Austin Pathology

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Prostate Specific Antigen - Free

Alternate Names
Free PSA, FPSA, PSA - Free, PSA - (Free-to-Bound)
Ordering Information

Free PSA may be helpful in some situations where the Total PSA is equivocal. Requests for free PSA will only be performed if the Total PSA is within Medicare guidelines.

 

Please note assay change details:

From 24/02/20, free PSA assayed on Beckman-Coulter DxI using the Hybritech calibration.

Compared to our previous assay (Roche Cobas), FreePSA and Free:Total PSA results are similar but in some individuals this relationship between the two assays will be significantly different.

Therefore, it is recommended that numerical results from different assays are not directly compared and that longitudinal monitoring of results should be conducted using the same platform.

Please note reference interval for this assay remains the same.
Laboratory
Biochemistry
Specimen
Blood
Container
Serum tube (gold cap OR red cap w. yellow insert)
Minimum Adult Volume
5mL
Minimum Paediatric Volume
None
Frequency
Monday - Friday
Reference Interval

Total PSA and Free PSA will be measured and Free PSA expressed as a Free:Total (%):

Free PSA ÷ Total PSA x 100

 

Interpretative assistance for Free:Total PSA ratio

Free:Total PSA (%) Probability of Malignancy (for men with non suspicious DRE, and regardless of age)
< 10  56%
10 - 15 25%
15 - 20 20%
20 - 25 16%
> 25 8 %

Source: Beckman-Coulter

These PDF documents can be downloaded for your reference

Order of Draw (PDF)

Swab Collection Guide (PDF)

Pre-Transfusion Specimen Requirements (PDF)

Requirements for Pathology Service (PDF)

Test Code
PSAF
Container ID
S, SP, LH, LHP
Additional (Storage) Instructions

Samples for Free PSA are only stable at room temp or 4°C for 24 hours, so serum for testing must be frozen if not tested within the 24 hours.
Laboratory Notes

All free PSA requests must have Total PSA measured first.
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Austin Hospital Studley Road
Heidelberg, VIC 3084
Phone:9496-3100
Fax: 03 9496 5803

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