Idiopathic hyperprolactinemia-associated hypogonadism in men presenting with normal testosterone levels

Hypogonadism, presenting with low libido, erectile dysfunction, and gynecomastia, frequently occurs in men with hyperprolactinemia, typically characterized by elevated serum prolactin, suppressed gonadotropins, and low testosterone. However, we identified a rare subset of patients who presented with normal testosterone levels, but whose clinical profiles were poorly defined.

A retrospective analysis of medical records was conducted on 23 men diagnosed with idiopathic hyperprolactinemia and normal testosterone levels between 01/07/2019 and 01/12/2024. Baseline clinical characteristics, hormone levels, pituitary gland dimensions (as measured by MRI-derived pituitary height), and responses to medical treatments (bromocriptine or cabergoline) were evaluated.

The mean age at diagnosis was 30.91 ± 7.66 years (range: 20-50). Mean serum prolactin at presentation was 38.22 ± 30.68 ng/mL (range: 20.00-170.93), and mean pituitary height was 6.40 ± 0.97 mm. Primary complaints at diagnosis included low libido, gynecomastia, impotence, and erectile dysfunction. Eighteen patients received bromocriptine, whereas five patients received cabergoline. After an average treatment duration of 7.83 ± 6.97 months (range: 1-29 months), prolactin levels normalized in all patients, pituitary height was significantly reduced to 4.39 ± 1.37 mm, and most patients reported notable clinical improvements, particularly in sexual function.

Idiopathic hyperprolactinemia-associated hypogonadism can occasionally present with normal testosterone levels, emphasizing the importance of clinical vigilance beyond standard hormonal assessments. Pituitary height reduction may serve as an important diagnostic marker and indicator of treatment effectiveness. Medical treatment, including bromocriptine or cabergoline, with a possible preference for cabergoline based on clinical considerations, can effectively normalize hormone levels and significantly improve clinical symptoms.