What is a normal PSA level?

There is no single normal PSA level. The National Cancer Institute is explicit: "there is no single threshold that distinguishes a normal versus an abnormal PSA result. This is in part because there is no specific PSA level that means that someone has prostate cancer."

The number most often quoted is 4.0. NCI notes that "a PSA level above 4.0 ng/mL is considered abnormal and may result in a recommendation for prostate biopsy." Treat that as a doorway, not a verdict. Some doctors use a higher cutoff for older men and a lower one for younger men, because PSA drifts up with age on its own.

Why one number cannot settle it

The reason sits in the definition. NCI describes PSA as "a protein produced by normal, as well as malignant, cells of the prostate gland." Healthy prostate tissue makes it too. So the blood test measures how much prostate activity there is, not whether any of it is cancer. Anything that irritates or enlarges the gland pushes the number up.

The usual culprits are not cancer at all. Benign prostatic hyperplasia, an enlarged prostate that becomes common with age, raises PSA. So does prostatitis, meaning inflammation of the prostate. NCI also lists "vigorous exercise (such as cycling) and ejaculation" as temporary causes. And "an infection or inflammation of the prostate or having had a recent prostate biopsy can cause PSA levels to be raised for a month or two."

Two common medicines push the number the other way. NCI notes that finasteride and dutasteride, both used for an enlarged prostate or hair loss, lower PSA. A man taking one of them can have a reading that looks reassuring while sitting on top of a higher true value.

What a raised result actually predicts

This is the part worth memorizing before the phone call. NCI reports that "about 6%–7% of men have a false-positive PSA test on any given screening round, and only about 25% of men who have a biopsy due to an elevated PSA level are found to have prostate cancer."

Read that second figure again. Three out of four men who go on to biopsy because of a high PSA turn out not to have prostate cancer. A raised PSA is a reason to look further. It is not a diagnosis, and treating it as one causes a lot of unnecessary fear.

Where screening guidance stands

The US Preventive Services Task Force splits its advice by age. For men aged 55 to 69, whether to screen is an individual decision to be made after discussing the potential benefits and harms with a clinician. For men aged 70 and over, NCI reports that PSA-based screening "is not recommended."

Three practical things

Timing changes the result. Avoid ejaculation and a long bike ride in the days before a PSA test, and reschedule if you have a urinary infection or have had a recent prostate biopsy.

Make sure whoever reads the result knows about finasteride or dutasteride, since the number needs interpreting differently.

And if a single reading comes back high, ask whether repeating it is sensible before anything else is booked. One raised value in isolation says much less than a pattern does.