Health Lab

Test Name:

TSH/REFLEX FREE T4/REFLEX FREE T3

Test Code:

2120256

CPT Code(s):

84443

Test Includes:

For TSH reflex FT4/ reflex FT3, see parameters listed below:

Free T4: Will reflex if the TSH is < 0.30 µIU/mL or > 5.33 µIU/mL

Free T3: Will reflex if the TSH is < 0.30 µIU/mL or > 5.33 µIU/mL and the Free T4 is < 0.8 ng/dL

Additional charges/CPT codes will apply.

Preferred Specimen:

2.0 mL serum

Container:

SST (gold)

Alternate Container:

Lithium Heparin

Minimum Volume:

0.5 mL serum or plasma
This volume does not allow for repeat testing.

Collection Instructions:

Allow specimen to completely clot (this can take up to 60 minutes). Centrifuge for 15 minutes. If the specimen is collected in a tube without a gel barrier, centrifuge and transfer the plasma into a properly labeled transfer tube within 2 hours of collection.

Transport Temperature:

Refrigerated

Stability:

Room temperature: 72 hours

Refrigerated: 7 days
Frozen: 1 month

Rejection Criteria:

Hemolysis

Schedule:

Set up Daily; Results in 24-48 hours

Method:

Paramagnetic-particle, chemiluminescent immunoassay

Clinical Significance:

The principal clinical use for hTSH measurement is for the assessment of thyroid status. hTSH is measured to: 1) Exclude hypothyroidism (elevated levels of hTSH) or hyperthyroidism (depressed or nondetectable levels of hTSH). 2) Monitor T4 replacement treatment in primary hypothyroidism or antithyroid treatment in hyperthyroidism. 3) Follow T4 suppression of the trophic influence of hTSH is “cold nodules” and non-toxic goiter. 4) Assess the response to TRH stimulating testing. As more sensitive and precise methods become available, hTSH measurements are also increasingly used to identify subclinical or latent hypothyroidism or hyperthyroidism.

Use:

Updated 02/17/22

Reference Range Table

Result	Units	Gender	Age	Range
TSH	µIU/mL	Both	0 Year - 999 Year	0.3 - 5.0

The CPT codes included in this publication are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are provided here for the convenience of our clients; however, correct coding often varies from one carrier to another, and HealthLab may bill specific carriers using codes other than those shown. Clients who bill for services should verify the code(s) with the applicable payor to confirm that their use is appropriate in each case.