PSA

What is PSA?

PSA (prostate-specific antigen) is a protein produced almost entirely by the prostate gland. Small amounts leak into the bloodstream, where they can be measured, with results reported in nanograms per millilitre (ng/mL, numerically identical to µg/L). The standard test measures total PSA. Because PSA is made by prostate tissue in general — not only by disease — the amount in your blood broadly reflects the size and activity of your prostate, which is why the test is used only in men and tends to drift upward with age as the prostate naturally enlarges. PSA is a marker for monitoring, not a diagnostic test. A raised value tells you the prostate is releasing more protein than expected, not why. The most common reasons are entirely benign: an enlarged prostate (benign prostatic hyperplasia, very common from middle age onward), inflammation or infection of the prostate or bladder (prostatitis, urinary tract infection), and recent mechanical stimulation such as a prostate biopsy. Prostate cancer is one possible cause among several, and many cancers raise PSA only modestly — so PSA is read as a probability signal that guides further assessment, not as a yes/no answer. Because it is non-specific, PSA is always interpreted alongside your age, symptoms, prostate examination, and especially the trend across repeated measurements rather than from a single number in isolation. Testing is also a deliberate choice: because a result can lead to further investigation and sometimes overtreatment, guidelines recommend weighing the pros and cons with your clinician beforehand (shared decision-making).

Why is PSA relevant?

PSA matters because it is currently the most practical, widely available blood marker for keeping an eye on prostate health, and because the prostate is one of the most common sites of disease in men as they age. Used sensibly — with attention to your baseline and how it changes over time — it can flag a problem early enough to act on, while sparing you from over-reacting to a single number. There is no single universal 'normal' cut-off: PSA is a continuous scale on which a higher value means a greater likelihood of prostate cancer, with no threshold below which that likelihood is zero. In Dutch (and broader European) primary care, a total PSA of 3.0 ng/mL is the practical action threshold — at 3.0 ng/mL or above, and once a recent infection has been ruled out, men are generally referred for further evaluation, preferably to a centre with prostate MRI. The older, internationally cited figure of 4.0 ng/mL sits slightly higher; above it, and certainly above 10 ng/mL, concern increases. Some clinicians (more so outside Europe) also use age-adjusted upper limits that rise with each decade — broadly from around 2.5 ng/mL in your 40s to around 6.5 ng/mL in your 70s — but Dutch primary-care guidance does not use these age bands. Treat all of these numbers as orientation points, not thresholds for diagnosis. The value is greatest in context. The trend over time, how large the prostate is, your symptoms, and — in the grey zone between roughly 4 and 10 ng/mL — the proportion of free PSA all refine what a given number means. A modest, stable elevation in an older man with a large prostate reads very differently from a steadily rising value in someone younger. One caveat works the other way: because some aggressive tumours produce relatively little PSA, a low or normal value is reassuring but never a guarantee, which is why symptoms and examination still count.

PSA high or low — what it means

A single PSA reading is a snapshot and can be temporarily raised. By far the most important short-term cause is inflammation or infection of the prostate or urinary tract (prostatitis, a urinary tract infection); a recent prostate biopsy or urinary catheter can also lift the value for weeks. Ejaculation produces a smaller, short-lived rise that settles within about a day or two, so it is sensible to avoid ejaculation in the 48 hours before testing. A digital rectal examination and a long bike ride were long assumed to push PSA up substantially, but more recent evidence shows any effect is at most small and clinically minor. For a trustworthy baseline, avoid testing during or soon after an infection, and repeat an abnormal result — especially after prostatitis or a bladder infection — only after roughly 6 to 12 weeks before drawing conclusions. A high PSA far more often reflects something benign than cancer. The usual explanations are an enlarged prostate, prostate inflammation, or one of the temporary causes above. The higher the value and the faster the trend rises, the stronger the case for follow-up — which may mean a repeat test, a free-PSA measurement, imaging (prostate MRI), or assessment by a urologist. In current practice an MRI is done before any biopsy. A steadily rising trend is almost always more informative than one isolated high value. A low PSA is generally reassuring and points to low prostate activity, but it never fully rules out prostate disease — a minority of aggressive cancers produce little PSA — which is why symptoms and physical examination still count. Bear in mind, too, that medicines for an enlarged prostate (finasteride, dutasteride) roughly halve PSA after about six months of use; mention them so your clinician can correct the result accordingly (typically by doubling it). PSA is not something you lower as a goal in itself — it is a mirror, not a dial to turn. What matters is addressing the underlying cause: treating prostatitis, discussing symptoms of an enlarged prostate, and, where there is doubt or a rising trend, consulting a clinician promptly. This test is only relevant for men.

Educational information only — not medical advice. Consult a healthcare professional for clinical decisions.