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Lab Manual for Moffitt-Long and Mount Zion

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Free T4 (by dialysis)

Item Value
Approval req'd? Yes, contact Chemistry/Immunology Resident at x3-1438.
Available Stat? No
Test code FT4D
Test group Thyroid tests
Performed by Quest
Sendout? Yes
Method Equilibrium dialysis, RIA
Container type Red top preferred, Gold top acceptable
Amount to Collect 4 mL blood
Sample type Serum
Preferred volume 2 mL serum
Min. Volume 0.2 mL serum
Processing notes Refrigerate. Order Quest # 35167
Units ng/dL
Normal range
Prematures, 25-30 weeks, first week of life 0.5-3.3 ng/dL
Prematures, 31-36 weeks, first week of life 1.3-4.7 ng/dL
Cord blood, > 37 weeks 1.2-2.2 ng/dL
Birth-4 days 2.2-5.3 ng/dL
2 weeks-2 years 0.8-2.0 ng/dL
3-20 years 1.0-2.4 ng/dL
21-87 yr 0.8-2.7 ng/dL


Pregnancy:
First trimester 0.9-2.0 ng/dL
Second trimester 0.8-1.5 ng/dL
Third trimester 0.8-1.7 ng/dL
Synonyms tetraiodothyronine; thyroxine
Stability Room temperature 1 week, refrigerated 1 week, frozen at -20C 4 weeks
Turn around times Test performed Monday-Saturday. Turnaround time: 2-4 days.
Additional information Testing is only indicated if there is a descrepancy between the results for TSH and Free T4.
Medical Necessity? Yes. Click here for more information
LOINC code 6892-4
Last Updated 8/16/2011 10:42:38 AM
Entry Number 917

If you have additional questions regarding this test, please call: 415-353-1667

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