Prostate ageing across the adult lifespan: population MRI evidence from 30 000 men

BACKGROUND: Prostate enlargement and lower urinary tract symptoms are common age-related conditions in men frequently encountered in primary care and geriatric medicine practice, yet population-level variation in prostate size and its biological drivers remain poorly defined due to limited scalable imaging. METHODS: We quantified prostate volume in 30 616 men using automated segmentation of whole-body MRI from the UK Biobank, establishing age-specific reference distributions across adulthood. RESULTS: Prostate volume increased continuously with age, and enlargement beyond commonly used clinical thresholds was already frequent in midlife. Multivariable analyses identified somatic (height), metabolic (body mass index and insulin-like growth factor 1), and endocrine (bioavailable testosterone) factors as independent correlates of prostate size, with stronger associations for height and bioavailable testosterone at older ages. Serum prostate-specific antigen scaled with MRI-derived prostate volume in an age-dependent manner, supporting biological validity. Larger prostates were associated with higher odds of clinically recorded lower urinary tract symptoms, with the strongest associations observed in midlife and attenuation in later life. CONCLUSIONS: These findings provide population-based MRI reference values and clarify the biological and symptomatic correlates of prostate ageing, illustrating how population-scale imaging can inform the evaluation of common age-related conditions.