At a glance
| Analyte | Total triiodothyronine |
|---|---|
| Also called | Total T3, Triiodothyronine |
| Method | Competitive chemiluminescence immunoassay |
| Sample type | Serum, Plasma |
| Panel | Thyroid |
| Discipline | CLIA immunoassay |
| Brand | Mindray |
What T3 measures
Total triiodothyronine measures the bound and free hormone together. Like total T4 it is affected by carrier protein concentration, so it shifts in pregnancy and with oestrogen therapy independently of thyroid function, and the free measurement is the more robust of the two for that reason. It retains a role in the assessment of an overactive thyroid, where T3 characteristically rises early, and it is part of the long-established three-test panel of T3, T4 and TSH that many clinicians continue to request as a unit. Interpretation depends on reading it against the TSH rather than against a reference interval alone.
How Philippine laboratories run it
The T3, T4 and TSH combination remains a familiar and frequently ordered panel in Philippine outpatient practice, particularly outside specialist endocrinology, and laboratories that carry only the free assays find themselves unable to fill a proportion of the requests that arrive. Volume sits below TSH and roughly alongside total T4, and the two totals should be planned together since they are generally requested as a pair. Where a laboratory offers both the total and free versions, expect the split to be driven by the referring clinic rather than by clinical guidance.
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 T3.
Storage and handling
Refrigerated, upright, and not frozen.
Buying T3 in the Philippines
T3 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 T3 count, so the bench is not rationing tests in the last week of the month. How we plan clia immunoassay supply.
Questions about T3
What is the difference between T3 and FT3?
T3 measures all the triiodothyronine in the sample, both the fraction bound to carrier proteins and the small free fraction. FT3 measures only the free portion, which is the part able to act on tissue. The free measurement is unaffected by changes in carrier proteins, which is why it is the more reliable of the two in pregnancy and in patients on oestrogen therapy.
Order T3
Tell us your monthly T3 volume and we will quote a supply schedule for CL-2600i. We reply within one business day.
Request a quotation