Investigating Alternative Methods of Assessing the Androgen Status of Males

David Kennedy, Biochemistry

DM Kennedy, H Kazi and A Proudler

Traditionally measurement of serum total testosterone (TT) has been central to the investigation of suspected hypogonadism in men. However, TT has a high intra-individual variability, hence many normal men ocasionally have TT levels in the hypogonadal range.  Also animal studies suggest that bioavailable testosterone (BAT), free testosterone (FT) plus albumin bound testosterone, more accurately reflects true androgen status.  Both FT and BAT can be measured directly or estimated by a variety of equations.

We have developed an ammonium sulphate (AS) precipitation method for the Roche E170 immunoassay analyser enabling measurement of BAT.  Using 70% AS showed good separation of the globulin and albumin fractions but interfered with the immunoassay.  Dilution of the AS supernate with serum based diluent followed by measurement of BAT by direct immunoassay produced results that compared well with estimated BAT.  FT was also measured by immunoassay and correlated significantly (n=17, R=0.62, P=0.01) with estimated FT, using the Vermeulen equation, however the measured results were much lower (estimated FT = 15.33 × measured FT-0.0052).

Further work is needed to confirm the AS precipitation method is robust with the Roche immunoassay.  However, this precipitation method could also be used in conjunction with the LC/MSMS method recently developed at Heartlands to create a potentially novel method.