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Licensed Unlicensed Requires Authentication Published by De Gruyter June 11, 2014

A simple method for estimating equilibrium constants for serum testosterone binding resulting in an optimal free testosterone index for use in elderly men

  • H. Alec Ross , Eric J. Meuleman and Fred C. G. J. Sweep

Abstract

An algorithm was developed to evaluate equilibrium constants for testosterone (Te) and sex hormone-binding globulin (SHBG) or albumin from serum free testosterone (FTe) measurements performed in a panel of 30 healthy elderly men by means of a near-reference method, i.e., symmetric dialysis (affinity constants: SHBG-Te, 1.13×10 9L/mol; albumin-Te, 4.4×10 4L/mol). Using these estimates, a free testosterone index (FTeI) was calculated from total Te and SHBG concentrations in a further 35 elderly men. This FTeI perfectly matches with actually measured free testosterone concentrations by symmetric dialysis in this second group, with a mean ratio index/measurement of 0.998±0.016 (SEM). The efficacy of the algorithm, which represents a simple alternative to previous cumbersome methods for estimation of equilibrium constants, is thereby demonstrated.


Corresponding author: H. Alec Ross, 530 Department of Chemical Endocrinology, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands Fax: +31-24-3541484,

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Received: 2004-12-8
Accepted: 2005-3-30
Published Online: 2014-6-11
Published in Print: 2005-6-1

© Walter de Gruyter Berlin New York

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