Quantitative Thyroglobulin without Thyroglobulin Antibodies

Test Code

15561

CPT Codes
84432

Preferred Specimen

2 mL serum collected in a serum separator tube (SST)

Patient Preparation
Dietary supplements containing biotin may interfere in assays and may skew results to be either falsely high or falsely low. For patients receiving the recommended daily doses of biotin, draw samples at least 8 hours following the last biotin supplementation. For patients on mega-doses of biotin supplements, draw samples at least 72 hours following the last biotin supplementation.

Minimum Volume

1 mL

Instructions

Administration of STRENSIQ may interfere in certain assays and may falsely elevate values. For patients receiving STRENSIQ, consideration should be given to using alternate methods.

Transport Temperature

Room temperature

Specimen Stability

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

Methodology
Immunoassay (IA)

Setup Schedule

Set up: Tues-Sat; Report available: 1-2 days

Reference Range

Intact Thyroid	2.8-40.9 ng/mL
Athyrotic	<0.1 ng/mL

Note: Abnormal flagging is based on the reference interval for patients with intact thyroid.

Clinical Significance

Thyroglobulin (TG) is a secretory product only of the thyroid gland. The major clinical use of serum TG measurement is to monitor, but not to diagnose, patients with well-differentiated thyroid cancers. The measurement of thyroglobulin, after thyroidectomy and ablation of the thyroid gland, is useful to determine metastasis. Deficient TG synthesis is observed in infants with goitrous hypothyroidism. With immunometric assays (sandwich assays), TGAB interference typically produces inappropriately low TG results, most likely caused by endogenous TG immune complexes that block one or more of the reagent Ab from binding endogenous TG.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.