Type of test Blood
Normal findings
0-2.5 ng/mL is low
2.6-10 ng/mL is slightly to moderately elevated
10-19.9 ng/mL is moderately elevated
≥ 20 ng/mL is significantly elevated
Test explanation and related physiology
PSA is elevated in patients with prostate diseases (e.g., cancer, infection, and benign hypertrophy). PSA can be detected in all men; however, levels can be greatly increased in patients with prostate cancer. The higher the levels, the greater the tumor bur den. The PSA assay is also a sensitive test for monitoring response to therapy. Significant elevation in PSA subsequently indicates the recurrence of prostatic cancer.
There is considerable controversy regarding the use of PSA screening among asymptomatic men. Many professionals do not recommend the routine use of PSA screening in men of any age. Approximately 80% of PSA screening testing is falsely positive. A positive screening test result may trigger more aggressive and costly testing. It is important to be aware that some patients with early prostate cancer will not have elevated levels of PSA. PSA levels also may be minimally elevated in patients with benign prostatic hypertrophy (BPH) and prostatitis. In an effort to increase the accuracy of PSA testing, other measures of PSA or prostate proteins can be used:
• PSA velocity: PSA velocity is the change in PSA levels over time. A sharp rise in the PSA level raises the suspicion of cancer and may indicate a fast-growing cancer.
• Age-adjusted PSA: Age is an important factor in increasing PSA levels.
• PSA density: PSA density considers the relationship of the PSA level to the size of the prostate.
• Free: Free (protein unbound) PSA is a more accurate test for screening.
• Prostate-specific proteins: Prostate proteins (prostatic-specific membrane antigen or early prostate cancer antigen [EPCA]) may represent improved markers for prostate cancer.
• Prostate cancer–specific biomarkers: The most commonly tested marker is prostate cancer gene 3 (PCA3). Other genetic markers tested include GOLPH2, SPINK1, and TMPRSS2-ERG. These biomarkers are more specific to cancer and can indicate the risk that a prostate biopsy will show cancer.
• PSA isoforms: These isoforms can further increase the specificity of PSA to identify prostate cancer. The p2PSA is particularly specific.
• Prostate Health Index (phi): This is particularly helpful for patients whose total PSA is between 4 and 10 ng/mL. This is a formula that is calculated as follows:
Phi = p2PSA / free PSA X total PSA2
Calculating phi can reduce the number of unnecessary pros tate biopsies by 30%.
• Mi-Prostate Score (MiPS) combines the serum PSA with TMPRSS2-ERG and PCA3 in the urine. MiPS is used to predict a patient’s risk for having prostate cancer detected by standard biopsy. The test also predicts the patient’s risk for having potentially aggressive prostate cancer (Gleason score > 6).
• The 4Kscore test is a measurement of four prostate-specific kallikreins in the blood (total PSA [prostate-specific antigen], free PSA, intact PSA, and human kallikrein 2 [hK2]) together with clinical information in an algorithm that calculates an individual patient’s percentage risk of having an aggressive form of prostate cancer.
• Genomic prostate assay (p. 455, genomic testing), when used with commonly used pathology markers, can be used to indicate the likely clinical course of a known prostate cancer. Oncotypedx and Promark testing are commonly used tests. A low score is indicative of a less aggressive cancer for which observation alone may be reasonable. A high score indicates a more aggressive cancer that should be treated with aggressive intervention such as surgery or radiation.
Interfering factors
• Rectal examinations may elevate PSA levels. The PSA specimen should be drawn before rectal examination of the prostate or several hours afterward.
• Prostatic manipulation by biopsy or transurethral resection of the prostate (TURP) may elevate PSA levels. The test should be done before surgery or 6 weeks afterward.
• Ejaculation within 24 hours of blood testing is associated with elevated PSA levels.
• Recent urinary tract infection or prostatitis can cause elevations of PSA for as long as 6 weeks.
* Diethylstilbestrol (DES) and finasteride (Propecia, Proscar) cause decreased levels of PSA by about 50%.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: no
• Blood tube commonly used: red
• MiPS requires collection of the first 20 to 30 mL of voided urine after a digital rectal examination.
• The use of the percent-free PSA demands strict sample handling that is not required with the total PSA. Check for specific guidelines.
Abnormal findings
Increased levels
- Prostate cancer
- Benign prostatic hypertrophy
- Prostatitis
