|
Taken from WWW.pubmed.gov (testosterone studies)
Eur J Endocrinol. 2007 May;156(5):585-94.
In men older than 70 years, total testosterone remains stable while free testosterone
declines with age. The Health in Men Study.
Yeap BB, Almeida OP, Hyde Z, Norman PE, Chubb SA, Jamrozik K, Flicker L.
School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia,
Australia. byeap@cyllene.uwa.edu.au
OBJECTIVE: An age-related decline in serum total and free testosterone concentration may contribute
to ill health in men, but limited data are available for men > 70 years of age. We sought to
determine the distribution and associations of reduced testosterone concentrations in older men.
DESIGN: The Health in Men Study is a community-representative prospective cohort investigation of 4263
men aged > or = 70 years. Cross-sectional hormone data from 3645 men were analysed.
METHODS: Early morning sera were assayed for total testosterone, sex hormone binding globulin (SHBG)
and LH. Free testosterone was calculated using the Vermeulen method.
RESULTS: Mean (+/- s.d.) serum total testosterone was 15.4 +/- 5.6 nmol/l (444 +/- 162 ng/dl),
SHBG 42.4 +/- 16.7 nmol/l and free testosterone 278 +/- 96 pmol/l (8.01 +/- 2.78 ng/dl). Total
testosterone correlated with SHBG (Spearman's r = 0.6, P < 0.0001). LH and SHBG increased with
age (r = 0.2, P < 0.0001 for both). Instead of declining, total testosterone increased marginally
(r = 0.04, P = 0.007) whilst free testosterone declined with age (r = -0.1, P < 0.0001). Free
testosterone was inversely correlated with LH (r = -0.1, P < 0.0001). In multivariate analyses,
increasing age, body mass index (BMI) and LH were associated with lower free testosterone.
CONCLUSIONS: In men aged 70-89 years, modulation of androgen action may occur via an age-related
increase in SHBG and reduction in free testosterone without a decline in total testosterone
concentration. Increasing age, BMI and LH are independently associated with lower free testosterone.
Further investigation would be required to assess the clinical consequences of low serum free
testosterone, particularly in older men in whom total testosterone may be preserved.
PMID: 17468195 [PubMed - indexed for MEDLINE]
Dr. Gordon:
Most, if not almost all, past studies have used the total testosterone test.
> The numbers of people suffering from testosterone deficiency have been greatly underestimated.
> Many study subjects who were considered to be healthy were actually deficient in testosterone rendering
the conclusions of the studies highly questionable and probably understated.
|
