Prostate-Specific Antigen

General

Synonym/Acronym:
PSA (total), Ultrasensitive PSA, prostate cancer antigen 3, Prostate Health Index and free PSA%, PSA velocity, 4Kscore.

Rationale
To assess prostate health and assist in diagnosis of disorders such as prostate cancer, inflammation, and benign hyperplasia and to evaluate effectiveness of medical and surgical therapeutic interventions.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: Electrochemiluminescent Immunoassay.

Conventional UnitsSI Units (Conventional Units × 1)
Total PSA assay (for use in initial screening)
0–4 ng/mL0–4 mcg/L
Ultrasensitive PSA assay (use in monitoring following radical prostatectomy for recurrence; assay has a much lower detectable limit—sensitivity of some assays is as low as less than 0.01 ng/mL)Less than 0.05 = absence of residual cancer
Prostate Cancer Antigen 3 (PCA3)Negative = Score less than 25
Prostate Health Index (PHI)PHI = p2PSA/(free PSA × total PSA)PHI less than 27% have a relatively low probability for prostate cancer; PHI between 27% and 55% predict a moderate probability for prostate cancer; and PHI greater than 55% have an increased risk for prostate cancer
Some guidelines recommend a lower range for Total PSA: 0–2.5 ng/mL.
There is usually no reportable range for free PSA; it is reported as a percentage of the total PSA.

Prostate Cancer in Men With a Slightly Elevated Total PSA (Between 4 and 10 ng/mL)
Free PSA (%) where Free PSA % = (free PSA/total PSA) × 100Probability of Developing Prostate Cancer
Greater than 30%8%–20%
21%–30%16%–19%
11%–20%20%–25%
1%–10%40%–50%
PSA velocity ng/mL
Change of less than 0.75/yrLow
Change of greater than 0.75/yrSuspicious
4K scoreLess than or equal to 7.5% = Low Risk for a diagnosis of aggressive prostate cancer (Gleason score 7 or higher) if a prostate biopsy were done

Critical Findings and Potential Interventions
N/A

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