Valoración de niveles de testosterona mediante diferentes métodos analíticos en varones sanos

Abstract

Plasma testosterone concentrations are essential for the diagnosis of several causes of hypogonadism, including late-onset hypogonadism. Defining the normal range for testosterone concentrations poses certain difficulties due to the changes that occur with age and the variability of the different analytical methods used. Objectives To study normal ranges of testosterone in healthy young men and to compare the results of distinct analytical methods. Material and methods We recruited 20 healthy men with a mean age of 24.5 years (standard deviation (SD): 5.04) and a mean body mass index (BMI) of 23.8% (SD: 3.3). Total testosterone (TT) was measured by immunochemiluminescence (ICLA) and free testosterone (FT) by radioimmunoassay (RIA). Calculated free testosterone (FTc) and bioavailable testosterone (BT) were calculated using Vermeulen's formula. Serum lutropin (LH), follitropin (FSH) and sex hormone binding globulin (SHBG) were measured by immunoradiometric assays (IRMA). Results The mean concentrations were 20 nmol/l (SD: 4.96) for TT, 0.054 nmol/L (SD: 0.01) for FT, 0.3834 nmol/L (SD: 0.09) for FTc and 9.9 nmol/L (SD: 2.8) for BT. There was no correlation between testosterone measured by different methods other than an association between FT and FTc ( r=0.662, p<0.003) and between FTc and BT ( r=0.979, p<0.0001). An inverse correlation was found between BMI and TT concentrations ( r: −0.52, p<0.017). Conclusions The normal range for testosterone in healthy young men should be established in each laboratory based on the analytical method used.