T4 (Thyroxine), Total with Reflex to TSH | Test Detail

T₄ (Thyroxine), Total with Reflex to TSH

Test Code

37675

CPT Code(s)

84436

CPT Code is subject to a Medicare Limited Coverage Policy and may require a signed ABN when ordering.

Test Code

37675

CPT Code(s)

84436

CPT Code is subject to a Medicare Limited Coverage Policy and may require a signed ABN when ordering.

This test is not available in all locations. Please provide SERVICE AREA INFORMATION to confirm Test Code for the lab that services your account or to find available tests you can order.

In-home collection is not available in your area through Quest Mobile.

Clinical Significance

T₄ (Thyroxine), Total with Reflex to TSH - For diagnosis of hypothyroidism and hyperthyroidism.

Test Resources

None found for this test
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Test Details

Includes

If T4 (Thyroxine), Total is <4.5 mcg/dL or >12.0 mcg/dL, then TSH will be performed at an additional charge (CPT Code(s): 84443).

Methodology

Immunoassay (IA)

Reference Range(s)

T4 (Thyroxine), Total

	Male (mcg/dL)	Female (mcg/dL)
<1 Month	4.5-17.2	4.5-17.2
1-23 Months	5.9-13.9	5.9-13.9
2-12 Years	5.7-11.6	5.7-11.6
13-20 Years	5.1-10.3	5.3-11.7
>20 Years	4.9-10.5	5.1-11.9

Free T4 Index (T7)

1.4-3.8

LOINC® Codes, Performing Laboratory

Service Area must be determined

Includes

If T4 (Thyroxine), Total is <4.5 mcg/dL or >12.0 mcg/dL, then TSH will be performed at an additional charge (CPT Code(s): 84443).

Methodology

Immunoassay (IA)

Reference Range(s)

T4 (Thyroxine), Total

	Male (mcg/dL)	Female (mcg/dL)
<1 Month	4.5-17.2	4.5-17.2
1-23 Months	5.9-13.9	5.9-13.9
2-12 Years	5.7-11.6	5.7-11.6
13-20 Years	5.1-10.3	5.3-11.7
>20 Years	4.9-10.5	5.1-11.9

Free T4 Index (T7)

1.4-3.8

LOINC® Codes, Performing Laboratory

Service Area must be determined

Preferred Specimen(s)

1 mL serum

Alternative Specimen(s)

Sodium heparin (green-top) tube

Minimum Volume

0.5 mL

Transport Container

Serum separator tube (SST)

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Setup Schedule

Service Area must be determined

Preferred Specimen(s)

1 mL serum

Alternative Specimen(s)

Sodium heparin (green-top) tube

Minimum Volume

0.5 mL

Transport Container

Serum separator tube (SST)

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 7 days
Frozen: 28 days

Setup Schedule

Service Area must be determined

This test is not available in all locations. Please provide ACCOUNT INFORMATION NEEDED to confirm Test Code for the lab that services your account or to find available tests you can order.

In-home collection is not available in your area through Quest Mobile.

Test Details

Clinical Significance

Test Resources

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 guidance 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.

This material contains content from LOINC® (http://loinc.org). The LOINC Table, LOINC Table Core are copyright © 1995-2019, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license.

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