24 AFIAS test cassettes for the quantitative determination of total thyroxine (total T4) in human serum or plasma.
Package contents:
24 AFIAS test cassettes
24 pipette tips
1 ID chip
1 package insert
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The AFIAS T4 test is a fluorescence immunoassay (FIA) for the quantitative determination of total thyroxine (total T4) in human serum and plasma. The test is used as an aid in the treatment and monitoring of thyroid disorders. For in vitro diagnostic use only.
Thyroxine (T4) is one of the two main hormones produced by the thyroid gland (the other is triiodothyronine, T3). T4 and T3 are regulated by a sensitive feedback system that also involves the hypothalamus and pituitary gland. The hypothalamus releases thyrotropin-releasing hormone (TRH), which in turn stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). The thyroid gland then releases T3 and T4, which in turn regulate the release of TRH and TSH through a negative feedback mechanism. Normally, increased T4 and T3 levels in the blood reduce the amount of TSH released, which in turn reduces the production and release of T4 and T3. Over 99% of T4 hormone is reversibly bound in the blood to three plasma proteins: Thyroxine-binding globulin (TBG) binds almost 70 %, thyroxine-binding prealbumin (TBPA) binds 20 % and albumin 10 %. About 0.03 % T4 always circulates in the blood in a free, unbound state. T4 is a helpful marker in the diagnosis of hyperthyroidism and hypothyroidism. In hypothyroidism, myxoedema and chronic thyroiditis (Hashimoto's thyroiditis), T4 levels decrease. Elevated T4 levels have been found in hyperthyroidism caused by Grave's disease and Plummer's disease.
