TSH with Reflex to Free T4 | Test Detail

TSH with Reflex to Free T₄

Test Code

36127

CPT Code(s)

84443

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

Test Code

36127

CPT Code(s)

84443

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

Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano. Please provide SERVICE AREA INFORMATION to find available tests you can order.

In-home collection may be available in your area for purchase through Quest Mobile.

Clinical Significance

TSH with Reflex to Free T₄ - This test may be useful in assessing thyroid dysfunction when pituitary disease is not suspected. In patients with clinical suspicion of hyperthyroidism or hypothyroidism, testing thyroid stimulating hormone (TSH) is the initial step [1]. An abnormal TSH result will reflex to a free thyroxine (T4) test to aid in diagnosis and guide further testing if needed.

TSH stimulates the thyroid gland to synthesize and secrete triiodothyronine (T3) and T4. TSH production is reduced in response to high T3/T4 levels and increased in response to low T3/T4 levels. When pituitary disease is not suspected, ...

Test Resources

Algorithm

Testing Algorithm for Thyroid Dysfunction in Nonpregnant Adults

Clinical Focus

Thyroid Dysfunction in Nonpregnant Adults

Test Details

Includes

For patients 1 year of age or older, TSH will be performed first.
If TSH is abnormal (elevated or decreased) based on age/gender specific reference range, then a Free T4 will be performed at an additional charge (CPT code(s): 84439).

Patient Preparation

Specimen collection after fluorescein dye angiography should be delayed for at least 3 days. For patients on hemodialysis, specimen collection should be delayed for 2 weeks after angiography.
According to the assay manufacturer Siemens: samples containing fluorescein can produce falsely depressed values.

Methodology

Immunoassay (IA)

Reference Range(s)

Premature Infants (28-36 Weeks)
1st Week of Life	0.20-27.90 mIU/L
Term Infants (>37 Weeks)
Serum or Cord Blood	1.00-39.00 mIU/L
1-2 Days	3.20-34.60 mIU/L
3-4 Days	0.70-15.40 mIU/L
5 Days-4 Weeks	1.70-9.10 mIU/L
1-11 Months	0.80-8.20 mIU/L
1-19 Years	0.50-4.30 mIU/L
≥20 Years	0.40-4.50 mIU/L
Pregnancy
First Trimester	0.26-2.66 mIU/L
Second Trimester	0.55-2.73 mIU/L
Third Trimester	0.43-2.91 mIU/L

TSH levels decline rapidly during the first week of life in most children, but may remain transiently elevated in a few individuals despite normal free T4 levels. For proper interpretation of an abnormal TSH from a newborn thyroid screen, a Free T4 by Dialysis (test code 35167) or Total T4 (test code 867) should be considered.

Alternative Name(s)

Thyroid Stimulating Hormone with Reflex

LOINC® Codes, Performing Laboratory

Service Area must be determined

Includes

For patients 1 year of age or older, TSH will be performed first.
If TSH is abnormal (elevated or decreased) based on age/gender specific reference range, then a Free T4 will be performed at an additional charge (CPT code(s): 84439).

Patient Preparation

Methodology

Immunoassay (IA)

Reference Range(s)

Premature Infants (28-36 Weeks)
1st Week of Life	0.20-27.90 mIU/L
Term Infants (>37 Weeks)
Serum or Cord Blood	1.00-39.00 mIU/L
1-2 Days	3.20-34.60 mIU/L
3-4 Days	0.70-15.40 mIU/L
5 Days-4 Weeks	1.70-9.10 mIU/L
1-11 Months	0.80-8.20 mIU/L
1-19 Years	0.50-4.30 mIU/L
≥20 Years	0.40-4.50 mIU/L
Pregnancy
First Trimester	0.26-2.66 mIU/L
Second Trimester	0.55-2.73 mIU/L
Third Trimester	0.43-2.91 mIU/L

Alternative Name(s)

Thyroid Stimulating Hormone with Reflex

LOINC® Codes, Performing Laboratory

Service Area must be determined

Preferred Specimen(s)

1 mL serum

Minimum Volume

0.7 mL

Collection Instructions

This assay should only be ordered on patients 1 year of age or older. Orders on patients younger than 1 year will have a TSH only performed.

Transport Container

Serum separator tube (SST)

Transport Temperature

Room temperature

Specimen Stability

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

Reject Criteria

Plasma

Setup Schedule

Service Area must be determined

Preferred Specimen(s)

1 mL serum

Minimum Volume

0.7 mL

Collection Instructions

This assay should only be ordered on patients 1 year of age or older. Orders on patients younger than 1 year will have a TSH only performed.

Transport Container

Serum separator tube (SST)

Transport Temperature

Room temperature

Specimen Stability

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

Reject Criteria

Plasma

Setup Schedule

Service Area must be determined

Not offered in Quest Diagnostics Nichols Institute (IFD) – San Juan Capistrano. Please provide SERVICE AREA INFORMATION to find available tests you can order.

In-home collection may be available in your area for purchase 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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