PSA
testing: sensitivity and specificity- With a cut-off of 4 ng/ ml, the sensitivity of PSA for prostatic cancer is 46% specificity is 91 % and positive predictive value is 32.
- PSA picks up 75% of organ-confined cancers, compared with 56% detected by rectal examination alone.
- A man with a PSA of 4-10 and normal rectal examination has a 25% chance of prostate cancer, most likely to be of low grade.
- Levels above 12 ng/ml are suggestive of cancer.
- PSA Is normal in 20% of cases of prostatic cancer.
- PSA is mildly raised in 30-50% of men with BPH.
- Most labs increase the normal cut-off level with age.
- PSA is altered by
- Rectal examination raises PSA by about 0.4 ng/ml
- Finasteride lowers PSA on average by 50%
- Transrectal biopsy and TURP elevate PSA for 2-3 weeks
- Prostatitis and prostatic infarction raise PSA to high levels
- Red blood cell changes