Unless specifically requested by a doctor, fasting is typically not required prior to a prostate-specific antigen, or PSA, blood test, according to Lab Tests Online. If fasting is required, patients must consume no food or drinks, except water, for a time period prior to the lab test, explains Quest Diagnostics.
Because it's easier to draw blood from people who are adequately hydrated, it's important to drink plenty of water while fasting prior to a blood test, according to Quest Diagnostics. Patients should continue taking all medications during the fasting period, unless otherwise directed by a doctor. When fasting is required, it's best to schedule the blood test first thing in the morning to minimize the amount of time without food. If desired, patients may bring a snack with them to eat after the blood test is complete.
Although patients usually don't need to fast before a PSA blood test, other preparation is required, according to Lab Tests Online. Because ejaculation sometimes raises PSA levels, it's best for patients to avoid ejaculating for 24 hours prior to the blood test. Patients should have a PSA test done before a doctor performs a digital rectal exam and before a prostate biopsy. Patients with a recent prostate biopsy should wait several weeks before having a PSA blood test.