Reference ranges for serum and salivary testosterone in young men of Mediterranean region

The interassay variability found in the measurement of testosterone (T) levels warrants the need for laboratories to validate their methods to establish trustworthy cut-off points for diagnosis of male hypogonadism. The aims of this study were to validate measurement of total T (TT) at our laboratory in order to obtain reference ranges for TT, calculated free T (CFT), calculated bioavailable T (CBT), and salivary T (ST) in healthy young men from the Mediterranean region, and to evaluate the potential clinical value of ST by establishing its correlation with serum T.

An observational, cross-sectional study with sequential sampling.

men aged 18-30 years with body mass index (BMI)<30.

chronic diseases, hepatic insufficiency or use of drugs altering circulating T levels. Main outcome measures TT (chemiluminescent immunoassay UniCell DXI 800 [Access T Beckman Coulter]), CFT and CBT (Vermeulen's formula), and ST (radioimmunoassay for serum TT modified for saliva [Coat-A-Count, Siemens]). Descriptive statistical analyses and correlation by Spearman's rho (SPSS 19.0 Inc., Chicago) were used.

One hundred and twenty-one subjects aged 24±3.6 years with BMI 24±2.5 kg/m(2) were enrolled. Hormone study: TT, 19±5.5 nmol/L (reference range [rr.] 9.7-33.3); CFT, 0.38 nmol/L (rr. 0.22-0.79); CBT, 9.7 nmol/L (rr. 4.9-19.2); and ST, 0.35 nmol/L (rr. 0.19-0.68). Correlation between ST and CFT was 0.46.

In men from the Mediterranean region, values of TT>9.7 nmol/L, CFT>0.22 nmol/L, and/or CBT>4.9 nmol/L make the presence of biochemical hypogonadism unlikely. According to the correlation between serum and ST, the clinical value of ST remains to be established.