Alternative names, keywords

Prostate specific antigen

Samples required

Clotted blood (gold cap, 5 mL tube).

Test indications

Investigation and monitoring of prostatic disease.

Test information

Should not be used for population screening.

Factors affecting test performance/ results

In rare cases PSA isoforms exist which may be measured differently by different PSA tests.

Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration.

In rare cases, interference due to extremely high titres of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Reference range

< 40 years

< 1.40 µg/L

40 - 49 years

< 2.00 µg/L

50 - 59 years

< 3.89 µg/L

60 - 69 years

< 5.40 µg/L

≥ 70 years

< 6.22 µg/L

Source: Roche Cobas® Total PSA kit insert 04-2015, V12.0


The recommended referral value in men aged 50-69 is ≥ 3.0 ng/mL (≥ 3.0 µg/L).

NICE CKS Prostate Cancer [NICE, August 2018]
Public Health England (PHE) guidance: Prostate cancer risk management programme (PCRMP): benefits and risks of PSA testing [PHE, 2016]


Free PSA: The ratio of free PSA to total PSA is inversely related to the likelihood of prostate cancer. Depending on age, DRE and total PSA, a patient with a free:total PSA ratio of less than 0.15 (free PSA <15% of total) should generally be referred for further investigation. The higher the ratio the more likely it is to be BPH, however there is considerable overlap and clinical considerations should take precedence over fPSA when deciding on referral.

Turnaround time

One working day


Biochemistry (Automation)