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Test Name

T4 Free, Direct Dialysis

To view specimen requirements and codes please Select a regional laboratory.

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CPT Code(s)**

84439
**IMPORTANT: CPT Code is informational only; obtain the Test Code for ordering.

Methodology

Equilibrium Dialysis • Chromatography/Mass Spectrometry

Reference Range(s)

Adult 0.9-2.2 ng/dL
Prematures, 25-30 Weeks  
  Birth-7 Days 0.5-3.3 ng/dL
Prematures, 31-36 Weeks
  Birth-7 Days 1.3-4.7 ng/dL
Cord Blood, >37 Weeks 1.2-2.2 ng/dL
Birth-4 Days 2.2-5.3 ng/dL
2 Months-2 Years 1.2-2.5 ng/dL
3 Years-17 Years 1.0-2.4 ng/dL
Pregnancy  
  First Trimester 0.9-2.0 ng/dL
  Second Trimester 0.8-1.5 ng/dL
  Third Trimester 0.8-1.7 ng/dL

Clinical Significance

For the differential diagnosis of euthyroid hyperthyroxinemia from hyperthyroidism or for the differential diagnosis of euthyroid hypothyroxinemia from hypothyroidism.

Test FAQ

T4, Free

Alternative Name(s)

Free T4 By Equilibrium Dialysis,Thyroxine, Free By Direct Dialysis,Direct Free T4,Free T4 Direct Dialysis,FT4 Direct Dialysis,Free Thyroxine

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.

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T4 Free, Direct Dialysis
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