Thyroxine, Free by Equilibrium Dialysis/HPLC-Tandem Mass Spectrometry
0093244
Ordering Recommendation
Not recommended for routine evaluation of thyroid disorders. Order Thyroxine, Free (Free FT4) (0070138), instead.
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
Specimen Required
Patient Preparation
  
Collect
Plain red.  
Specimen Preparation
Transfer 2 mL serum to an ARUP Standard Transport Tube. (Min: 0.3 mL)  
Storage/Transport Temperature
Refrigerated.  
Unacceptable Conditions
  
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
Age Female Male
25-​30 weeks gestation 0.5-​3.3 ng/dL 0.5-​3.3 ng/dL
31-​36 weeks gestation 1.3-​4.7 ng/dL 1.3-​4.7 ng/dL
Birth to 1 week 2.2-​5.3 ng/dL 2.2-​5.3 ng/dL
2-​3 weeks 0.9-​4.0 ng/dL 0.9-​4.0 ng/dL
1-​5 months 1.1-​2.2 ng/dL 1.1-​2.2 ng/dL
6 months-​6 years 1.4-​2.7 ng/dL 1.4-​2.7 ng/dL
7 years-​17 years 1.1-​2.0 ng/dL 1.1-​2.0 ng/dL
18 years and older 1.1-​2.4 ng/dL 1.1-​2.4 ng/dL
Pregnancy, 1st Trimester 0.7-​2.0 ng/dL  
Pregnancy, 2nd Trimester 0.7-​2.1 ng/dL  
Pregnancy, 3rd Trimester 0.5-​1.6 ng/dL  
Interpretive Data


See Compliance Statement B: www.aruplab.com/CS  
Note
 
CPT Code(s)
84439
Components
Component Test Code*Component Chart Name
0093244Free T4 by Equil Dialysis-TMS
* 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