THYROID ANTIBODIES
meduploader - 06-29-09 15:31

Thyroglobulin (Tg) antibodies: Found in 50–60% of patients with Graves’ disease and in 90% of those with early Hashimoto’s thyroiditis. If present, thyroglobulin assay is not reliable.
Thyroid peroxidase (TPO) antibodies: Antibodies to a thyroid-specific enzyme (TPO); present in 50–80% of Graves’ disease patients and in > 90% of those with Hashimoto’s thyroiditis.
Thyroid-stimulating immunoglobulin (TSI): Stimulates the receptor to produce more thyroid hormone; present in 80–95% of Graves’ patients.
RADIONUCLIDE UPTAKE AND SCAN OF THE THYROID GLAND
The test is performed as follows:
123I is administered orally, and the percent of radioiodine uptake is obtained at 4–6 and 24 hours
The test is usually accompanied by a scan to determine the geographic distribution of its functional activity (i.e., to determine if hot or cold nodules are present).
A hot nodule implies overactivity of the nodule.
A cold nodule implies no activity of the nodule. Most malignant nodules are cold.
Most often used to determine the etiology of hyperthyroidism; not useful in the evaluation of hypothyroidism.
Also used to follow patients with thyroid cancer after thyroidectomy. Can be used to determine the dose for 131I radioiodine thyroid ablation.