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Free T4

Item Value
Test Update Information Effective March 19, 2013, the Free T4 assay changed from the Abbott Axsym to the Abbott Architect i2000 analyzer. NOTE new reference range.
Clinical Questions Does my patient have autoimmune thyroiditis?
Approval req'd? No
Available Stat? No
Test code FT4
Test group Thyroid tests
Performed by China Basin Chemistry
In House Availability Monday - Saturday (day shift)
Method Two step chemiluminescent Microparticle Immunoassay (Abbott Architect i2000)
Container type Gold top or Light Green top
Amount to Collect 1 mL blood
Sample type Serum or plasma
Preferred volume 0.5 mL serum or plasma
Min. Volume 0.25 mL serum or plasma
Processing notes Refrigerate
Units pmol/L
Normal range
Age Male (pmol/L) Female (pmol/L)
1-3 days 10-36 11-25
4-30 days 6-30 8-25
1-12 months 10-26 11-24
1-5 years 11-21 12-19
6-10 years 11-19 11-19
>10 years 10-18 10-18

Pediatric reference ranges adopted from Pediatric Reference Intervals seventh edition (Soldin, Steven J. et al) and Canadian Laboratory Initiative on Reference Interval Database (CALIPER) Clin Biochem 2009;42:885-991

Adult 95% reference range from the manufacturer (personal communication, Abbott Labs) was verified by running 148 non-autologous donor samples from subjects on no medications and neg. for TgAb and TPO Ab
Synonyms tetraiodothyronine; free thyroxine
Turn around times 0 to 2 days
CPT coding 84439
LOINC code 3024-7
Last Updated 6/20/2016 2:09:34 PM
Entry Number 916
Lab Procedure Link Click here for Procedure
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