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Thyroxine (T4)
| Test Code | B0004 |
|---|---|
| Test Summary |
This biochemical test analyzes the level of thyroxine (T4) |
| Turn Around Time | 3 days |
| Acceptable Sample Types | Dried Blood Spots |
| Acceptable Billing Types | Institutional Billing , Self (patient) Payment |
| NY Approved | Yes |
| Self (patient) Price | $108.90 |
| Institutional Price | $108.90 |
**The CPT codes listed are in accordance with Current Procedural Terminology, a publication of the American Medical Association, and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party.
This testing service has not been cleared or approved by the U.S. Food and Drug Administration. Testing services may not be licensed in accordance with the laws in all countries. The availability of specific test offerings is dependent upon laboratory location.
Test Description
Low levels of thyroxine are associated with congenital hypothyroidism.
Indications for Testing
- Infants with symptoms of hypothyroidism, sleepiness, decreased activity, difficulty feeding, constipation, intellectual disability, and growth retardation.
- Individuals with a family history of congenital hypothyroidism.
Condition Description
Congenital hypothyroidism is a disease associated with loss of function of the thyroid gland. Onset is in infancy, and symptoms can include sleepiness, decreased activity, difficulty feeding, constipation, intellectual disability, and growth retardation. The incidence of congenital hypothyroidism is estimated to be ~ 1 in 2,000.
Test Methods and Limitations
Fluoroimmunometric assay is based on the direct sandwich technique in which two antibodies are directed against a given analyte. Calibrators and serum samples containing the analyte are reacted with immobilized monoclonal antibodies directed against the analyte. Europium-labeled monoclonal antibodies directed against an antigenic site on the analyte are reacted with the analyte bound to the solid-phase antibody. The Inducer dissociates europium ions from the labeled antibodies into the solution, where they form highly fluorescent chelates with components of the Inducer. The fluorescence in each cup is then measured. The europium fluorescence from each sample is proportional to the analyte concentration in the sample.
Detailed Sample Requirements
Dried Blood Spots
| Collection Container(s) | Dried blood spot card |
|---|---|
| Collection | Follow kit instructions. Briefly, allow blood to saturate the card until indicated areas are filled and blood has soaked through the card. Air dry the card at ambient temperature for at least 3 hours.
|
| Sample Condition | Follow the instructions provided with the collection set. Store the dried blood at ambient temperature for up to two days. If the specimen cannot be sent as soon as it is dry, the filter paper should be placed in a sealable plastic bag and stored in a refrigerator (≤ 8°C) or preferably in a freezer. |
| Shipping | Follow kit instructions. Double bag and ship overnight at ambient temperature. |