Aims: Despite the prevalence of hypogonadism (testosterone deficiency [TD]) and widespread use of testosterone therapy (TTh), the effectiveness and safety of long-term testosterone use remains highly contested. Over the past 15 years, we have conducted a registry study of men with TD with a focus on several health outcomes associated with TTh.

Design: Observational patient disease registry study.

Materials and Methods: Noninterventional disease registry with prospective longitudinal data on a large sample of adult hypogonadal men (n = 858) who were treated in a single Urology Clinic. The registry evaluates men with symptomatic TD during a urological exam of patients who have not been previously treated with TTh. There were no inclusion/exclusion criteria. All hormone assays are carried out in a single laboratory. Standard-of-care treatment of each patient is the sole responsibility of the attending clinician. The registry data consist of comprehensive medical records and questionnaire data collected during patient visits. The registry has a dedicated statistician to ensure adequate statistical analyses of all outcome measures assessed.

Main Outcome Measures: We measured the following parameters: height, weight, waist circumference, hemoglobin, hematocrit, fasting glucose, glycated hemoglobin, insulin, systolic and diastolic blood pressure, heart rate, lipids (total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides), highly sensitive C-reactive protein, and total testosterone (T). We assessed quality of life, erectile and urinary function. Clinical parameters were measured two to four times a year. Data are analyzed in regular intervals.

Results: As of 2019, 858 men have been enrolled, of whom 85 patients exhibited primary hypogonadism, and the remaining 773 exhibited secondary or functional hypogonadism. Findings from this registry study on the benefit of TTh on anthropometric parameters, cardiometabolic function, diabetes, and prostate health have been reported.

Conclusions: This registry study has provided real-world clinical evidence and produced new important findings regarding the effectiveness and safety of long-term TTh in hypogonadal men.