The Prostate-Specific Antigen (PSA) test is a blood test that measures the level of a protein, PSA, which is produced by both normal and cancerous cells within the prostate gland. Elevated levels of this protein in the bloodstream may indicate the presence of prostate cancer or other benign prostate conditions. The results of this simple blood draw provide medical professionals with an important data point for initiating further discussion and potential diagnostic steps regarding prostate health.
Does the PSA Test Require Fasting?
The PSA test does not typically require any dietary restrictions. The level of prostate-specific antigen in the blood is not significantly affected by what you eat or drink before the blood draw. Therefore, you can maintain your normal eating habits and drink water on the day of your test.
A patient should always confirm preparation instructions with the ordering physician or laboratory. This is because the PSA test is often conducted alongside other routine blood work that may require a fasting period, such as a cholesterol panel or a glucose test. Unless specifically instructed otherwise for a combination of tests, food and non-alcoholic beverages do not interfere with the accuracy of the PSA measurement.
Essential Preparation Steps for Accurate Results
While food and drink are generally not a concern, several physical activities and medical situations can cause a temporary and misleading elevation of PSA levels. To ensure the most accurate reading, patients are advised to avoid ejaculation for at least 48 hours prior to the blood test.
Vigorous exercise can also transiently increase the PSA value, particularly activities that place direct pressure on the prostate gland. Men should avoid strenuous physical activity, such as long-distance cycling or spin classes, for about 48 hours before the scheduled blood test. Avoiding these activities helps prevent mechanical irritation of the prostate that could temporarily release more PSA into the bloodstream.
Recent medical procedures involving the prostate require a waiting period before a PSA test. A digital rectal exam (DRE) is generally performed after the blood is drawn, as manipulation of the gland can cause a minor, temporary spike in the reading. More invasive procedures, such as a prostate biopsy or the recent use of a urinary catheter, significantly raise PSA levels and require a much longer waiting period, sometimes up to six weeks, to allow the levels to normalize.
Medications can also alter PSA levels and must be discussed with a doctor before testing. Drugs known as 5-alpha reductase inhibitors, like finasteride or dutasteride, are prescribed for conditions such as benign prostatic hyperplasia (BPH) or hair loss. These medications can artificially lower the PSA result by as much as 50 percent. Informing the physician about these drugs is necessary so they can properly interpret the result.
Interpreting PSA Test Levels
The result of a PSA test is reported in nanograms of PSA per milliliter of blood (ng/mL). While a PSA level below 4.0 ng/mL has historically been considered within the normal range, the level considered concerning varies significantly by age. For example, a PSA score greater than 2.5 ng/mL may be considered abnormal for men in their 40s and 50s, whereas a level higher than 4.0 ng/mL may raise concern for a man in his 60s.
An elevated PSA level does not automatically indicate the presence of cancer. Many common, non-cancerous conditions can cause the prostate to produce and release more of the protein into the blood. These benign causes include benign prostatic hyperplasia (BPH), the non-cancerous enlargement of the prostate that occurs as men age.
Infections or inflammation of the prostate, known as prostatitis, or a urinary tract infection (UTI) can also lead to a temporary elevation of PSA. If an elevated reading is detected, the doctor will consider these factors and may recommend a repeat test after the condition has cleared. Levels over 10.0 ng/mL are generally considered risky and significantly increase the probability of a prostate cancer diagnosis.
To refine the interpretation of a borderline or rising result, physicians may utilize additional metrics. PSA velocity tracks the rate of change in PSA over time, helping distinguish a slow, benign rise from a more rapid, potentially cancerous one. Furthermore, the ratio of free PSA to total PSA can be helpful, as a lower percentage of free PSA in the blood is often observed in men with prostate cancer. Further testing, such as a biopsy, is the only way to confirm cancer.
Prostate Cancer Screening Recommendations
Shared decision-making is emphasized regarding prostate cancer screening. This means a man should discuss the potential benefits and risks of the PSA test with his healthcare provider before deciding to proceed. The discussion should take into account the patient’s individual health status and life expectancy.
For men at average risk of prostate cancer, the discussion about starting screening typically begins around age 50. Screening may be recommended earlier for high-risk individuals, such as African American men or those with a strong family history. A strong family history means a father or brother was diagnosed with prostate cancer before age 65. For these groups, screening may begin as early as age 40 or 45.