ARUP's Laboratory Test Directory

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

Test Mnemonic: FT4 ED-TMS
Methodology: Equilibrium Dialysis/High Performance Liquid Chromatography-Tandem Mass Spectrometry

Performed: Mon-Fri

Reported: 2-5 days

Specimen Required:  
Collect: One 5 mL plain red.

Transport: 2 mL serum at 2-8°C. (Min: 1 mL) Submit specimen in an ARUP Standard Transport Tube.

Pediatric Collection/Transport: 0.5 mL serum at 2-8°C.

Remarks: Avoid use of serum separator tubes and gels.

Stability: After separation from cells: Ambient: 4 days; Refrigerated: 2 weeks; Frozen: 1 month

Reference Interval:
 
Age Thyroxine ng/dL
25-30 weeks gestation:
31-36 weeks gestation:
Birth to 1 week:
2-3 weeks:
1-11 months:
12 months - 18 years:
3-18 years:
19 years and older: 		0.5-3.3 ng/dL
1.3-4.7 ng/dL
2.2-5.3 ng/dL
0.9-4.0 ng/dL
1.1-2.2 ng/dL
1.0-2.0 ng/dL
1.0-2.0 ng/dL
1.1-2.4 ng/dL
Pregnancy:
1st Trimester:
2nd Trimester:
3rd Trimester: 		Pregnancy:
0.7-2.0 ng/dL
0.7-2.1 ng/dL
0.5-1.6 ng/dL

CPT Code(s):
84439