A High PSA Result: What It Means, and What to Do Next

最終更新日： 8月 25, 2026

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PSA appears in most health-check packages sold to men over a certain age, which means a great many men receive a raised result having never actually decided to be screened for prostate cancer. They arrive in clinic frightened, holding one number.

That number is not a diagnosis. It is a starting point, and quite often it turns out to mean very little.

• 泌尿器センター バンコク病院 タイ オンライン予約 02-310-3009 bhquro@bdms.co.th
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There is no single number that means cancer

A figure of 4 ng/mL is widely used as a cut-off and is worth understanding rather than trusting. An earlier version of this article called it the current standard definition of an elevated PSA, which is tidier than reality.

• Most men above 4 do not have cancer. The great majority of raised results have a benign explanation.
• Cancer does occur below 4, so a result under the line is reassuring rather than conclusive.
• What is normal rises with age and with the size of the prostate — a large gland makes more PSA simply by being large.

PSA is made by prostate tissue, not by cancer specifically. Anything that enlarges, inflames or disturbs the prostate raises it.

What raises PSA, in rough order of how often

• Benign prostatic enlargement. By a wide margin the commonest reason, and the one the earlier version of this article left out of its list altogether.
• Prostatitis or a urinary infection. These can push PSA up dramatically, and it can take weeks to settle afterwards — testing during or just after an infection is one of the commonest causes of a frightening result.
• Recent instrumentation — a catheter, a cystoscopy, or a previous biopsy.
• Urinary retention.
• Recent ejaculation — abstain for about 48 hours before the test.
• Vigorous cycling in particular, in the day or two beforehand.

And one thing that lowers it

Finasteride and dutasteride roughly halve the PSA. If you take either — usually for an enlarged prostate or for hair loss — the number on your report understates your true level and has to be interpreted accordingly. This was mentioned only in passing at the foot of the earlier version, and it belongs here: a man on one of these drugs with a PSA that looks reassuring may not be reassuring at all. Tell whoever orders the test.

The first step is usually to repeat it

PSA varies in the same man from week to week, and a proportion of raised results simply come back normal when checked again — particularly where there has been an infection, a catheter or a recent procedure, in which case the repeat is left several weeks.

Alongside the repeat comes a physical examination of the prostate, which gives information the blood test cannot. Nothing irreversible should follow from a single raised reading, and a man who is offered a biopsy on the strength of one number without a repeat is entitled to ask why.

What is used to decide whether a biopsy is needed

• The trend over time. A PSA climbing steadily across several readings means more than any single value. The earlier version of this article gave a rise of 0.75 ng/mL per year as a threshold suggesting cancer; that figure has been removed, because rate of change is no longer accepted as a reason for biopsy on its own. It informs the picture rather than deciding it.
• Free PSA ratio, which can help where the total PSA sits in the moderately raised range with a normal examination. The earlier version stated that a ratio below 10% indicates about a 50% cancer risk, without saying that this applies to that specific range — a qualifier that changes the meaning considerably.
• MRI of the prostate, performed before any biopsy, and now the most useful of the three.

What the MRI figure actually means

The earlier version credited MRI with over 90% cancer detection rate. That is a misreading of what the number describes, and it has been corrected.

The strength of prostate MRI is the reverse of detection: when it shows nothing suspicious, significant cancer is unlikely to be present — reliable enough that a reassuring scan, in the right clinical context, is a legitimate reason not to biopsy at all. That is genuinely valuable, and it is not the same as finding 90% of cancers. MRI misses some, its accuracy depends on the scanner and on who reads it, and a suspicious area still has to be sampled to know what it is.

If a biopsy is needed

The earlier version described transrectal ultrasound-guided biopsy as the definitive diagnostic test. Practice has moved on, and this page now agrees with the rest of the site: the MRI images are fused with live ultrasound so the needle is aimed rather than scattered, and the needle is passed through the skin of the perineum rather than through the rectal wall, which is what makes serious infection uncommon. See MRIフュージョン経会陰前立腺生検, 、および what to expect afterwards.

Two things are worth knowing before you agree to one. A negative biopsy does not entirely close the question, since it samples part of the gland. And finding cancer does not automatically mean treating it — a proportion of prostate cancers grow slowly enough that monitoring is the right management, and the grade reported by the pathologist drives what follows. If treatment is needed, see the treatment pathway.

And if you have not yet had a PSA test and are deciding whether to, that is its own question — should I have a PSA test. The link on this page previously pointed to an address that no longer exists.

Symptoms that need attention rather than a repeat blood test

In an emergency in Thailand, call 1669.

• Inability to pass urine with a painful full bladder — same-day treatment.
• Fever with pain low down or on passing urine.
• Visible blood in the urine or semen.
• New bone pain in the back, hips or ribs, or unexplained weight loss.
• New leg weakness, numbness, or difficulty controlling the bladder or bowel in a man known to have prostate cancer — this needs emergency assessment.

Frequently Asked Questions About a High PSA

PSA値が高いと前立腺がんということですか？

No. Most raised results have a benign explanation — benign enlargement of the prostate above all, then prostatitis or urinary infection, recent instrumentation, retention, recent ejaculation or vigorous cycling. PSA is made by prostate tissue generally, not by cancer specifically.

Is 4 ng/mL the line between normal and abnormal?

It is a widely used cut-off rather than a boundary between health and disease. Most men above it do not have cancer, some cancers occur below it, and what counts as normal rises with age and with prostate size.

What happens first after a raised result?

Usually the test is repeated, with an examination of the prostate — and left several weeks if there has been an infection, a catheter or a procedure. A proportion of raised readings return to normal on repeat. Nothing irreversible should follow from a single number.

How should I prepare for a PSA test?

Abstain from ejaculation for about 48 hours and avoid vigorous cycling for a couple of days beforehand. Tell your doctor about any recent urinary infection, catheter or urological procedure, and — importantly — if you take finasteride or dutasteride, which roughly halve the reading.

My MRI was clear. Can I skip the biopsy?

Often, yes. A prostate MRI showing nothing suspicious makes significant cancer unlikely, and in the right clinical context following the PSA rather than proceeding to biopsy is a reasonable choice. It is not an absolute guarantee — MRI misses some cancers and its accuracy depends on the scanner and the radiologist — so it is a decision made together rather than an automatic discharge.

相談の手続きをする

Dr. Soarawee Weerasopone sees patients at バンコク病院本部 そしてチョンブリー県のサミティベート・シーラチャ病院にて 088-022-1445. Bring every previous PSA result with its date rather than only the latest one — the trend is worth more than the number — along with a list of your medicines.

バンコク病院の遠隔医療は、来院が困難な患者様（海外からの患者様を含みます）を対象にご利用いただけます。泌尿器科宛てに事前にメールでご手配ください。 bhquro@bdms.co.th. サミティベート・シラチャは対面診療のみです。料金に関するお問い合わせは当ウェブサイトではなく、病院にお問い合わせください。.

免責事項 この記事の内容は、バンコク病院本社（Bangkok Hospital Headquarters）の認定泌尿器科医であるソラウィー・ウィーラソポン医師（Dr. Soarawee Weerasopone）が執筆および監修したものであり、教育目的のみを意図しています。これは医学的なアドバイス、診断、または個別の処方ではなく、個人的なメッセージングチャンネルやソーシャルメディアを通じてアドバイス、診断、処方が行われることはありません。ソラウィー医師は公開のソーシャルメディアアカウントを運営していません。彼の名前で個人的な相談を提供しているアカウントはすべて詐欺です。タイで緊急事態が発生した場合は、以下にお電話ください。 1669.