Medical Articles · 6 min read
Understanding Your PSA Test
In brief
The PSA test measures prostate-specific antigen, a protein made by the prostate, in the blood. A raised PSA can be a sign of prostate cancer, but it is also commonly raised by benign prostate enlargement, inflammation or infection — so results are always interpreted in context.
Medically reviewed by Dr. Atip Chatsudthipong, MD on
Written by Editorial teamPublished Updated
What is PSA?
Prostate-specific antigen (PSA) is a protein produced by normal and cancerous prostate cells. Small amounts enter the bloodstream. The PSA test measures this level in nanograms per millilitre (ng/mL).
What is a normal PSA level?
There is no single "normal" PSA. Levels naturally rise with age and prostate size. Historically, 4.0 ng/mL was used as a threshold, but cancers can occur below it and many men above it do not have cancer. Urologists consider the PSA alongside age, prostate volume (PSA density), the change over time, family history and MRI findings.
What can raise PSA besides cancer?
- Benign prostate enlargement (BPH)
- Prostate inflammation or infection (prostatitis), or a urinary tract infection
- Recent ejaculation
- Recent urinary catheter, cystoscopy or prostate procedures
- Vigorous cycling, in some men
Medicines that lower PSA
5-alpha reductase inhibitors such as finasteride and dutasteride lower PSA by roughly half after several months. Tell your doctor if you take them so your result can be interpreted correctly.
My PSA is raised — what happens next?
- Repeat the test — often after a few weeks, avoiding ejaculation and vigorous exercise beforehand, and after any infection is treated.
- Clinical assessment — history, examination and review of medicines and family history.
- Prostate MRI — to look for areas suspicious for significant cancer.
- Biopsy if indicated — see Prostate biopsy.
Additional blood or urine tests (such as free PSA or other biomarkers) may help refine the decision about biopsy in some cases.
Should I have a PSA test?
PSA screening has benefits — finding significant cancers earlier — and drawbacks, including false alarms and the detection of slow-growing cancers that may never cause harm. Current guidance recommends an informed, shared decision with your doctor. Read more about prostate cancer screening.
Frequently asked questions
Do I need to fast before a PSA test?
No fasting is required for a PSA test. Avoid ejaculation and strenuous exercise such as cycling for about 48 hours beforehand, as they may temporarily raise PSA.
Can PSA go down again?
Yes. A PSA raised by infection, inflammation or recent activity often falls on repeat testing. That is why an abnormal result is usually repeated before further tests.
References
- 1.National Cancer Institute. Prostate-Specific Antigen (PSA) Test. (opens in a new tab)
- 2.Wei JT, et al. Early Detection of Prostate Cancer: AUA/SUO Guideline Part I — Prostate Cancer Screening. J Urol. 2023;210(1):46–53. (opens in a new tab)
- 3.Wei JT, et al. Early Detection of Prostate Cancer: AUA/SUO Guideline Part II — Considerations for a Prostate Biopsy. J Urol. 2023;210(1):54–63. (opens in a new tab)
- 4.European Association of Urology. EAU – EANM – ESTRO – ESUR – ISUP – SIOG Guidelines on Prostate Cancer. (opens in a new tab)
This information is for general education and does not replace a consultation with a qualified doctor. If you have severe symptoms, seek emergency care (in Thailand, call 1669). See our medical disclaimer.