T3, free

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Test Name:

T3, free

Synonyms:

Free triiodothyronine
FT3

Ordering Information:

Laboratory staff: If "T3" is written alone, order "T3, free" (FT3)

Collection Device/Tube Type:

1. EDM Base Lab: 5 mL blood - GOLD SST (gel)
2. CGY DSC: 4.5 mL blood - MINT LIHEP PST (gel)
3. NOTE: The preferred tube type at each testing site is acceptable at the alternate site

Submission Requirements:

1 mL serum or lithium heparin plasma

Frequency of Testing:

Daily

Reference Range:

Age	FT3 (pmol/L)
0 to < 30 days	4.2 – 13.0
30 days to < 1 year	5.1 – 8.6
1 year to < 14 years	4.4 – 8.1
14 years to < 18 years	3.5 – 7.4
≥ 18 years	3.0 – 6.5

Note: For interpretation of the test results in pregnancy, refer to the care pathway at Thyroid Function in Pregnancy

Comments:

Free T3 is ordered by the resulting location when progressive Thyroid stimulating hormone (TSH) testing is ordered, the TSH result is < 0.10 mIU/L and the free T4 result is low or normal

Refer to: Update to thyroid hormone reference intervals and to the progressive TSH algorithm (Lab Bulletin, 13 June 2022)

Last Reviewed:

04 May 2023

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