Prostate Specific Antigen, Free

Alternative Names/Synonyms	Free PSA
Laboratory	Core Laboratory & Transfusion Medicine
Sub-section	Biochemistry
Specimen Type	Blood
Test Code	See Prostate Specific Antigen, Total for information.

Clinical Significance

Distinguishing prostate cancer from benign prostatic conditions in patients with borderline or moderately increased Prostate Specific Antigen, Total.

Specimen Requirements (Sample Type)

Serum, Plasma

Specimen Requirements (Volume (mL))

0.5 mL

Specimen Requirements (Tube Type)

Serum (Gold SST)
Plasma (Light Green PST)
Collection Containers – Tube Types

Collection Requirements

Blood Collection Instructions

Sample Stability

Room Temperature: N/A

Fridge: 5 days @ 2-8°C

Freezer: 3 months @ -20°C

Cause for Rejection

Specimen Acceptability and Transport Guidance

Instrument, Methodology

Roche cobas e 602, immunoassay

Test Availability

24 hours a day, 7 days a week

STAT Turnaround Time

1 hour

Routine Turnaround Time

3 hours

Reference Ranges

Free PSA / Total PSA Ratio > 0.27, chance of prostatic cancer is about 10%.
Free PSA / Total PSA Ratio < 0.17, chance of prostatic cancer is about 50%.

In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.

Laboratory Contact Information

416-586-4800 extension 4688

Ordering Practices

Free PSA is reflexed only when Prostate Specific Antigen, Total falls within 4 - 10 ug/L.