A normal prostate-specific antigen (PSA) blood test level for a 70-year-old man typically ranges up to 4.5 ng/mL or 6.5 ng/mL, as baseline PSA thresholds increase naturally with advancing age due to normal prostate tissue enlargement, known as benign prostatic hyperplasia. However, urologists evaluate PSA levels within the broader context of prostate volume, free-to-total PSA ratios, and previous test velocity rather than relying on a rigid cutoff. Any rapid upward spike in PSA levels over a short twelve-month window warrants further diagnostic investigation, such as a multi-parametric MRI or targeted biopsy, regardless of whether the absolute value falls within standard age-adjusted reference ranges.