What does a high PSA mean? What the number says and does not say

You open the lab sheet and next to PSA you see a “high” flag or a red number. For most men the first thought is a single word. This article aims to make that thought a little more precise: what PSA is, what a high result means, and what happens next.

What is PSA?

It is a protein made by the prostate, and a small amount of it is in the blood of every man. The NHS says the test is used to investigate prostate conditions, including cancer and benign enlargement. MedlinePlus gives three reasons it is requested: optional screening, investigating symptoms (painful, slow or frequent urination, blood in the urine or semen, pelvic and back pain) and monitoring known conditions.

The EAU puts the key point this way: PSA is “organ-specific” but not “cancer-specific.” In other words, the prostate makes it whether it is healthy, enlarged, inflamed or cancerous.

What raises PSA?

The NHS says a high PSA does not mean you definitely have cancer. Benign prostate enlargement and a recent urinary infection raise it. MedlinePlus adds prostate inflammation, some medicines and ejaculation. The EAU widens the list:

• Infections can raise PSA very high and sometimes take up to a year to come down.
• Acute urinary retention has a moderate effect.
• A prostate biopsy in the last month; so delay the test by at least a month.
• A rectal examination does not change PSA.
• Medicines that shrink the prostate roughly halve PSA, so it has to be adjusted. If you take such medicines, be sure to tell your doctor.

To prepare, the NHS also says not to ejaculate, exercise or cycle for 48 hours before the test, and to wait 4 to 6 weeks after a urinary infection. The details are in the test preparation guide.

What number counts as “high”?

There is no simple answer. MedlinePlus says there is no single defined normal or abnormal PSA number. The EAU also writes that there is no agreed standard for defining an abnormal PSA. The most common threshold used in screening is 3 ng/mL, and the EAU says that with this threshold, 16.5 percent of invited men become “positive.” In men referred for assessment, a threshold of 4 ng/mL had a sensitivity of 0.93 and a specificity of only 0.20. In plain terms: this threshold catches most cancers, but it also labels many people as “high” who do not have cancer.

The number also changes from one test to another: the EAU says within-person variation is about fifteen percent up or down and differs by up to about five percent between labs. That is why it recommends repeating in the same lab, with the same method, under the same conditions.

What happens after a high result?

The NHS says that if the result is high, they first repeat the test. If it stays high, the doctor may raise referral for a biopsy and an MRI. For a PSA between 3 and 10, the EAU recommends repeating the test before any other work-up, and if the examination is not suspicious, about four weeks later.

For a man with no symptoms whose PSA is between 3 and 20, the EAU recommends that a prostate MRI help decide whether a biopsy is needed. The EAU also gives figures: at one MRI threshold, about 30 percent of biopsies are avoided and about 11 percent of more significant cancers are missed; at a stricter threshold, about 59 percent of biopsies are avoided and about 28 percent of those cancers are not seen. That is, every pathway involves a trade-off and should be weighed with your doctor.

MedlinePlus stresses that only a biopsy can diagnose cancer, and that the biopsy itself may cause bleeding, blood in the semen or urine, infection or difficulty urinating.

Screening: why “shared decision”?

Screening means testing a man who has no symptoms. Its benefits and harms are both real. The EAU writes that the Cochrane review (2018), with five trials and over 721,000 men, saw more diagnoses (ratio 1.23) but no better prostate-cancer-specific survival (0.96) and no better overall survival. On the other hand, in the ERSPC trial the benefit grew with longer follow-up: according to the EAU table, the number of patients who need treatment to prevent one death from prostate cancer fell from 48 at 9 years to 12 at 23 years. The same source says overtreatment of low-risk cancers cancels an important part of the benefit.

With this evidence, the EAU suggests an individual, risk-based strategy for a well-informed man with at least 15 years of life expectancy. Starting earlier is stated for higher-risk groups: from 50 as a rule, from 45 with a family history or of African ancestry, and from 40 in carriers of the BRCA2 gene. On the other hand, the NHS says routine testing is not offered to everyone unless a faulty BRCA2 gene has been found, and anyone can ask their doctor about it. These are European and UK guidelines, and your doctor also considers local factors.

A few practical points

• Do not measure PSA during an infection or soon after one.
• If you have several tests, keep all of them with their dates. The trend matters more than a single number.
• Talk to your doctor about a high result and do not guess. The repeat and the next decision are his or hers.
• Signs such as blood in the urine, being unable to pass urine or sudden pain do not wait for PSA; see urgent signs.
• For an enlarged prostate and urinary symptoms, read the prostate page.

A reminder

This article is for general information. The interpretation of your PSA depends on your age, history, medicines and other tests, and is for your doctor.