In the context of BPH-related LUTS, PSA is commonly used beyond its accepted role as a cancer screening tool.54 PSA is produced by both benign and cancer cells in the prostate with its concentration influenced by volume and inflammation, thus making it a tool for assessing disease severity and predicting progression.55 PSA may be a good approximation for men without prostate cancer to aid in identifying LUTS/BPH. PSA performs reasonably well compared with planimetric transrectal ultrasound (TRUS) and better than DRE in estimating whether prostate volume is greater or smaller than 30, 40, or 50 cc.56 PSA elevation should be interpreted in clinical context with consideration of prostate cancer evaluation, when appropriate. Readily available adjuncts (e.g., PSA density and % free PSA) may help contextualize PSA values relative to prostate volume, and prostate multiparametric magnetic resonance imaging (mpMRI) can be considered when concern for clinically significant cancer persists before using PSA primarily as a surrogate for BPH severity. After engaging in shared decision-making with the patient, clinicians may obtain a PSA at initial evaluation for LUTS if there was no prior PSA obtained within the last year, a urinalysis shows no infection, and the patient is <80 years of age. If DRE reveals an abnormal nodule, a PSA should be obtained even if a PSA was obtained in the past. The role of PSA in predicting whether LUTS/BPH will worsen over time has been studied to show that a large baseline prostate volume and a high serum PSA level are the predominant risk factors for developing AUR.57, 58 In the placebo group of controlled studies, baseline serum PSA level and to a lesser extent prostate volume, consistently predict the risk of AUR and BPH-related surgery.59 Baseline serum PSA and/or prostate volume are useful tools to aid clinicians and decision makers in predicting the risk of BPH-related outcomes and choosing therapy for BPH.60 PSA also has a role in guiding treatment selection. PSA density could provide a variable for estimating BPH volume and may eventually improve selection of patients for 5-ARI treatment.61 A 5-ARI is best used in a prostate volume >30 cc and PSA >1.5 ng/mL, as is the combination therapy of an AB and 5-ARI.62 It also is a measure of effectiveness of intended treatment as “50% rule” applies to the PSA reduction after 3-6 months of 5-ARI treatment63, 64 or reduction in PSA to a new baseline after ablative surgical therapy to remove tissue for LUTS/BPH management.65