Thyroxine (T4), Free, Dialysis/Mass Spectrometry (Endocrine Sciences)

TEST: 501902
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CPT: 84439
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Synonyms

  • Free Thyroxine (T4) by Dialysis/Mass Spectrometry

Expected Turnaround Time

6 - 11 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

For more information, please view the literature below.

Free Thyroxine (FT4) by Dialysis and MS/MS

Thyroid Testing: Assessing Thyroid Disease in Your Patients

Specimen Requirements

Specimen

Serum or plasma

Volume

1 mL

Minimum Volume

0.5 mL; pediatric volume: 0.4 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube, gel-barrier tube, or lavender-top (EDTA) tube

Collection

Serum or plasma must be separated from cells within 45 minutes of venipuncture. Send serum or plasma in plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Storage Instructions

Freeze

Stability Requirements

Temperature

Period

Room temperature

2 days

Refrigerated

5 days

Frozen

453 days

Freeze/thaw cycles

Stable x3

Test Details

Methodology

Direct dialysis mass spectrometry; high-pressure liquid chromatography/mass spectrometry (HPLC/MS)

Reference Interval

See table.

Age

Range (ng/dL)

Premature (0 to 4 wk)

0.86−4.46

Newborn

0 to 2 wk

0.84−4.97

2 wk to 12 m

0.81−2.12

Children 1 to 11 y

0.65−1.9

Pubertal children and adults

0.8−1.7

Pregnant female

first trimester (0 to 13.3 wk)

0.65−1.4

second trimester (13.4 to 26.6 wk)

0.5−1.3

third trimester (>26.6 wk)

0.5−1.1

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
501902 Free T4 by Dialysis/Mass Spec 6892-4 501903 Free T4 by Dialysis/Mass Spec ng/dL 6892-4

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