Androgens in Health and Disease.pdf - E Library

Chapter 18/Androgens in Older Men 353
Table 2
Possible Benefits and Risks of ART
Benefits Risks
Preserve/improve bone mass and prevent fractures Promote fluid retention
Increase muscle mass and strength Precipitate or worsen sleep apnea
Increase stamina and physical function Cause gynecomastia
Decrease cardiovascular disease risk Increase cardiovascular disease risk
Improve libido Produce polycythemia
Improve aspects of cognition
Improve well-being and mood Hasten development of benign or
malignant prostate disease
Table 2 lists the possible benefits and risks of ART. Many of these have been evaluated
in some form in the various ART trials, although there are very little data in some areas.
ART and Bone
Studies of ART in older men that have dealt with some aspect of the effect on bone
have all utilized T as the treatment androgen. This may be important, because T is
converted to estradiol in vivo and older men receiving ART often show a substantial
increase in serum estradiol levels. Because bioavailable estradiol has been shown to be
a better predictor of BMD in older men than any component of T, it is possible that the
effects of ART on bone in older men could be mediated through its conversion to
estradiol.
The published ART studies to date have lasted from 3 to 36 mo, with the shorter
studies measuring biochemical parameters of bone turnover and the longer studies
evaluating bone mineral density. Some, but not all, of the studies enrolled older men who
were osteoporotic at baseline. There are, as yet, no data on the effect of ART on fracture
rates in older men.
As shown in Table 3, these studies have generally shown an increase in BMD and a
slowing of bone degradation with ART (76–81). One other study in older men taking
chronic glucocorticoids reported an increase in vertebral BMD with T treatment (82).
The studies of ART have varied considerably in the baseline T levels of participants, in
the T levels achieved with therapy, and in the length of treatment. These differences,
along with the lack of knowledge about the serum T levels or length of treatment needed
to achieve optimal effects on BMD, may explain some of the discrepancy between the
findings of the various studies.
ART and Body Composition and Strength
There have been a number of published studies in which body composition and/or
muscle strength were evaluated during androgen therapy in older men (76,77,80,83–88).
In general, these studies have demonstrated a decline in fat mass and an increase in lean
body mass (LBM) with ART (see Table 4). The decline in fat mass that is seen in some
of the studies might be expected to lead to an improvement in insulin sensitivity, as was
shown in one study of obese nondiabetic men (85). A recent study, however, reported