T4 Free, Direct Dialysis : 35167

Test Code

T4DIRQ or 35167

Alias/See Also

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

CPT Codes
84439

Instructions

Fasting preferred

Please specify the patient's age on the request form

Transport Container

Preferred Specimen
1 mL serum

Minimum Volume
0.5 mL

Transport Temperature

Refrigerated.

Specimen Stability

Room temperature: 4 days; Refrigerated: 14 days; Frozen: 35 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Lipemia, Heparin plasma, EDTA plasma

Methodology
Equilibrium Dialysis, Chromatography/Mass Spectrometry

Setup Schedule

Monday - Saturday

Report Available

3-4 days (From receipt at performing Laboratory)

Reference Range

Reference Ranges

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

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

Performing Laboratory
Quest Diagnostics

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.