From the Guidelines
Prior to taking a PSA (Prostate-Specific Antigen) blood test, patients should avoid ejaculation for 48 hours and vigorous exercise, especially cycling, for 2 days before the test, as these activities may cause prostate irritation and temporarily elevate PSA levels. According to the most recent and highest quality study, 1, patients should also inform their doctor about all medications they're taking, especially finasteride (Proscar, Propecia) or dutasteride (Avodart), which can lower PSA levels and affect interpretation. Additionally, patients should avoid scheduling the test within several days after a digital rectal exam (DRE) or any prostate manipulation procedures like cystoscopy or prostate biopsy, as these can significantly increase PSA levels. Some key points to consider before taking a PSA test include:
- Avoiding ejaculation for 48 hours before the test
- Avoiding vigorous exercise, especially cycling, for 2 days before the test
- Informing your doctor about all medications you're taking
- Avoiding scheduling the test within several days after a digital rectal exam (DRE) or any prostate manipulation procedures
- Not fasting before the test, as it is not necessary These precautions help ensure accurate results by avoiding factors that can artificially raise or lower PSA levels, which is important for proper screening and monitoring of prostate health conditions. It's also important to note that the benefits and harms of prostate cancer screening should be discussed with a doctor, as recommended by 1 and 1, and that the decision to screen should be based on individual risk factors and patient preferences. Furthermore, the National Comprehensive Cancer Network (NCCN) guidelines, 1, emphasize the importance of considering the limitations of PSA testing and the potential for false-positive results.
From the Research
Pre-PSA Lab Instructions
To prepare for a PSA lab test, it is essential to consider the impact of digital rectal examination (DRE) on PSA measurements.
- A study published in 2022 2 found that DRE can increase PSA levels, which may affect clinical decision-making.
- The study measured PSA levels in 74 participants before and after DRE, and found a significant increase in both total and free PSA levels after DRE.
- Another study published in 2024 3 compared the performance of DRE and PSA as screening tests for prostate cancer, and found that DRE has a low diagnostic value.
Digital Rectal Examination and PSA
- A 2007 study 4 found that finasteride improves the sensitivity of DRE for prostate cancer detection.
- A 2020 study 5 analyzed the value of DRE as a predictor of upgrading in a population of men with prostate cancer treated with active surveillance, and found that DRE can predict the presence of clinically significant prostate cancer.
- A 2018 study 6 investigated the effect of PSA on the association of DRE and clinically significant prostate cancer, and found that DRE demonstrates prognostic usefulness when PSA is greater than 3 ng/ml.
Instructions Prior to Taking PSA Lab
Based on the available evidence, it is recommended to:
- Avoid DRE immediately before PSA measurement, as it may increase PSA levels and affect clinical decision-making 2.
- Consider the use of DRE as an adjunct to PSA in the detection of clinically significant prostate cancer, particularly in men with elevated PSA levels 6.
- Be aware of the potential benefits and limitations of DRE in prostate cancer screening and detection 3, 4, 5.