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Thyroxine, Free by Equilibrium Dialysis/HPLC-Tandem Mass Spectrometry
0093244
Ordering Recommendation

Not recommended for routine evaluation of thyroid disorders. Preferred test is Thyroxine, Free (Free FT4) (0070138).

Mnemonic
FT4 ED-TMS
Methodology
Quantitative Equilibrium Dialysis/High Performance Liquid Chromatography-Tandem Mass Spectrometry
Performed
Sun, Tue, Thu
Reported
2-5 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
 
Collect
Plain Red or Serum Separator Tube (SST). 
Specimen Preparation
Separate from cells or gel ASAP or within 2 hours of collection.  Transfer 2 mL serum to an ARUP Standard Transport Tube. (Min: 0.3 mL) 
Storage/Transport Temperature
Refrigerated. 
Unacceptable Conditions
Plasma. 
Remarks
 
Stability
After separation from cells: Ambient: 4 days; Refrigerated: 2 weeks; Frozen: 1 month 
Reference Interval
Effective May 16, 2011
Free Thyroxine ng/dL
AgeFemaleMale
25-30 weeks gestation0.5-3.3 ng/dL0.5-3.3 ng/dL
31-36 weeks gestation1.3-4.7 ng/dL1.3-4.7 ng/dL
Birth to 1 week2.2-5.3 ng/dL2.2-5.3 ng/dL
2-3 weeks0.9-4.0 ng/dL0.9-4.0 ng/dL
1-5 months1.1-2.2 ng/dL1.1-2.2 ng/dL
6 months-6 years1.4-2.7 ng/dL1.4-2.7 ng/dL
7 years-17 years1.1-2.0 ng/dL1.1-2.0 ng/dL
18 years and older1.1-2.4 ng/dL1.1-2.4 ng/dL
Pregnancy, 1st Trimester0.7-2.0 ng/dL
Pregnancy, 2nd Trimester0.7-2.1 ng/dL
Pregnancy, 3rd Trimester0.5-1.6 ng/dL

Interpretive Data


Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Note
Hotline History
N/A
CPT Code(s)
84439
Components
Component Test Code*Component Chart NameLOINC
0093244Free T4 by Equil Dialysis-TMS6892-4
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Direct Dialysis
  • FT4
  • T4, Free, Equilibrium Dialysis