Functional causes of low testosterone predominate in contemporary Australian endocrine referral practice: a two centre experience across 5 years.

Abstract

Background: The epidemiology and outpatient management of low testosterone in Australian tertiary care remain poorly characterised. Rising testosterone prescription rates and evolving guidelines underscore the need to delineate contemporary referral patterns, diagnostic adherence, and therapeutic practice.

Methods: A retrospective review was undertaken of all new male patients assessed for low testosterone levels at Gold Coast University and Robina Hospitals between 2020 and 2024. Demographic, biochemical, and management data were extracted from the integrated electronic medical record. Continuous variables were analysed using the Kruskal-Wallis test, categorical variables using χ² or Fisher's exact test, and binary logistic regression identified predictors of testosterone replacement therapy (TRT) initiation and pituitary imaging.

Results: Among 294 consecutive referrals, functional low testosterone (43%) exceeded all pathological diagnostic categories combined individually. Obesity affected 65% of patients and obstructive sleep apnoea 28%, the latter highest in functional low testosterone (48%; p < 0.001). Two-thirds of referrals included two early-morning testosterone samples, pituitary imaging was performed in one-quarter of patients, with clinically actionable abnormalities identified in 4% of imaged men. TRT was prescribed in 25% of men, less often in functional than pathological forms (23% vs. 45%; OR 0.37, 95% CI 0.22-0.62; p < 0.001). Most patients were discharged after a median of three visits and six months' follow-up. Functional low testosterone was associated with a high burden of cardiometabolic and psychological comorbidity. Across the entire cohort, 31% reported previous androgen exposure.

Conclusions: Most men referred with low testosterone did not have structural hypothalamic-pituitary-testicular axis disease, supporting a clinical approach prioritising identification of metabolic and reversible contributors before testosterone therapy. Diagnostic completeness and adherence to guideline-recommended imaging vary, but testosterone prescribing generally aligns with current Endocrine Society of Australia (ESA) and Pharmaceutical Benefits Scheme (PBS) restrictions. These findings support the establishment of a dedicated andrology service integrating metabolic, reproductive, and psychological care to optimise assessment and outcomes in men with androgen deficiency.