At a glance
| Analyte | Free prostate-specific antigen |
|---|---|
| Also called | fPSA, Free PSA |
| Method | Two-site sandwich chemiluminescence immunoassay |
| Sample type | Serum, Plasma |
| Panel | Tumour marker |
| Discipline | CLIA immunoassay |
| Brand | Mindray |
What Free PSA measures
Prostate-specific antigen circulates in two forms: bound to plasma proteins and unbound. This assay measures the unbound portion, and it is not reported as a standalone figure because on its own it means very little. Its purpose is the ratio it forms with the total, since the proportion circulating free differs between benign and other prostate conditions, and that proportion adds discriminating information in the intermediate total range where the total alone leaves the question open. Both measurements must come from the same specimen for the ratio to be valid, and interpretation belongs to the requesting physician alongside examination and history.
How Philippine laboratories run it
Free PSA is ordered specifically in urology follow-up rather than included in general check-up packages, so its volume sits well below total PSA in Philippine laboratories and its requests arrive as a defined subset. The supply consequence is straightforward but easy to get wrong: the free assay is worthless without the total, so a laboratory that runs out of total PSA has lost both, while running out of free PSA alone costs only the ratio. Framar plans the two together with the volume difference built in rather than at parity.
Analyzers it runs on
Calibrator, controls and companion tests
Delivered with the rest of the tumour marker panel, on the same schedule as Free PSA.
Storage and handling
Refrigerated, upright, and not frozen.
Buying Free PSA in the Philippines
Free PSA is supplied for the CL-2600i and CL-900i. We deliver it with Total PSA, because a run held up waiting on a separate order costs the same shift a stock-out does. Delivery is scheduled against your monthly Free PSA count, so the bench is not rationing tests in the last week of the month. How we plan clia immunoassay supply.
Questions about Free PSA
Can free PSA be reported on its own?
It should not be. The free measurement carries information only as a proportion of the total, so a free PSA without a total from the same specimen is not interpretable. Laboratories offering it therefore run both on one sample and report the ratio, which also means the two reagents need to be stocked together rather than ordered independently.
Order Free PSA
Tell us your monthly Free PSA volume and we will quote a supply schedule for CL-2600i. We reply within one business day.
Request a quotation