Endocrine Abstracts

Reference ranges are the most common decision support tool used for results interpretation and so a very relevant part of the laboratory report. Their use has become increasingly prevalent in clinical practice. A low serum testosterone (T) level in combination with clinical signs and symptoms are required for hypogonadism diagnosis. The goal of this research was to establish the reference intervals of total testosterone (TT) from healthy adult males. The study sample consisted of 179 adult males aged 18 – 63 years and stratified into three age groups: 18-33, 34-42, and 43-63 years, with measured serum concentrations of TT by electrochemiluminescence immunoassay (Cobas e411®, Roche diagnostics). The 2.5th to 97.5th percentiles of subjects for TT were used as the normative range with parametric method. The mean serum TT level for the three age groups: 18-33, 34-42 and 43-63 years were 419±139, 387±135 and 379±134 ng/dl respectively. We found a statistically significant age-related decrease for serum concentrations of TT (P<0.001). The population mean TT was 394±136 ng/dl. The 95% reference interval (with 90% confidence interval) of serum TT from all participants ranged from 126 (97-155) to 662 (633-691) ng/dl. We generated reference ranges for total testosterone specific for our population using data from apparently healthy men, that could be used for results interpretation in our laboratory because population-specific reference ranges are needed to understand normal vs abnormal TT levels. This study can be helpful in broader research to calculate age-specific reference ranges and cutoffs of TT for the diagnosis of male hypogonadism.