Davis's Lab & Diagnostic Tests

Thyroid-Binding Inhibitory Immunoglobulin

General

Synonym/Acronym:
Thyrotropin receptor antibodies, thyrotropin-binding inhibitory immunoglobulin, TBII.

Common Use:
To assist in diagnosing Graves’ disease related to thyroid function.

Specimen:
Serum (1 mL) collected in a red-top tube.

Normal Findings:
(Method: Electrochemiluminescence) 0.0–1.75 units/L.

Description

There are two functional types of thyroid receptor immunoglobulins: thyroid-stimulating immunoglobulin (TSI) and thyroid-binding inhibitory immunoglobulin (TBII). TSI reacts with the receptors, activates intracellular enzymes, and promotes epithelial cell activity that operates outside the feedback regulation for thyroid-stimulating hormone (TSH) (see monograph titled “Thyroid-Stimulating Immunoglobulin”); TBII blocks the action of TSH and is believed to cause certain types of hyperthyroidism. These antibodies were formerly known as long-acting thyroid stimulators. High levels in pregnancy may have some predictive value for neonatal thyrotoxicosis: A positive result indicates that the antibodies are stimulating (TSI); a negative result indicates that the antibodies are blocking (TBII). TBII testing measures thyroid receptor immunoglobulin levels in the evaluation of thyroid disease.

Indications

  • Evaluate suspected acute toxic goiter
  • Investigate suspected neonatal thyroid disease secondary to maternal thyroid disease
  • Monitor hyperthyroid patients at risk for relapse or remission

Potential Diagnosis

Increased In:

Evidenced by antibodies that block the action of TSH and result in hyperthyroid conditions.

  • Graves’ disease
  • Hyperthyroidism (various forms)
  • Maternal thyroid disease
  • Neonatal thyroid disease
  • Toxic goiter

Decreased In:
N/A

Critical Findings

N/A

Interfering Factors

  • Lithium may cause false-positive results.

Nursing Implications Procedure

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in evaluating thyroid function.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s endocrine system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • There are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • If the patient has a history of allergic reaction to latex, avoid the use of equipment containing latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post Test

  • A report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

Thyroid-Binding Inhibitory Immunoglobulin is a sample topic found in
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