men. This is the first known study to report on the impact
of bone metabolism based on dosing schedules.
Presentation at the 121st Annual Meeting
of the American Physiological Society
The study was conducted by E. Lichar Dillon, Randall J.
Urban, James A. Angel, Shanon L. Casperson and Melinda Sheffield-Moore, all
of the Department of Internal Medicine, University of Texas Medical Branch,
Galveston, TX; and Douglas Paddon-Jones of the Department of Rehabilitation
Sciences and Physical Therapy, the University of Texas Medical Branch. Their
study was funded in part by the National Institutes of Health (NIH) and is
entitled Continuous Testosterone Administration for Five Months
Reduces Markers of Bone Turnover in Older Men. Dr. Dillon is presenting
the team’s preliminary findings at the 121st Annual Meeting of
the American Physiological Society (APS;
www.the-APS.org/press), part of the Experimental Biology 2008 scientific
conference.
Study Summary
Thirteen older men between 60 – 85 years have thusfar
participated in the study. Testosterone levels ranged between 200-500
nanograms (ng) of testosterone per deciliter of blood (dL) at the time of
enrollment. (Normal limits are considered 250-800.) Each was enrolled in one
of three double-blinded groups: (1) those receiving continuous weekly
intramuscular injections of testosterone (100 mg testosterone-enanthate) for
the entire five month period (TE; n=4); (2) those receiving weekly
testosterone every other month (one month of weekly testosterone/one month
of weekly placebo; MO; n=4); or (3) those receiving a weekly placebo for the
entire five month period (PL; n=5).
The participants visited the clinic weekly for either
scheduled treatment injections or placebos. Volunteers received a baseline
whole-body Dual Energy X-Ray Absorptiometry (DEXA) scan at the beginning and
end of the study. Dietary records were obtained and analyzed at month zero,
month three and month five. Fasting blood samples were collected at regular
intervals throughout the study to examine serum markers of bone metabolism.
The Preliminary Study Results
The research team found that:
testosterone administration appears to reduce bone turnover,
perhaps closing the gap between resorption and formation
thusfar, the impact on bone mineral density are unclear but
may become more apparent as the study progresses.
the effects of testosterone on long-term bone metabolism are
unclear, but are expected to have at least a protective effect on existing
bone mass over time by preventing unwanted increases in bone turnover that
are frequently associated with osteoporosis. Osteoporosis is often
associated with high bone turnover (increases in bone resorption as well as
in bone formation) which results in decreased BMD.
Conclusions
According to Dr. Dillon, the study’s first author,
“These preliminary data show beneficial effects of testosterone therapy on
bone turnover markers in older men with low-to-normal testosterone
concentrations using both continuous and monthly cycled testosterone
replacement.” He added, “The effects of sex hormones on markers of bone
formation are complex, but this is an important step in understanding how
the process works.”
*****
Physiology
is the study of how molecules, cells, tissues and organs function to create
health or disease. The American Physiological Society (APS;
www.The-APS.org/press) has been an integral part of this discovery
process since it was established in 1887.
# # #
NOTE TO EDITORS: The APS annual meeting is part
of the Experimental Biology 2008 (EB ’08) gathering and will be held April
5-9, 2008 at the San Diego, CA Convention Center. To schedule an interview
with Dr. Dillon please contact Donna Krupa at 301.634.7209 (office),
703.967.2751 (cell) or
DKrupa@the-APS.org.
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