The Prostate-Specific Antigen (PSA) test is a common blood screening tool used to assess prostate health, primarily serving as an early indicator of potential prostate problems. The usefulness of this test relies on obtaining an accurate baseline measurement of the protein circulating in the bloodstream. Many non-disease factors can temporarily influence PSA levels, leading to the common question of whether recent sexual activity affects the results. Understanding these variables is important for ensuring the test provides reliable information for patient care.
Understanding the Role of PSA
Prostate-Specific Antigen is a protein produced predominantly by the cells of the prostate gland, located beneath the bladder. Its primary function is to help liquefy semen following ejaculation, aiding in sperm mobility. While most PSA is contained within the prostate or semen, a small amount naturally leaks into the bloodstream.
The PSA blood test measures the concentration of this protein in the blood, typically reported in nanograms per milliliter (ng/mL). Elevated levels of PSA can signal a number of different prostate conditions, not exclusively cancer. Non-cancerous causes of a high PSA reading include an enlarged prostate, known as benign prostatic hyperplasia (BPH), or inflammation of the prostate, called prostatitis.
Because the PSA level can be affected by various factors, a single elevated reading is generally not enough for a diagnosis. Instead, doctors often look for a trend of rising PSA levels over time or consider the result in combination with other diagnostic tools. The test acts as an indicator, prompting further investigation when a result suggests a change in prostate health.
The Direct Link Between Ejaculation and PSA Levels
Ejaculation causes a temporary rise in the amount of PSA found in the bloodstream. The prostate gland is a muscular organ that contracts forcefully during ejaculation to expel semen. These strong contractions physically squeeze the prostate tissue. This mechanical action forces a greater amount of PSA protein out of the gland and into the general circulation.
Studies have documented that serum PSA concentration significantly increases following ejaculation in a majority of men. The rise is typically noticeable within the first hour after the event. The spike can be up to 0.8 ng/mL above the baseline level, which is particularly significant for men whose baseline PSA levels are already in a borderline range (e.g., 2.5 to 4.0 ng/mL). The elevated PSA level usually begins to return to its pre-ejaculation baseline within 24 hours, though a full return can take up to 48 hours.
Preparing for the PSA Test
Given the temporary impact of ejaculation on PSA concentration, healthcare providers recommend sexual abstinence before the blood draw. The National Comprehensive Cancer Network (NCCN) guidelines suggest men abstain from ejaculation for at least 48 hours prior to the PSA test. Observing this two-day window helps eliminate the spike caused by prostatic contractions, ensuring the measured value is reliable.
Patients must also avoid other physical activities that can similarly put pressure on the prostate and cause a temporary rise in PSA. Vigorous exercise, especially activities like long-distance cycling or heavy weightlifting, should also be avoided for 48 hours before the test. The mechanical pressure on the perineum from a bicycle seat, for example, can mimic the effect of prostatic manipulation.
Several non-sexual and non-exercise factors must also be considered for accurate preparation, as they can significantly affect PSA levels. These factors include recent physical manipulation of the prostate, such as a digital rectal exam (DRE) or a prostate biopsy. Prostatitis (infection or inflammation of the prostate) or a urinary tract infection also causes a substantial rise, requiring the test to be delayed until the condition resolves. Certain medications, like 5-alpha reductase inhibitors used to treat BPH, can also lower PSA levels, which doctors must account for when interpreting results.