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Test Code LAB126 T4, TOTAL

Important Note

Important Note

Important Note  

The Thyroid cascade is a reflex test where the reflex is part of the order and there is no option to decline the testing. TSH is done first. If the TSH is outside normal range a Free-T4 is ordered automatically (CPT: 84439). If the TSH is low and the Free-T4 is normal based on the appropriate reference range for the age/sex of the patient a Total -T3 is ordered (CPT: 84480).

Test subject to Medicare National Coverage Determination (NCD) 190.22 THYROID TESTING

See Sidebar Medical Necessity

Specimen Information

Container Specimen Temperature Collect Vol Submit Vol Min Vol Stability
SST  Serum Refrigerate 4 mL 0.5 mL 0.2 mL 5 days
Lithium Heparin (Green Top) Plasma Refrigerate 4 mL 0.5 mL 0.2 mL 5 days

*While a green microtainer is an optional tube type in rare circumstances, it is not recommended.

Test Schedule / Analytical Time / Test Priority

Daily / Same day / Available STAT

Reference Range

Age Sex Low High Units
0 - 14 days All 3.2 24.7 ug/dL
14 days - 4 years All 6.9 18.7 ug/dL
4 years - 15 years All 6.2 10.8 ug/dL
15 years - 18 years Male 5.7 9.3 ug/dL
15 years - 18 years Female 6.0 15.5 ug/dL
≥18 years All 5.5 11.0 ug/dL

 

CPT(s)

Description CPT Code
T4 84436

 

Method

Chemiluminescence Immunoassay

Instrumentation

Ortho Vitros 5600

Performing Location

University of Vermont Medical Center

Section

Chemistry-1

Is the UVMMC lab NY State Certified to perform this testing?  Yes/No

Yes