Assay

Anti-Tg Antibody

Thyroglobulin (Tg) is a glycoprotein found in thyroid follicular cells that plays a critical role in the biosynthesis of key thyroid hormones. The measurement of anti-Tg antibody has been shown to be an aid in the diagnosis of Hashimoto’s thyroiditis and Graves’ disease. The Siemens anti-Tg antibody assay provides a precise, quantitative determination of anti-Tg antibody in serum or plasma.

Anti-TPO Antibody

Anti-thyroid peroxidase antibody (anti-TPO antibody), a protein found in thyroid follicular cells, is a catalyst in the synthesis of key thyroid hormones. Autoimmune thyroid diseases are characterized by the presence of anti-TPO antibody.

Elevated levels of anti-TPO antibody are a risk factor for:

• Autoimmune thyroid disease, including Hashimoto’s thyroiditis, Graves' disease, atrophic thyroiditis and primary myxedema
• Postpartum thyroiditis in women

The Siemens anti-TPO antibody assay is a competitive immunoassay that uses chemiluminescent technology. It is a highly sensitive test for the detection of anti-TPO Ab2, giving laboratorians an accurate, quantitative determination of anti-TPO antibody in serum or plasma.

Free T3

Triiodothyronine (T3) is a hormone synthesized and secreted from the thyroid gland, and formed by peripheral deiodination of T4. T3 plays an important role in regulating metabolism. In the circulation, 99.7% of T3 is reversibly bound to transport proteins. Unbound T3 (Free T3) is metabolically active. The Free T3 test helps determine whether the thyroid is functioning properly. It is ordered primarly to help diagnose hyperthyroidism and may be ordered to help monitor the progress of a patient with a known thyroid disorder. Free T3 test is usually ordered following an abnormal TSH and T4 test. Free T3 testing may be ordered along with thyroid antibodies to help diagnose Graves’ disease, an autoimmune disorder that is the most common cause of hyperthyroidism.

Free T4

Thyroxine (T4) is a hormone synthesized and secreted by the thyroid gland and plays an important role in regulating metabolism. In the circulation, 99.95% of T4 is reversibly bound to transport proteins. The remaining T4 is not bound to transport proteins, but is free in the circulation. This unbound fraction, free T4, is metabolically active. An appropriate FT4 assay used in combination with TSH is considered by the American Thyroid Association to be “…the best and most efficient combination of blood tests for the diagnosis and follow-up of most patients with thyroid disorders.” (http://jama.ama-assn.org)

Intact PTH

Intact PTH is intended as an aid in the differential diagnosis of hyperparathyroidism, hypoparathyroidism, or hypercalcemia of malignancy. Siemens' Intact PTH assay provides the quality and specificity necessary in the management of patients with diseases of the parathyroid gland.

T Uptake

Also known as T3 Resin Uptake (T3RU) or Thyroid Uptake, this test estimates how much thyroid hormone-binding proteins are available in the blood through a calculation based on levels of T3 or T4 added to a patient’s blood sample.

TBG

Thyroxine-binding globulin (TBG) binds thyroid hormones in circulation. It is one of three proteins responsible for carrying T3 and T4 into the bloodstream. TBG tests are sometimes used in finding the reason for elevated or diminished levels of thyroid hormone.

Thyroglobulin

The most important characteristic of a Thyroglobulin assay is how reliably the assay discriminates between the assay’s functional sensitivity and the lower limit of the normal reference range – signaling residual thyroid tissue after thyroid ablation.

Thyroglobulin aids in monitoring patients who have undergone thyroidectomy. Siemens offers an automated and reliable Thyroglobulin test that exceeds the high-performance characteristics necessary for identifying the presence or absence of functioning thyroid tissue.

Total T3

For quantitative measurement of total triiodothyronine (T3) hormone in human serum and plasma. Measurements of T3 are used in the diagnosis and treatment of thyroid diseases such as hyperthyroidism and T3-thyrotoxicosis.

Total T4

Total T4 is a hormone used to help diagnose hyper- and hypothyroidism. The Total T4 test is usually ordered with a TSH test to help determine whether the thyroid hormone feedback system is functioning properly, and the results help to distinguish between causes of hyper- and hypothyroidism.

TSH

Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to synthesize and secrete thyroid hormone. TSH serum measurements are used to detect primary hypo- and hyperthyroidism. The capability of a TSH assay to distinguish between normal and subnormal concentrations is essential for thyroid testing strategy. Quantification of TSH at a lower value of 0.01 mlU/L yields information that is useful to clinicians referring patients with subnormal TSH concentrations. Siemens’ TSH assays consistently deliver sensitive, highly specific results, across multiple platforms.
 

TSI
TSI measurements are also used to monitor the response to GD therapy and prediction of remission or relapse, confirming Graves' ophthalmopathy, and for predicting neonatal thyroid hyperthyroidism.^1,2 Incorporating the TSI assay into existing diagnostic algorithms has been shown to reduce overall direct costs of GD diagnosis by up to 43%, with the net cost of avoiding misdiagnosis reduced by up to 85%.³

The IMMULITE^® 2000/2000 XPi TSI assay is the first automated and quantitative TSI assay available today. TSH receptor antibody (TRAb) assays detect both thyroid blocking and stimulating antibodies. However, blocking antibodies inhibit TSH stimulation of thyroid cells and lead to hypothyroidism. The IMMULITE 2000/2000 XPi TSI assay detects only thyroid stimulating antibodies, the specific cause of GD pathology. With a 65-minute total assay time and ready-to-use, stable reagents, the use of this assay can make the differential diagnosis of GD faster and easier, allowing patients to be diagnosed and treated sooner.

3rd Generation TSH

Improvements in the sensitivity of TSH assays allow it to be used for detecting both hyper- and hypothyroidism. Assays with a functional sensitivity of <0.02 mIU/L are classified as “third generation” assays. The 3rd Generation TSH assay from Siemens is sensitive and precise, with imprecision performance that exceeds the criteria recommended by the NACB for TSH methods.