Free Triiodothyronine (FT3)
METHODOLOGY
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Electrochemiluminescence Immunoassay (ECLIA)
PERFORMED
Tuesday & Friday
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REPORTED
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2 days
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COLLECT
One 6 mL RT (Min: 4 mL RT)
TRANSPORT
1 mL refrigerated serum (Min: 0.5 mL)
STABILITY
Stored at 2 - 8°C until used; Stable if frozen at - 20°C
UNACCEPTABLE SPECIMENS
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Do not use heat-inactivated samples.
REFERENCE RANGE
1.9 – 5.1 pg/mL
CPT CODE
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84481
INFORMATION
Triiodothyronine (T3) is the biologically active form of thyroid hormone that is responsible for the effects of thyroid hormones on the various target organs. Only a small fraction of circulating T3 is derived from the thyroid. The T3 concentration in serum thus reflects the functional status of the peripheral tissues rather than the secretory performance of the thyroid. A reduction in the conversion of T4 to T3 results in a decrease in the T3 concentration. This occurs under the influence of drugs such as propranolol, glucocorticoids or amiodaron and in a variety of conditions associated with non-thyroidal illness (NTI).