Age-related change in serum concentrations of testosterone in middle-aged Korean men

The objective of this study was to determine whether testosterone and sex hormone binding globulin (SHBG) levels are different between healthy men and men with chronic illness, and to evaluate the age-related changes of testosterone and SHBG in healthy men in Korea. enrollment took place between January 2000 and December 2001 at Pundang CHA General Hospital in Korea. All men who came for male climacteric and geriatric health screening examinations were eligible. Of the 762 men recruited, 136 men had at least one present or previous medical illness and 626 men were healthy. Higher serum concentrations of total testosterone (5.31 +/- 1.88 ng/ml vs. 4.96 +/- 1.43 ng/ml; p < 0.05), free androgen index (16.60 +/- 7.36 vs. 14.57 +/- 5.55; p < 0.01) and calculated bioavailable testosterone (8.88 +/- 3.52 nmol/l vs. 7.91 +/- 2.52 nmol/l; p < 0.01) were demonstrated in the healthy compared with the disease group. Total testosterone declined at a rate of 0.2% per year, SHBG increased by 1.74% per year, calculated bioavailable testosterone declined by 0.8% per year, and free androgen index declined by 1.15% per year in healthy subjects aged between 40 and 70. The above results seem to be consistent with previous Western studies, showing higher concentrations of testosterone in healthy men, that decline with increasing age.