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Measurement‐specific bioavailable testosterone using concanavalin A precipitation: Comparison of calculated and assayed bioavailable testosterone
Author(s) -
Yamamoto Kenrou,
Koh Eitetsu,
Matsui Futoshi,
Sugimoto Kazuhiro,
Sin HoSu,
Maeda Yuji,
Namiki Mikio
Publication year - 2009
Publication title -
international journal of urology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 67
eISSN - 1442-2042
pISSN - 0919-8172
DOI - 10.1111/j.1442-2042.2009.02379.x
Subject(s) - concanavalin a , testosterone (patch) , medicine , bioavailability , sex hormone binding globulin , globulin , endocrinology , serum concentration , chromatography , hormone , androgen , pharmacology , chemistry , biochemistry , in vitro
Objective: To assess the value of calculated bioavailable testosterone (cBT) and assayed BT (aBT) for the diagnosis of late‐onset hypogonadism (LOH) in middle‐aged and elderly subjects. Methods: In order to assay serum BT, sex hormone‐binding globulin was precipitated with concanavalin‐A and then testosterone was measured using liquid chromatography‐tandem mass spectrometry. To validate the non‐sex‐hormone‐binding‐globulin‐bound testosterone, gel filtration chromatography and concanavalin‐A sepharose were used. Following this validation, the usefulness between aBT and cBT was evaluated in clinical samples. Results: Eighty‐eight healthy male volunteers (mean age 65.6 years, range: 50–86) were recruited for this study. A significant correlation was found between cBT and aBT (R 2 = 0.53, P < 0.01). Mean value ratio (cBT/aBT) was 2.48. Both cBT (R 2 = 0.122) and aBT (R 2 = 0.251) decreased with age. Variations in aBT were less marked than those for cBT, suggesting that aBT can be used to determine age‐related reduced testosterone levels. Conclusion: aBT levels are more reliable than cBT levels for the diagnosis of LOH in middle‐aged and elderly subjects.