T05-P-05 Testosterone determination in biological fluids: problems and solutions

Abstract

Objectives Total serum testosterone (TT) assays play an important role in the clinical evaluation of various common endocrine disorders in man, women and children. However practically all commercial assays of TT are unreliable.(W. Rosner et al” Position statement: Utility, limitations and pitfalls in measuring testosterone”. JCEM, 92 (2); 405-413, 2007). In our study we compare the classical (with extraction) RIA method with five platform assay systems. The classical RIA method can be considered as a golden standart for TT measurement, (normal range 11- 34 nmol/L for healthy men). All tested non-isotopic immunoassay methods, excluding Vitros ECI, showed unacceptable positive bias, particularly for low T concentrations ( RIA results 95%); interference with binding proteins. Free testosterone (fT) circulating in plasma unbound to SHBG and albumin only 2%. Saliva as alternative fluid, attracted the attention of researches many years ago as salivary glands pass in the duct only free steroids. Our hypothesis was that salivary fT may be a suitable screening test for males and women with symptomatic androgen deficiency. Design and Methods Evaluation of diagnostic significance of ultra sensitive chemiluminescence technology (IBL, Hamburg) for determination fT in saliva, using different clinical models of androgenic status. We selected healthy male (n=31), male patients (n=40) with various etiologies of androgen deficiency, including metabolic syndrome, and healthy women age 17-30 yrs (n= 20), age 55-59 yrs (n=7). Results Salivary fT concentration levels in healthy men were 369 ( 263-544) pmol/L, in men with androgen deficiency 215 ( 51-249) pmol/L. In women age 17-30 years salivary fT concentration: 135( 83-218) pmol/L, 55-59 years - 95(55- 137) pmol/L. Conclusions Salivary fT measurement gives a good reflection of the unbound T in plasma. The technique of sampling is simple and non-invasive and can be widely used for the clinical diagnostics.