Prostate specific antigen (PSA)

A 60-year-old man presents with lower urinary tract symptoms and is offered a PSA test. According to NHS guidelines, which one of the following could interfere with the PSA level?

A. Vigorous exercise in the past 48 hours
B. Poorly controlled diabetes mellitus
C. Smoking in the past 48 hours
D. Current constipation
E. Drinking more than 4 units of alcohol in the past 48 hours

Answer:
A. Vigorous exercise in the past 48 hours

Discussion:

Prostate specific antigen (PSA) is a serine protease enzyme produced by normal and malignant prostate epithelial cells. It has become an important tumor marker but much controversy still exists regarding its usefulness as a screening tool.

The NHS Prostate Cancer Risk Management Programme (PCRMP) has published updated guidelines in 2009 on how to handle requests for PSA testing in asymptomatic men. A recent European trial (ERSPC) showed a statistically significant reduction in the rate of death prostate cancer by 20% in men aged 55 to 69 years but this was associated with a high risk of over-diagnosis and over-treatment. Having reviewed this and other data the National Screening Committee have decided not to introduce a prostate cancer screening programme yet but rather allow men to make an informed choice.

PSA levels may also be raised by: 
 benign prostatic hyperplasia (BPH)
 prostatitis and urinary tract infection (NICE recommend to postpone the PSA test for at least 1 month after treatment)
 ejaculation (ideally not in the previous 48 hours)
 vigorous exercise (ideally not in the previous 48 hours)
 urinary retention
 instrumentation of the urinary tract

Poor specificity and sensitivity 
 around 33% of men with a PSA of 4-10 ng/ml will be found to have prostate cancer. With a PSA of 10-20 ng/ml this rises to 60% of men
 around 20% with prostate cancer have a normal PSA
 various methods are used to try and add greater meaning to a PSA level including age-adjusted upper limits and monitoring change in PSA level with time (PSA velocity or PSA doubling time)

Age-adjusted upper limits for PSA were recommended by the PCRMP:
Age PSA level (ng/ml)
50-59 years ....3.0
60-69 years..... 4.0
> 70 years........5.0