Prostate-Specific Antigen (PSA) is a protein produced by the prostate gland, a small organ in men located below the bladder. A simple blood test measures PSA levels in the bloodstream. This test helps monitor prostate health and screen for potential issues.
Factors Influencing PSA Levels
Several non-disease related factors can cause temporary shifts in PSA levels. Ejaculation can lead to a short-term increase in PSA; avoiding sexual activity for 24-48 hours before a test is often recommended. Vigorous physical activity, especially cycling, can also cause temporary elevations.
Medical procedures involving the prostate, such as a digital rectal exam (DRE) or a prostate biopsy, are known to raise PSA levels. A prostate biopsy, for example, can cause substantial elevation, often requiring a delay of three to six weeks before a new PSA test. Prostate infections like prostatitis can also lead to a temporary increase in PSA. Certain medications, such as 5-alpha reductase inhibitors (e.g., finasteride or dutasteride), can reduce PSA levels by approximately 50% after about six months of continuous use.
Normal Daily and Short-Term PSA Variation
PSA levels are not constant; they exhibit natural biological variation within an individual. Research indicates that PSA measurements can fluctuate by 20% to 46% from one test to another, even daily or weekly. This fluctuation does not necessarily indicate a significant change in prostate health.
Beyond biological variation, minor differences in laboratory procedures, known as analytical variation, also contribute to observed changes in PSA readings. While analytical variation plays a role, biological variation is a more significant factor in short-term fluctuations. A single PSA reading provides only a snapshot of the moment it was taken. Small changes between tests, especially within the 20-46% range, are often not clinically meaningful.
What to Do About PSA Fluctuations
Interpreting PSA results requires a healthcare professional’s expertise, considering an individual’s complete medical history, overall health, and specific risk factors. Rather than focusing on a single high or fluctuating PSA reading, doctors emphasize tracking trends in PSA levels over time. A consistent rise or increasing values provide more meaningful information than isolated fluctuations.
If an initial PSA reading is unexpectedly high, especially if influencing factors were present, a doctor might recommend a repeat test after a few weeks. Discuss any questions or concerns about PSA results directly with a doctor. PSA is a screening tool, not a definitive diagnostic test; consistently elevated or rising levels may necessitate further evaluation.