Association between testosterone levels and RigiScan parameters of patients with erectile dysfunction.

Background: It is difficult to diagnose hypogonadism because of the lack of objective assessments of erectile dysfunction (ED), which is caused by hypogonadism.

Aim: To provide a new approach for diagnosing hypogonadism, this study evaluated the efficacy of nocturnal penile tumescence and rigidity (NPTR) testing with RigiScan for patients with ED with and without hypogonadism.

Methods: From June 2021 to February 2023, 133 patients with ED (62 with hypogonadism and 71 without) underwent NPTR testing at the Department of Andrology. A detailed history of all participants was obtained. All participants also underwent a physical examination, sex hormone testing, and ultrasound examination of the cavernous vessels of the penis.

Outcomes: Patient characteristics, sex hormone serum levels, and RigiScan Plus data of NPTR testing of patients with ED were obtained and evaluated.

Results: Between the groups, there were no significant differences in age, body mass index, or erectile function score or in the prevalence of smoking, drinking, diabetes, hypertension, and hyperlipidemia. RigiScan data revealed differences in erection episodes per night, average event rigidity, erection durations, and percentage of tumescence greater than baseline, which were significantly lower in the testosterone-deficient group than in the normal testosterone group. The average event rigidity of the tip displayed the largest area under the curve value, with a sensitivity of 67.6%, a specificity of 85.5%, and a cutoff value of 52.50.

Clinical implications: Our findings may allow appropriate patients to receive testosterone replacement therapy, which has been shown to be an effective treatment for hypogonadism.

Strengths and limitations: This is the first study of its kind to perform a comprehensive review of the association between hypogonadism and RigiScan parameters. This study was limited by its small sample size.

Conclusion: RigiScan parameters of patients with ED and testosterone deficiency were significantly lower than those of patients with normal testosterone; therefore, RigiScan is useful for the differential diagnosis of patients with ED caused by hypogonadism.