The Prostate-Specific Antigen (PSA) test is a blood analysis that measures a protein produced by the prostate gland. PSA is made by both healthy and malignant prostate cells. The test serves as a screening tool, indicating prostate health rather than providing a definitive diagnosis of disease. An elevated, or “abnormal,” PSA result signals an increased production of this protein, prompting the need for further medical evaluation. However, receiving an elevated result does not confirm cancer, as many non-cancerous conditions can also cause the level to rise.
Interpreting the PSA Test Results
The concept of a single “normal” PSA level is limited, as the threshold for concern varies based on individual factors, particularly age. While 4.0 nanograms per milliliter (ng/mL) was traditionally a benchmark, medical professionals now use age-specific reference ranges because PSA levels naturally increase as men get older. For example, a level above 2.5 ng/mL might be considered elevated for a man in his 40s, but a man in his 70s might have an acceptable limit up to 6.5 ng/mL.
Clinicians use advanced metrics beyond a single number to assess the potential risk associated with an elevated finding. PSA velocity measures how quickly the PSA level rises over time; a rapid increase, often defined as greater than 0.75 ng/mL per year, raises suspicion. PSA density divides the total PSA level by the volume of the prostate gland, determined via imaging. Since a larger gland produces more PSA, a high density ratio suggests the elevation is disproportionate to the gland’s size, potentially indicating greater concern.
A single elevated reading rarely dictates the entire diagnostic path, and medical professionals often look for a consistent trend over multiple tests. The risk of finding cancer increases directly with the PSA value; for example, a PSA between 4 and 10 ng/mL has about a 25% chance of indicating prostate cancer. When the PSA level exceeds 10 ng/mL, the probability of cancer being present rises significantly.
Common Non-Cancerous Reasons for Elevation
The most frequent non-cancerous cause of an elevated PSA is Benign Prostatic Hyperplasia (BPH), which is an enlargement of the prostate gland. As the prostate tissue increases in size, it generates and releases more PSA into the bloodstream. This condition is common as men age, and larger prostate volumes are directly associated with higher PSA concentrations.
Prostatitis, inflammation or infection of the prostate, is another common cause that can lead to a temporary PSA increase. Both acute and chronic forms of inflammation can elevate protein levels by disrupting the prostate tissue barrier, allowing more PSA to leak into the blood. A urinary tract infection (UTI) can also irritate the prostate, leading to a rise in PSA that typically resolves once the infection is treated.
Several transient factors can temporarily cause an elevated PSA result. Recent ejaculation can cause a variable increase in PSA, so patients are generally advised to abstain from sexual activity for 24 to 48 hours before the test. Vigorous physical activity, especially cycling, which puts direct pressure on the perineum, may also cause a transient spike. Any physical manipulation of the gland, such as a recent prostate biopsy or the insertion of a catheter, causes trauma that can artificially inflate the PSA level for several weeks.
The Diagnostic Pathway Following an Abnormal Result
Following an initial abnormal PSA test, the physician typically performs a Digital Rectal Exam (DRE) to feel the prostate gland for hard or irregular areas. Although the DRE has limitations, an abnormal finding combined with a raised PSA level increases the suspicion of cancer. The next step often involves repeating the PSA test after a short waiting period, usually a few weeks, especially if transient factors like infection or recent sexual activity were possible.
If the repeat PSA remains elevated, or if the DRE is suspicious, the physician will likely recommend advanced imaging, such as a multiparametric Magnetic Resonance Imaging (mpMRI) of the prostate. The MRI provides detailed images of the prostate and surrounding tissues, helping identify and categorize suspicious areas before considering a biopsy. Radiologists use a standardized scoring system, such as PI-RADS, to rate the likelihood of clinically significant cancer being present on a scale of 1 to 5.
The results of the mpMRI heavily influence the decision to proceed to a prostate biopsy, which remains the only way to definitively diagnose cancer. If the MRI shows a highly suspicious lesion, a targeted biopsy is performed using the MRI images to guide the needle directly into the abnormal area. If the MRI is negative but the PSA remains high, a systematic 12-core biopsy may still be recommended, as the MRI can occasionally miss cancers. This decision weighs the patient’s overall health, life expectancy, and the potential benefits and risks of the procedure.