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Test Code 0212902 Prostate Specific Antigen (PSA), Total and Free, Serum

Methodology

Chemiluminescent microparticle immunoassay (CMIA)
 

Performing Laboratory

Alomere Health Hospital Laboratory

Specimen Requirements

Specimen Type: Serum only

Collection Container/Tube: Gold (gel separator) or Red (plain)

Specimen Volume: 2.0 mL

Specimen Minimum Volume: 0.2 mL

Collection Instructions:

1. Allow serum tubes to clot completely. This may take up to 30 minutes.

2. Remove sample from cells by pipetting.

 

Reject Due To:

Plasma submitted

Specimen Transport Temperature

For Free PSA - Centrifuge and separate off cells within 3 hours

Within 48 hours:  Refrigerated (when centrifuged and separated off cells)

>48 hours:  Frozen

 

Reference Values

The total PSA range of 4.0 to 10.0 ng/mL has been described as a diagnostic "gray zone," in which the free PSA:total PSA ratio helps to determine the relative risk of prostate cancer (see table). Therefore, some urologists recommend using the free PSA:total ratio to help select which men should undergo biopsy. However, even a negative result of prostate biopsy does not rule-out prostate cancer. Up to 20% of men with negative biopsy results have subsequently been found to have cancer.

Our reference laboratory, Mayo Medical Laboratories, uses the following criteria:

 

Based on free PSA:total PSA ratio: the percent probability of finding prostate cancer on a needle biopsy by age in years:

Free PSA:total PSA ratio

50-59 years

60-69 years

70 years and older

≤0.10

49%

58%

65%

0.11-0.18

27%

34%

41%

0.19-0.25

18%

24%

30%

>0.25

9%

12%

16%

 

This testing method is a chemiluminescent microparticle immunoassay (CMIA) using the Alinity PSA Free and PSA Total assays.

Values obtained with different assay methods or kits may be different and cannot be used interchangeably. Test results cannot be interpreted as absolute evidence for the presence or absence of malignant disease.

Day(s) Test Set Up

Monday through Friday

Test Classification and CPT Coding

84153 - PSA. Total

84154 - PSA, Free