A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

T4 Free, Direct Dialysis and T4 Total

Test Code
36725


CPT Codes
84436, 84439

Preferred Specimen
2 mL serum


Patient Preparation
Fasting preferred

Minimum Volume
1 mL


Instructions
Please specify on the request form the patients age.


Transport Temperature
Refrigerated (cold packs)


Specimen Stability
Room temperature: 4 days
Refrigerated: 7 days
Frozen: 28 days


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Lipemia • Heparin plasma • EDTA plasma


Methodology
Equilibrium Dialysis • Chromatography/Mass Spectrometry • Chemiluminescence (CL)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule
Set up: Mon-Sat a.m.; Report available: 4-5 days


Reference Range
T4, Free Direct Dialysis
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

T4, Total
<1 Month Not established
1-23 Months 6.0-13.2 mcg/dL
2-12 Years 5.5-12.1 mcg/dL
13-20 Years 5.5-11.1 mcg/dL
>20 Years 4.8-10.4 mcg/dL
Pregnancy  
  First Trimester 6.4-15.2 mcg/dL
  Second Trimester 7.4-15.2 mcg/dL
  Third Trimester 7.7-13.8 mcg/dL
  All TrimestersTogether 7.0-14.7 mcg/dL


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


Performing Laboratory
Quest Diagnostics Nichols Institute-San Juan Capistrano, CA
33608 Ortega Highway
San Juan Capistrano, CA 92675-2042




The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.