@article{oai:kanazawa-u.repo.nii.ac.jp:00014096,
 author = {Taya, Masaki and Koh, Eitetsu and Izumi, Kouji and Iijima, Masashi and Maeda, Yuji and Matsushita, Tomohiko and Iwamoto, Teruaki and Namiki, Mikio},
 issue = {7},
 journal = {International Journal of Urology},
 month = {Jul},
 note = {Objectives: To determine testosterone fractions in Japanese men and to compare these values with those of Framingham Heart Study participants. Methods: We enrolled 498 healthy Japanese men. Total testosterone was assayed by liquid chromatography tandem mass spectrometry, sex hormone-binding globulin was assayed by immunoassay and free testosterone was calculated by a laboratory at the Boston Medical Center. Analog-based free testosterone and immunoassay-based total testosterone were determined by immunoassay. We compared mass spectrometry assay-based total testosterone and calculated free testosterone values in the Japanese participants with values in the American Framingham Heart Study third generation cohort. Results: The mean serum mass spectrometry assay-based total testosterone, sex hormone-binding globulin, and calculated free testosterone values were 439.4±167ng/dL, 65.34±30.61nmol/L, and 58.75±20.0pg/mL, respectively. The correlation coefficients with age for mass spectrometry assay-based total testosterone, sex hormone-binding globulin, and calculated free testosterone were 0.0010, 0.5041, and -0.496, respectively. There were no age-related changes in mass spectrometry assay-based total testosterone values in healthy men (P=0.981), whereas sex hormone-binding globulin and calculated free testosterone levels showed similar age-related changes (P<0.0001). Serum analog-based free testosterone levels (8.24±2.9pg/mL) showed age-related changes (P<0.0001) regardless of immunoassay-based total testosterone levels (P=0.828). Serum immunoassay-based total testosterone values (486.1±162.5ng/dL) correlated with serum mass spectrometry assay-based total testosterone values (r=0.740, 95% confidence interval 0.6965-0.7781, P<0.0001). Similarly, analog-based free testosterone and calculated free testosterone values showed a highly significant correlation (r=0.706, 95% confidence interval 0.6587-0.7473, P<0.0001). The analog-based free testosterone values were approximately 10% of the calculated free testosterone values. Conclusions: In contrast to the Framingham Heart Study cohort, total testosterone values in Japanese men are not associated with advancing age; thus, they cannot be used to diagnose late-onset hypogonadism in Japan. The analog-based free testosterone value can be considered instead as a suitable biochemical determinant for diagnosing late-onset hypogonadism syndrome. © 2014 The Japanese Urological Association.},
 pages = {689--695},
 title = {Comparison of testosterone fractions between Framingham Heart Study participants and Japanese participants},
 volume = {21},
 year = {2014}
}