Increase in Testosterone Levels and Improvement of Clinical Symptoms in Eugonadic men With a Prolactin-secreting Adenoma.

Objective: Testosterone concentrations, albeit rarely, may be in the normal range (>3.0 ng/mL) in men with a prolactin-secreting pituitary adenoma (PSPA-nt). The evolution of total, bioavailable testosterone, gonadotropin levels, and that of graded symptoms of testosterone deficiency (TD) are uncertain in these patients.

Design: Retrospective case-control longitudinal study at a tertiary referral center.

Methods: From 287 men, we selected 25 PSPA-nt men undergoing prolactin normalization (<20.0 ng/mL) during the follow-up. Graded symptoms of TD were investigated by structured interviews. Biochemical changes and TD symptoms were compared to those of a matched cohort of 61 men with pituitary neoplasms and normal testosterone levels (PA-nt).

Results: Baseline testosterone levels were similar between PSPA-nt and PA-nt subjects. The prevalence of specific and suggestive symptoms of TD was higher in PSPA-nt (20% and 68%) than in PAnt (3.3 and 29.5%; = .02 and = .0015, respectively). At the follow-up, total and bioavailable testosterone levels increased in PSPA-nt but not in PA-nt patients (Δ change: 1.28 ± 2.1 vs0.03 ± 1.5 ng/mL, + 0.33 ± 0.55 vs-0.26 ± 0.60 ng/mL; = .0028 and = .0088, respectively). LH and FSH levels also increased in PSPA-nt men ( < .05). Specific and suggestive, but not nonspecific symptoms of TD, improved only in PSPA-nt men ( < .05 for both). Baseline testosterone and LH were the strongest predictors of testosterone improvement in PSPA-nt patients.

Conclusion: Despite having normal testosterone levels at baseline, patients with PSPA-nt experience a relief of TD symptoms and an improvement of their pituitary-gonadal axis function following prolactin normalization, especially when baseline TT and LH levels are in the low-normal range.