Calculation of Bioavailable and Free Testosterone in Men: A Comparison of 5 Published Algorithms Export

@article{citeulike:4486461, abstract = {Background: Estimation of serum concentrations of free testosterone (FT) and bioavailable testosterone (bioT) by calculation is an inexpensive and uncomplicated method. We compared results obtained with 5 different algorithms. Methods: We used 5 different published algorithms [described by Sodergard et al. (bioTS and FTS), Vermeulen et al. (bioTV and FTV), Emadi-Konjin et al. (bioTE), Morris et al. (bioTM), and Ly et al. (FTL)] to estimate bioT and FT concentrations in samples obtained from 399 independently living men (ages 40-80 years) participating in a cross-sectional, single-center study. Results: Mean bioT was highest for bioTS (10.4 nmol/L) and lowest for bioTE (3.87 nmol/L). Mean FT was highest for FTS (0.41 nmol/L), followed by FTV (0.35 nmol/L), and FTL (0.29 nmol/L). For bioT concentrations, the Pearson correlation coefficient was highest for the association between bioTS and bioTV (r = 0.98) and lowest between bioTM and bioTE (r = 0.66). FTL was significantly associated with both FTS (r = 0.96) and FTV (r = 0.88). The Pearson correlation coefficient for the association between FTL and bioTM almost reached 1.0. Bland-Altman analysis showed large differences between the results of different algorithms. BioTM, bioTE, bioTV, and FTL were all significantly associated with sex hormone binding globulin (SHBG) concentrations. Conclusion: Algorithms to calculate FT and bioT must be revalidated in the local setting, otherwise over- or underestimation of FT and bioT concentrations can occur. Additionally, confounding of the results by SHBG concentrations may be introduced. 10.1373/clinchem.2005.063354}, author = {de Ronde, Willem and van der Schouw, Yvonne T. and Pols, Huibert A. and Gooren, Louis J. and Muller, Majon and Grobbee, Diederick E. and de Jong, Frank H.}, citeulike-article-id = {4486461}, citeulike-linkout-0 = {http://dx.doi.org/10.1373/clinchem.2005.063354}, citeulike-linkout-1 = {http://www.clinchem.org/cgi/content/abstract/52/9/1777}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/16793931}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=16793931}, day = {1}, doi = {10.1373/clinchem.2005.063354}, journal = {Clin Chem}, keywords = {free, testosterone}, month = {September}, number = {9}, pages = {1777--1784}, posted-at = {2009-05-07 13:49:13}, priority = {2}, title = {Calculation of Bioavailable and Free Testosterone in Men: A Comparison of 5 Published Algorithms}, url = {http://dx.doi.org/10.1373/clinchem.2005.063354}, volume = {52}, year = {2006} }

TY - JOUR ID - citeulike:4486461 L3 - citeulike-article-id:4486461 N2 - Background: Estimation of serum concentrations of free testosterone (FT) and bioavailable testosterone (bioT) by calculation is an inexpensive and uncomplicated method. We compared results obtained with 5 different algorithms. Methods: We used 5 different published algorithms [described by Sodergard et al. (bioTS and FTS), Vermeulen et al. (bioTV and FTV), Emadi-Konjin et al. (bioTE), Morris et al. (bioTM), and Ly et al. (FTL)] to estimate bioT and FT concentrations in samples obtained from 399 independently living men (ages 40-80 years) participating in a cross-sectional, single-center study. Results: Mean bioT was highest for bioTS (10.4 nmol/L) and lowest for bioTE (3.87 nmol/L). Mean FT was highest for FTS (0.41 nmol/L), followed by FTV (0.35 nmol/L), and FTL (0.29 nmol/L). For bioT concentrations, the Pearson correlation coefficient was highest for the association between bioTS and bioTV (r = 0.98) and lowest between bioTM and bioTE (r = 0.66). FTL was significantly associated with both FTS (r = 0.96) and FTV (r = 0.88). The Pearson correlation coefficient for the association between FTL and bioTM almost reached 1.0. Bland-Altman analysis showed large differences between the results of different algorithms. BioTM, bioTE, bioTV, and FTL were all significantly associated with sex hormone binding globulin (SHBG) concentrations. Conclusion: Algorithms to calculate FT and bioT must be revalidated in the local setting, otherwise over- or underestimation of FT and bioT concentrations can occur. Additionally, confounding of the results by SHBG concentrations may be introduced. 10.1373/clinchem.2005.063354 IS - 9 JF - Clin Chem EP - 1784 TI - Calculation of Bioavailable and Free Testosterone in Men: A Comparison of 5 Published Algorithms VL - 52 SP - 1777 KW - free KW - testosterone AU - de Ronde, Willem AU - van der Schouw, Yvonne AU - Pols, Huibert AU - Gooren, Louis AU - Muller, Majon AU - Grobbee, Diederick AU - de Jong, Frank PY - 2006/09/01/ UR - http://dx.doi.org/10.1373/clinchem.2005.063354 ER -