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Laboratory Medicine

Test catalogue

Prostatic Specific Antigen, Free (Free PSA)

Test Name

Prostatic Specific Antigen, Free (Free PSA)

Gold Tube Specimen Type / Requirements

Container Type = Serum Gold Top Tube (SST)

Minimum Volume = 3 mL Serum

Tube must fill to at least ½ or greater of its vacuum capacity

Specimen Handling

Collection Instructions: Serum is the recommended sample. Serum collected with or without gel separator. Plasma samples should not be used. Ensure both samples and requisitions are lebeled properly. Recommend collecting prior to rectal exam or other action that may alter circulating PSA concentration.

Write your initials, date and time of collection on the collection label.

Laboratory Staff Instructions: Separate plasma as soon as possible. Turbid serum samples or samples containing particulate matter should be centrifuged prior to assay. Repeated freeze-thaw cycles have no effect on free PSA, total PSA, or % free PSA.

Transportation: Transport at room temperature ASAP. Place on ice if time of collection to time sample get to lab exceeds 2hrs

Stability: Stable refrigerated for 5 days and frozen at -20°C or colder for 3 months. Specimens to be held for longer than 5 months should be frozen at -70°C.

Sample Rejection Criteria: unlabeled or Not Sufficient Quantity Samples will be rejected

Required Documentation

Turnaround Time (TAT)

1 day

Test Utilization

Reference Value

otal < 4 µg/L : Prostate cancer unlikely and Free is not informative.

Total >10 µg/L: Prostate cancer likely and Free is not informative.

Total >=4 µg/L and <=10 µg/L: If Free/Total ratio >0.27 µg/L, chance of prostate cancer is about 10%.

< 0.17, chance of prostate cancer is about 50%.

Test Code




Testing Location

Referred Out – ON, Canada (ROICL02)

Other Information

Last Updated: June 06, 2019