Thyroglobulin
(Tg)

Sample type :

serum

Uses

1. measure the amount of Tg in the blood and to evaluate the effectiveness of thyroid cancer treatment or to monitor for a recurrence of thyroid cancer after treatment is completed.

2. To diagnose factitious hyperthyroidism: Tg is very low or not detectable in factitious hyperthyroidism and is high in all other types of hyperthyroidism (e.g., thyroiditis, Graves disease).

3. To predict outcome of therapy for hyperthyroidism; higher remission rates in patients with lower Tg values. Failure to become normal after drug-induced remission suggests relapse after drugs as discontinued.

4. To diagnose thyroid agenesis in newborn.

Precacutions

No special precautions is needed before a Tg test , but your health care provider may ask you to avoid taking multivitamins or dietary supplements at least 12 hours before sample collection.

Measure Tg levels is usually ordered every three to six months during the first year following treatment.

Interfering factors

• This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 12 hours prior to the collection of a sample.

• A Tg test is not recommended for initial diagnosis of thyroid carcinomas. The presence of Tg in pleural effusions indicates metastatic differentiated thyroid cancer.

• A Tg test should not be used in patients with pre existing thyroid disorders.

• Because Tg autoantibodies can interfere with both competitive immunoassays and immunometric assays for Tg, all patients should be screened for Tg autoantibodies by a sensitive immunoassay; recovery studies are not adequate for ruling out interference by these autoantibodies.

Pre-analytical errors

1. If the sample was unlabeled .

The corrective action

• Reject the sample and require another one and make sure that all data of the patient is correct.

2.if the patient taken vitamins or dietary supplements before coming to the laboratory.

The corrective action

• You should tell the patient that he should refrain from taking vitamins at least 12hr before sample collection.

Post-analytical errors

1. write wrong name on the report or wrong results and send the report to the patient.

The Corrective action

• If the report is delivered to the patient, you must communicate with the patient and apologize for this mistake and sent the right report.

Reference range

Male: 1,40 -29,2 ng/ml

Female: 1,50 – 38,5 ng/ml