Thyroxine, Free (Free T4)

0070138
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Example Reports
Abnormal
Normal

Ordering Recommendation

Not the preferred initial thyroid disorder screening test. Order following an abnormal thyroid stimulating hormone (TSH) result to diagnose thyroid disease. Order in conjunction with Thyroid Stimulating Hormone (0070145) in cases of suspected secondary hypothyroidism.

Mnemonic

FT4

Methodology

Quantitative Electrochemiluminescent Immunoassay

Performed

Sun-Sat

Reported

Within 24 hours

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Serum separator tube or plasma separator tube. Also acceptable: Green (lithium heparin), lavender (K3EDTA or K2EDTA ) or pink (K2EDTA).

Specimen Preparation

Allow specimen to clot completely at room temperature. Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Grossly hemolyzed specimens.

Remarks
Stability

After separation of cells: Ambient: 5 days; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

Effective February 22, 2022

Free Thyroxine, ng/dL
0-3 days 0.7-2.7 ng/dL
4-30 days 0.8-3.1 ng/dL
1-23 months 0.5-2.3 ng/dL
2-6 years 0.9-1.8 ng/dL
7-11 years 0.9-1.7 ng/dL
12-19 years 0.9-1.6 ng/dL
20 years and older 0.9-1.7 ng/dL
Pregnancy, 1st Trimester 0.9-1.4 ng/dL
Pregnancy, 2nd Trimester 0.7-1.3 ng/dL

Interpretive Data



Compliance Category

FDA

Note

Hotline History

View Hotline History

 

Hotline History

Date of Change
Test Name Change
Methodology
Performance/Reported Schedule
Specimen Requirements
Reference Interval
Interpretive Data
Note
CPT Code
Component Change
Other Interface Change
New Test
Inactive
02/22/2022
X
X
N/A

CPT Codes

84439

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Components

Component Test Code* Component Chart Name LOINC
0070138 Thyroxine Free 3024-7
* 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

  • Free Thyroxine
  • FT4, Serum
  • Non-Protein Bound Tetraiodothyronine
  • T4 Free, Serum
  • T4, Free
  • Thyroid Function Cascade
Thyroxine, Free (Free T4)