Determination of the reference values of total testosterone, calculated free testosterone, calculated bioavailable testosterone and salivary testosterone in young, healthy population of the Mediterranean area
Víctor Luis González-Sánchez1, Oscar Moreno-Pérez1, Luis García de Guadiana Romualdo2, Pedro Sánchez Pellicer3, Monserrat Mauri Dot2, José Sánchez Paya4 & Antonio Miguel Picó Alfonso1
Introduction: Free testosterone (FT) and bioavailable testosterone (BT), are better surrogate markers of the androgenic status of the individual than total testosterone (TT). Calculated FT (CFT) and calculated BT (CBT) which take into consideration the kinetics of the bond between FT and albumin and SHBG, provide results practically identical to those of the reference techniques. Salivary testosterone (Sal-T) is a promising tool in the study of gonadal pathology. The interassay variability justifies the need for each laboratory establish reference intervals for these determinations.
Objective: To obtain reference values for TT, CFT, CBT, and Sal-T in healthy young population in the Mediterranean area for the proper study of gonadal function in our center.
Methods: Cross-sectional study. Sequential sampling. Inclusion criteria: healthy men, 1830 years, BMI<30. Sample size: 127 individuals. Methodology: TT (ng/ml; chemiluminescence immunoassay), CFT and CBT (ng/dl; Vermulen et al.), Sal-T (pg/ml; RIA for TT in saliva specimen). Descriptive statistics (SPSS 15.0).
Results: We studied 127 eugonadal men, 24±3 years, SBP 116±12 mmHg, DBP 69±8 mmHg, BMI 24±3. Hormonal reference values: TT 5.4±1.6 ng/ml (P2.5 2.8P97.5 9.6), CFT 11.1 ng/dl (P2.5 6.3P97.5 22.2), CBT 281 ng/dl (P2.5 143P97.5 550) and Sal-T 94.2 pg/ml (P2.5 53.2P97.5 195.8).
Conclusions: i) The reference values for healthy young population in the Mediterranean area for TT are between 2.8 and 9.6 ng/ml, calculated Free-T 6.322.2 ng/dl, calculated Bio-T 143551 ng/dl and Sal-T 53.2195.8 pg/ml. ii) It is necessary that each laboratory validate the method and determine its own reference intervals in order to establish reliable cut-off values in the diagnosis of hypogonadism.