Biomarkers · Chemical
A plain-language description with its source has not been added for this biomarker yet. What the laboratories say about the tests that measure it is below.
What the laboratory says this test is for
T3 measurements are used to diagnose hyperthyroidism. This test can also be used to clarify thyroid status in the presence of possible protein-binding abnormalities.
Quest Diagnostics test directory, test code 36598
What the laboratory says this test is for
This panel provides an assessment of thyroid function and includes tests for thyroid stimulating hormone (TSH), total thyroxine (T4), triiodothyronine (T3) uptake (T3 resin uptake), and free T4 index. This panel may be useful for evaluating thyroid function when pituitary disease is not suspected. The results of the panel may help in the diagnosis of hyperthyroidism and hypothyroidism [1].T3 and T4 are hormones derived from the thyroid and released into the blood to regulate metabolism. Both T3 and T4 are produced in response to TSH from the pituitary gland. T4 circulates mostly bound to plasma proteins, with a small amount unbound and available for biological activity. To estimate free T4 concentration, a total T4 test and T3 uptake test are used to calculate the free T4 index [1].A normal TSH result excludes most cases of primary overt thyroid disease. Therefore, a cascaded testing approach (test code 15102) may be preferable for evaluating and monitoring thyroid function. This panel does not identify T3 thyrotoxicosis, which requires measurement of free T3 [2,3].Note: Interference due to heterophile antibodies has been known to occur [1]. The results of this panel should be interpreted in the context of pertinent clinical and family history and physical examination findings.References1. Demers LM, et al. The thyroid: pathophysiology and thyroid function testing. In: Burtis CA, et al. eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. Elsevier; 2006:2053-2095.2. Ross DS, et al. Thyroid. 2016;26(10):1343-1421.3. Vasileiou M, et al; Guideline Committee. BMJ. 2020;368:m41.
Quest Diagnostics test directory, test code 7444
What the laboratory says this test is for
For diagnosis of hypothyroidism and hyperthyroidism.
Quest Diagnostics test directory, test code 7020
Everything above is drawn from the named sources and shown as they published it. Reference ranges belong to the laboratory that issued them and the population it named; they are not a universal normal. This page describes the biomarker in general and does not interpret anyone's result. For your own numbers, talk to a clinician, or use Aumnivida, which reads the same graph next to your records.
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