PSA - Prostate Specific Antigen
(Biochemistry)
Investigation : PSA - Prostate Specific Antigen
Specimen type : Serum Gel
Spec container : Serum Gel 
Volume required : 5 ml
Reference range : < 4.0 ug/l
Turnaround : <48 hours

Generally, it is not necessary to repeat a PSA measurement within 1 month of a previous result.

PSA - Prostate Specific Antigen - R Weston Feb 2011 v 1.3

PSA is a serum marker for prostate cancer. It is produced by normal prostate cells and can be elevated by prostate cancer, benign prostatic hypertrophy (BPH), infection, inflammation (prostatitis), instrumentation such as catheterisation and other benign conditions.

Prostate Cancer and PSA testing

PSA testing has three main roles:

PSA testing should be offered to men with lower urinary tract symptoms suggestive of BPH for two reasons:

Asymptomatic men requesting PSA testing should be counselled before the test for the following reasons:

Reference Range for PSA

There is no absolute PSA value which is diagnostic of prostate cancer. Generally as men age PSA will increase, thought mainly to be related to development of BPH. As PSA rises so does the relative risk of prostate cancer. Below is the age related reference range for PSA. A level above the reference range for the patientsí age warrants referral via the 2 week cancer rule to a urologist. There is no widely accepted reference range for patients over the age of eighty, and it is recommended that PSA is only performed in those patients with a clinical suspicion of locally advanced or metastatic disease.

Age (years)
PSA (ng/ml)
40 - 49
0 - 2.5
50 - 59
0 - 3.5
60 - 69
0 - 4.5
70 - 79
0 - 6.5

In the presence of an elevated PSA and suspected contributing cause such as infection the test should be repeated after appropriate treatment before referral to a urologist.

Prostate Cancer and DRE

DRE is a useful adjunct to PSA testing however as an independent variable, PSA concentration is a better predictor of prostate cancer than DRE. In rare cases of poorly differentiated prostate cancer a DRE may be grossly abnormal despite a normal PSA level. Studies have demonstrated that a simple DRE is unlikely to significantly effect the PSA result.

Effect of drugs on PSA

Finasteride and Dutasteride are both 5-α reductase inhibitors used to treat prostatic hypertrophy, reduces PSA by approximately 50%.

PSA screening

PSA screening is a contentious issue and currently there is no nationally adopted screening for prostate cancer. Three large randomised, controlled trials are currently evaluating PSA screening for prostate cancer: the European Randomised Study of Screening for Prostate Cancer (ERSPC), the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial (US) and the UK-based Prostate Testing for Cancer and Treatment (ProtecT) study. This does not however mean that aymptomatic men should have PSA testing declined if a patient requests it.

PSA Velocity

This simply refers to the rate of rise of PSA over time. To calculate the velocity the PSA should be monitored on at least three occasions at six monthly intervals. A change in PSA concentration of >0.75 ng/ml per year is more likely to indicate prostate cancer than BPH. The usefulness of PSA velocity in those with a PSA concentration >10 ng/ml is unknown.

AUH service users: new PSA units ug/L are equivalent to previous (ng/mL).

ICE requesting info:ICE panel nameICE page nameColumnComment\Advice
Chem / Haem
Endo & Oncology
3
only available on male patients


Back

Laboratory Services Home Page