Thyroxine, Free by Equilibrium Dialysis/HPLC-Tandem Mass Spectrometry
Ordering Recommendation
Not recommended for routine evaluation of thyroid disorders. Order Thyroxine, Free (Free FT4) (0070138), instead.
Quantitative Equilibrium Dialysis/High Performance Liquid Chromatography-Tandem Mass Spectrometry
Sun, Tue, Thu
2-5 days  
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
Specimen Required
Patient Preparation
Plain red.  
Specimen Preparation
Transfer 2 mL serum to an ARUP Standard Transport Tube. (Min: 0.3 mL)  
Storage/Transport Temperature
Unacceptable Conditions
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:
Statement B: 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.
CPT Code(s)
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.
  • Direct Dialysis
  • FT4
  • T4, Free, Equilibrium Dialysis