Thyroxine, Free, By Dialysis and HPLC Tandem Mass Spectrometry

TEST: 501902
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CPT: 84439
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Synonyms

Free Thyroxine (T4) by Dialysis/Mass Spectrometry

Expected Turnaround Time

4 - 6 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.

Specimen Requirements

Specimen

Serum or plasma

Volume

1 mL

Minimum Volume

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

Container

Serum: Red-top tube Plasma: Lavender-top (EDTA) tube

Collection

Separate serum or plasma within one hour; transfer into a plastic transport tube.

Storage Instructions

Ship refrigerated with cool pack or frozen on dry ice.

Test Details

Methodology

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

Reference Interval

Age Range (ng/dL) 1 - 11y 0.65 - 1.9 Pubertal Children and Adults Range (ng/dL) Males 0.8 - 1.7 Females 0.8 - 1.7 Pregnant Females Range (ng/dL) 1st trimester (0-13.3 wks) 0.65 - 1.4 2nd trimester (13.4-26.6 wks) 0.5 - 1.3 3rd trimester (>26.6 wks) 0.5 - 1.1