Are they functional hypogonadal men? Testosterone serum levels unravel male idiopathic infertility subgroups

To evaluate total testosterone distribution in male idiopathic infertility. A retrospective, real-world case-control clinical study was conducted. Cases consisted of men evaluated for couple infertility, specifically those with alterations in semen parameters and normal gonadotropin levels, and after excluding all known causes of male infertility. Controls were male subjects who underwent semen analysis for screening purposes, without any abnormality detected. The total testosterone distribution was evaluated in cases and controls. Further analyses were performed subgrouping cases according to total testosterone reference threshold suggested by scientific societies (i.e., 3.5 ng/mL). Cases included 214 idiopathic infertile men (mean age 38.2 ± 6.2 years) and controls 224 subjects with normozoospermia (mean age 33.7 ± 7.5 years). Total testosterone was not-normally distributed in both cases and controls, with positive asymmetric distribution slightly shifted on the left in cases. The rate of subjects with testosterone lower than 3.5 ng/mL was higher in cases (23.8