At a glance
| Analyte | Free triiodothyronine |
|---|---|
| Also called | Free T3, Free triiodothyronine |
| Method | Competitive chemiluminescence immunoassay |
| Sample type | Serum, Plasma |
| Panel | Thyroid |
| Discipline | CLIA immunoassay |
| Brand | Mindray |
What FT3 measures
Triiodothyronine is the more biologically potent thyroid hormone, and most of it is produced by conversion from thyroxine in peripheral tissue rather than secreted directly by the thyroid. FT3 measures the unbound fraction. Its clinical value is concentrated in hyperthyroidism, where it is often raised earlier and more markedly than FT4, and where a particular presentation exists in which the TSH is suppressed and the FT3 raised while the FT4 remains within the reference interval. In hypothyroidism it adds much less, because peripheral conversion is maintained until the disease is advanced, which is why FT3 is generally added to a thyroid request rather than included in it by default.
How Philippine laboratories run it
Ordered as the third assay in a thyroid panel, most often when a suppressed TSH has already raised the question of an overactive thyroid, so its volume sits below both TSH and FT4 in almost every Philippine laboratory. Framar sees that ratio consistently in delivery records, and it is worth respecting when planning: over-ordering FT3 to match TSH volume leaves a laboratory holding reagent it will not use before expiry. Endocrinology clinics managing patients on antithyroid therapy account for most repeat testing.
Analyzers it runs on
Calibrator, controls and companion tests
Delivered with the control material it is verified against and the rest of the thyroid panel, on the same schedule as FT3.
Storage and handling
Refrigerated, upright, and not frozen.
Buying FT3 in the Philippines
FT3 is supplied for the CL-2600i and CL-900i. We deliver it with Thyroid Control and TSH, because a run held up waiting on a separate order costs the same shift a stock-out does. Delivery is scheduled against your monthly FT3 count, so the bench is not rationing tests in the last week of the month. How we plan clia immunoassay supply.
Questions about FT3
When is FT3 worth adding to a thyroid panel?
Principally when hyperthyroidism is the question. FT3 often rises earlier and further than FT4 in an overactive thyroid, and there is a recognised pattern in which TSH is suppressed and FT3 raised while FT4 remains normal. In suspected hypothyroidism it adds relatively little, because peripheral conversion is preserved until the disease is well advanced.
Order FT3
Tell us your monthly FT3 volume and we will quote a supply schedule for CL-2600i. We reply within one business day.
Request a quotation