Metabolic syndrome and male lower urinary tract symptoms

Historically, urologists regarded prostate enlargement as the sole cause for male bladder problems. Over time, subdivision of symptoms into storage, voiding and post-voiding symptoms raised awareness of the urinary tract fine-tuning associated with urine storage and voiding, and led to the umbrella term lower urinary tract symptoms (LUTS), which respects bladder and prostate function. While research goes on, it seems as if the more we know about urine storage and voiding, the more complicated it gets: different mechanism can mimic the same symptoms. Clinically, it remains ever the more challenging to understand the pathophysiological context of each patient. Metabolic syndrome (MetS), too, is an umbrella term. Metabolic changes caused by MetS pathophysiologically start with visceral adiposity. It leads to different changes in the signaling pathway including cytokines, elevated transmitters of inflammation, higher levels of free fatty acids (FFA), and adipokines, resulting in vasoconstriction, insulin resistance, impaired glucose uptake and high insulin secretion. Furthermore, MetS is thought to be associated with nephrolithiasis, BPH, LUTS, erectile dysfunction (ED), and infertility. This review aims at synthesizing interactions and consequences of LUTS with MetS.

On May 31^st, 2021, PubMed and Cochrane were searched with no language nor time restrictions, using the terms "Metabolic syndrome" and "male LUTS." A total of 252 publications were identified. Only papers that mentioned both terms either in their title or in their abstract were included. Hence, 120 papers were reviewed.

Many different findings cause LUTS, which are summarized in the EAU Guidelines on male non-neurogenic LUTS. These different symptoms belong to different phases of bladder function. Frequency, nocturia, urgency and incontinence are symptoms of the filling phase, while hesitancy, intermittency, weak or irregular stream, straining and terminal dribble belong to the voiding phase of the bladder. Post-voiding symptoms include post-void dribbling and sensation of incomplete voiding. Symptoms of any phase of bladder function impair quality of life, and are associated with ageing.

Inflammation links both umbrella terms, LUTS and MetS. Understanding the exact role of the different elements will not only help to better understand both findings, but also lead to more efficacious treatment, and hopefully, in the future, personalized medicine, by understanding each individual's driving mechanism for LUTS. Reducing inflammation is likely to help patients with MetS and LUTS; further research could therefore focus on how to manage inflammation.