Dr. Debasis Maity

What is serum PSA?

• Also called y-seminoprotein / HKK₃
• PSA (prostate specific antigen) is a glycoprotein, acts as serine protease / arginine protease.
• Molecular weight = 33 KD (contain 7% carbohydrate,240 amino acid).
• Found exclusively in epithelial cell of prostate.
• Functions: lyse the clot in ejaculate (liquefaction), release of spermatozoa from coagulum of semen.
• PSA gene (HKK₃₎ located in chromosome no 9
• Ectopic secretion of PSA seen in: breast CA, nodular breast tissue, breast milk, adrenal & renal CA, female serum.
• PSA is organ specific not cancer specific.
• Normal level of serum PSA: 1-4 ng/ml in male (50-80 yrs without prostatic disease)
• Serum PSA become detectable at puberty with ↑LH & testosterone hormone.
• In male without BPH - change in PSA = .04ng/ml/year
• In male with BPH - change in PSA = .07- .27 ng/ml/year (between 60-80 years of age)
• Ejaculation in male (>50years of age)- increases PSA; so repeat test after 48hrs sexual abstinence is helpful.
• Pt taking 5α reductase inhibitor but PSA increasing - indicate occult malignancy.
• 28% male with BPH = PSA value more than 4 ng/ml
• Statins decrease PSA by decreasing lipid
• PSA should be multiplied with 2 after 6 months of treatment with Dutasteride, with 2.3 after 2 years, with 2.5 after 7 years.
• PSAD(PSA density) = serum PSA / Prostate Volume; if ≥ .15,require prostate biopsy ( if PSA = 4-10ng/ml & DRE normal).
• PSA velocity – if > .75ng/ml/yr in male require prostate biopsy.
• 20% pt with PSA > 20ng/ml & 75% with PSA > 50ng/ml have lymph node metastasis.
• NCCN guidelines= bone scan to be done if -
  • PSA > 20ng/ml, or
  • Gleason’s score 8-10, or
  • clinical stage T3/ T4, or
  • clinical symptoms like bone pain,
  • Alkaline phosphatase.