PSA blood test: what high PSA levels mean, normal range by age and free PSA

A PSA above the limit for your age means the prostate is leaking more PSA than usual, and the job is to work out why. In a man with urinary symptoms and a large gland on examination, BPH is the likeliest explanation, and PSA roughly tracks gland size (about 0.1 ng/mL per gram of benign tissue, so a 60 g prostate alone can produce a PSA of 4 to 6). In a man with pain, fever, burning on urination or a recent urinary infection, prostatitis is the likeliest explanation and can produce values of 10 to 50 ng/mL that fall back over six to eight weeks. In a man with neither, the question of cancer becomes more pressing.

The level and its context grade the concern. A PSA of 4 to 10 carries about a 25 percent chance of cancer, and of the cancers found about three-quarters are low or intermediate grade. Above 10 the chance exceeds 50 percent and the cancers are more often higher grade. A free PSA under 10 percent, a density above 0.15 ng/mL per cc, a rise of more than 0.75 ng/mL in a year confirmed on repeat, a firm nodule on rectal examination, a family history or BRCA mutation, and Black ancestry each increase the probability, and a multiparametric MRI showing a PI-RADS 4 or 5 lesion increases it considerably; a normal MRI (PI-RADS 1 or 2) lowers it enough that many men can avoid biopsy.

One raised value should not lead directly to a biopsy. Guidelines recommend repeating the PSA after a few weeks (after treating any infection and avoiding ejaculation and cycling for 48 hours), since about a quarter of raised values are normal on repeat. If it is still raised, the usual sequence is free PSA or another reflex marker, an MRI, and then a targeted biopsy if the MRI is suspicious. Transient rises after a catheter, cystoscopy, biopsy or acute urinary retention are expected and the test should wait six weeks.

Common causes

1. 1.

   Benign prostatic hyperplasia (BPH)

   The most common cause. The gland grows with age in most men and PSA rises about 0.1 ng/mL per gram of extra tissue, so a large benign prostate of 60 to 80 g can produce a PSA of 4 to 8. PSA density corrects for this.

2. 2.

   Prostatitis and urinary tract infection

   Acute bacterial prostatitis can push PSA to 20 to 50 ng/mL or more within days; chronic prostatitis and even asymptomatic inflammation found on biopsy raise it more modestly. Levels take 6 to 8 weeks to fall after treatment, so the test is repeated then.

3. 3.

   Prostate cancer

   Cancer disrupts the gland and releases roughly 10 times more PSA per gram than benign tissue; the risk is about 15 percent below 4 ng/mL, 25 percent at 4 to 10 and over 50 percent above 10. Some aggressive cancers make little PSA, so a normal value does not exclude it.

4. 4.

   Ejaculation within 48 hours

   Raises PSA by a small amount (up to about 0.4 to 0.8 ng/mL) for 24 to 48 hours in some men, enough to tip a borderline result over the line. Abstain for two days before the test.

5. 5.

   Prostate manipulation: catheter, cystoscopy, biopsy, acute retention

   A urinary catheter, a cystoscopy, a prostate biopsy or an episode of acute retention can raise PSA severalfold; wait at least 6 weeks after any of these. A digital rectal examination causes only a trivial rise and need not delay the test.

6. 6.

   Vigorous cycling and perineal trauma

   Long rides compress the perineum and prostate; studies are mixed, with small rises in some men. Avoid a long ride in the 48 hours before the test if a result will be borderline.

7. 7.

   Age

   PSA rises about 3 percent a year in healthy men, both from gland growth and from more leakage; this is why age-specific limits exist.

8. 8.

   Testosterone treatment

   Restoring testosterone in a hypogonadal man typically raises PSA by 0.3 to 0.5 ng/mL in the first year as the gland regains normal size; a rise of more than 1.4 ng/mL in a year or above 4.0 prompts urological review.

9. 9.

   Stopping finasteride or dutasteride

   These drugs roughly halve PSA; when they are stopped the level returns to its untreated value over several months, which can look like a sudden rise.

10. 10.

    Prostate infarction, stones and rare non-prostate sources

    Infarcts in a large gland and prostatic calculi cause transient rises. Tiny amounts of PSA come from periurethral glands and some breast and salivary tumours, but never enough to explain a clearly raised value in a man with a prostate.

Symptoms that can go with it

• Usually none; most raised PSAs are found on screening in men who feel well
• A weak or interrupted stream, hesitancy, straining, dribbling and incomplete emptying (BPH or any obstructing process)
• Getting up at night to urinate, frequency and urgency
• Burning on urination, fever, chills, pelvic or perineal pain and painful ejaculation with prostatitis
• Blood in the urine or semen, which always needs assessment
• Erectile dysfunction, which is common with BPH and prostatitis and occasionally with locally advanced cancer
• Bone pain (back, hips, ribs), weight loss, fatigue or leg swelling, which can indicate advanced prostate cancer and need prompt review

There is no lower limit of concern for PSA in a man who still has his prostate. A low or undetectable value means the gland is small, quiet and not inflamed, and in screening terms a low baseline is strongly reassuring: a PSA below 1.0 ng/mL at age 60 is associated with a 0.2 percent risk of dying from prostate cancer by 85, low enough that many guidelines allow screening to stop or the interval to stretch to several years. A PSA below 1.0 at age 45 to 50 similarly allows a longer interval between tests.

Some low values need interpreting. Finasteride and dutasteride, taken for BPH or hair loss, halve PSA within 6 to 12 months, so the measured value should be doubled to compare with the usual ranges; a rise from the lowest value on the drug is significant even if the absolute number is small. Obesity lowers PSA by 10 to 20 percent through dilution in a larger blood volume, which can mask a cancer slightly. Androgen deprivation therapy, low testosterone and anything that shrinks the gland lower PSA. After a radical prostatectomy PSA should be undetectable (below 0.1 ng/mL), and a confirmed rise to 0.2 or more is the definition of recurrence, so 'low' here is the goal, not a problem.

Common causes

1. 1.

   A small, healthy prostate

   Young men and men with small glands have PSA of 0.3 to 1.0 ng/mL; this is the expected result and carries a very low long-term cancer risk.

2. 2.

   Finasteride or dutasteride

   5-alpha reductase inhibitors shrink the gland and halve PSA by 6 to 12 months (and by about two-thirds after several years); double the result to interpret it and watch for any rise from the nadir.

3. 3.

   Obesity

   Larger plasma volume dilutes PSA by roughly 10 to 20 percent in men with a BMI over 35, and lower testosterone in obesity shrinks the gland; some clinicians adjust the threshold down slightly.

4. 4.

   Androgen deprivation therapy or low testosterone

   PSA production is androgen-dependent; castration-level testosterone drives PSA toward zero even when cancer is present, which is why PSA is tracked together with testosterone during treatment.

5. 5.

   After radical prostatectomy

   With the gland removed PSA should fall to undetectable within about 6 weeks; any confirmed value of 0.2 ng/mL or more indicates residual or recurrent cancer.

6. 6.

   Some medications

   Statins, thiazide diuretics, NSAIDs and acetaminophen are associated with slightly lower PSA (a few percent) in observational studies; the effect is too small to matter clinically but adds to the noise.

Symptoms that can go with it

• None; a low PSA does not cause symptoms
• Urinary symptoms with a low PSA still need assessment, since bladder, urethral and neurological causes do not raise PSA, and neither does a poorly differentiated cancer