Prostate Specific Antigen (PSA)

Last updated 20.02.13

 

Definition

- Glycorpotein produced soley by prostate gland

 

Indications

- Monitoring of known prostate Ca

-  Montiroing for recurrence

-  Watchful waiting: serial PSA every 6/12

- Dx of prostatitis

-  Sudden rise of PSA associated w pelvic discomfort & tender boggy prostate

-  Shoulde return to normal by 6 weeks

- Screening for prostate Ca

-  Routine screening not recommended

-  Men > 40yrs w family Hx of prostate Ca

-  Controversial if to test at >75yrs old unless for monitoring

-  More sensitive if combined with DRE (PR)

 

Features

-  Protein produced by prostate

-  Liquifies semen in ejaculate

-  Present serum of men in low levels

-  Tissue specific but NOT cancer specific

-  Not diagnostic

-  Medicare funding for yearly PSA unless monitoring

-  Needs to be combined with findings on DRE (PR)

 

Procedure

-  Venepuncture

-  Not within 24hrs of ejaculation or bike riding

 

Results

-  Antiandrogens may lower results (alpha blockers do not)

-  Unexpected rise when performing serial PSAs in low risk men repeat in 1-3 months

-  Serum PSA

-  N < 4ng/ml

-  Radical prostatectomy or postive response to radiotherapy levels should fall then remain at 0

-   If not 0 then either note all gland removed, recurrence of cancer or metastasis

-  Does not exclude prostate Ca

-  4-10

-  Suspicious of prostate Ca consider TRUS +/- Bx

-  Prostatitis, instrumentation (urinary), BPH, UTI

-  Recent ejaculation, bike riding

-  >10: prostate Ca

-  DRE (PR) does not raise PSA singicantly in normal prostates

-  In context of Dx prostate Ca

-  <4: 65% chance prostate only effected

-  4-10: 50%

-  10-20: 35%

-  >20: 20% or less

-  Ratio Free to Total PSA

-  < 25%: prostate Ca

-  Lower ratios higher risk

-  Used to reduce biopsies when PSA 4-10 ng/ml

-  Total & free PSA levels elevate post ejaculation

-  Return to normal within 24 hrs

 

 

 

References

 

AFP Vol. 40, No. 7, july 2011: Prostate Specific Antigen, Tom Brett

Red Book 2012