RAISED PSA WORKUP
PSA is a glycoprotein enzyme secreted uniquely by prostatic ductal epithelial cells. It is prostate specific but not cancer specific. Its function is to liquefy semen.
The higher the value of PSA the more likely the existence of prostate cancer. The sensitivity and specificity of PSA depends on cutoff used. The positive predictive value of PSA is approximately 30% with a PSA cutoff of 4.1 ng/ml. PSA does not differentiate between indolent and aggressive disease but it can help to identify disease at an early stage.
Causes of raised PSA
- Prostate Cancer
- Prostatic infarction
- Instrumentation or IDC
- Prostate massage (not DRE)
- Acute Urinary Retention
A PSA test should always be interpreted with caution. A thorough history and physical exam should be performed to identify non-cancerous causes of raised PSA. A repeat or follow-up PSA is recommended to ensure a true elevation. The PSA level should be interpreted in reference to the patients age.
PSA thresholds should be age adjusted. The below values are based on 95% specificity (ie. 95th percentile of PSA for age) and is a guide for expected PSA levels per age.
0-2.5 ng/ml (median 0.6)
0-3.5 ng/ml (median 0.7)
0-4.5 ng/ml (median 1.3)
0-6.5 ng/ml (median 1.7)
RISK OF PROSTATE CANCER BASED ON PSA (PCPT trial)
The Urology Society of Australia and New Zealand (USANZ) recommend the following evidence-based recommendations on PSA-testing:
- Offer evidence-based decisional support to men considering whether or not to have a PSA test, including the opportunity to discuss the benefits and harms of PSA testing before making the decision.
- For men at average risk of prostate cancer who have been informed of the benefits and harms of testing and who decide to undergo regular testing for prostate cancer, offer PSA testing every 2 years from age 50 to age 69, and offer further investigation if total PSA is greater than 3.0 ng/mL.
What to do with raised PSA (above age specified limit) reading?
Dr Paffen recommends that GP’s can do the following prior to referral for raised PSA.
- Repeat PSA level (with free/total ratio) after 4 to 6 weeks, the PSA will drop again in 40% of people.
- Urine MCS to rule out UTI as a cause of raised PSA
- If a UTI is present a 4 week treatment with a sensitive antibiotic (avoid quinolones if possible) prior to repeating PSA testing
- A ultrasound KUB is also recommend to asses prostate volume, post-void residual and a screen for any upper tract pathology
Please refer to Dr Paffen if the following is present:
- If the digital rectal exam is abnormal
- If the PSA remains elevated
- if there is a raised PSA history
- PSA Density >0.15
- PSA Velocity>0.75 ng/ml/yr
- Free:Total ratio of <10%
Dr Paffen will further investigate patients with a full history, examination and MRI prostate prior to proceeding to prostate biopsy.