Chemical Pathology


Total Prostate Specific Antigen (PSA) is used in the diagnosis and monitoring of therapy/management of patients with prostate cancer. The assay measures free and complexed PSA in blood.

While PSA has been shown to be raised in prostatic cancer, it may not always detect the disease in its early stages. Normal results can occur in intracapsular prostate cancer.

There is a high incidence of false positive results in screening for prostatic cancer and PSA may be raised in the following non-malignant conditions:

  • Benign prostatic hypertrophy (BPH)
  • Acute and chronic prostatitis
  • Urinary retention
  • A transurethral resection of the prostate (TURP) and prostatic biopsy
  • Prostate massage (digital rectal examination)
  • Ejaculation

The test should NOT be used for non-prostatic disease.

The half life in blood is 2.5 days.

Men seeking a PSA test must be fully informed before requesting the test. For more information please see the Cancer Research UK page on the PSA test.

Sample requirements

  • If the patient is on high dose biotin therapy (>5 mg/day), collect the sample at least 8 hours after the last dose
  • Requests for PSA always require a fresh sample. The test cannot be added to a sample already in the laboratory because of the risk of carryover

5 ml of blood taken into a narrow gold top gel tube (or rust top for the Acute Unit)

5ml gold tube

Take the blood sample before any digital rectal examination.


Samples should be sent at ambient temperature to the laboratory. If unavoidable, samples can be refrigerated overnight.

Required information

Include any relevant clinical details; if the test is for diagnosis or follow-up; if any other examination or surgery of the prostate has occurred within 5 days of the test; if the patient is receiving any current medical treatment for prostatic disease.

Turnaround time

Samples are run throughout the day and night as they arrive. The turnaround time is less than 48 hours.

Reference ranges

Age Reference range Units
<50 years <2.5 µg/L
50 - 59 years <3.5 µg/L
60 - 69 years <4.5 µg/L
>69 years <6.5 µg/L

Further information

To learn more about PSA, visit Lab Tests Online

For information on NHS screening for prostate cancer, visit NHS prostate cancer screening website

For information on the PSA test, visit Cancer Research UK

Page last updated: 09/11/2018