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Test Code T4T Total T4 Level

Important Note

Medicare frequency limitations exist for this test in addition to diagnosis requirements. Click on link for list of medically necessary diagnoses: http://www.munsonhealthcare.org/medical-necessity. Click on link for Advance Beneficiary Notice of Noncoverage form: Advance Beneficiary Notice of Noncoverage

EHR Test Codes

  Test Code Test Name
Atlas T4T T4 Total
Cerner   Total T4 Level

Specimen Requirements

Preparation of Patient: 

None

 

Container Type: 

Gold Top 6mL SST Gel & Clot Activator Tube

Specimen Type:

Serum

 

Specimen Volume: 

2.5 mL Serum minimum .5 mL

 

Specimen Handling/Transport:

Separate serum from cells within 2 hours of collection.

Transport ambient room temperature, refrigerated and/or frozen.

 

Specimen Stability/Storage:

8 hours ambient room temperature

1 day refrigerated 2-8°C

>1 day frozen -20°C

Performing Laboratory

Munson Medical Center Laboratories

Chemistry Department

Priority, Frequency, & Turnaround

Priority:

Non-Emergent

 

Frequency:

24 hours 7 days a week

 

Turnaround:

0 - 1 days

Methodology

Chemiluminescence Immunoassay

Reporting

Reference Range:

 0 years - 19 years none

> 19 years 6.1 - 12.2 ug/dL

 

 

Critical Decision:

None

Clinical Significance

T4 and T3 regulate normal growth and development. They maintain body temperature, stimulate calorigenesis and affect all aspects of carbohydrate metabolism as well as certain areas of lipid and vitamin metabolism. Fetal and neonatal development also require thyroid hormones.

 

Thyroxine is commonly measured in human serum as total T4, measuring both bound and free T4. It is used as a thyroid screening test alone or in conjunction with other thyroid tests. Measurement of total T4 gives a reliable reflection of clinical thyroid status in the absence of binding abnormalities. However, changes in binding proteins can occur which affect the level of total T4 but leave the level of unbound hormone unchanged.

CPT Code(s)

84436