1. Store the kit at 2-8°C in a refrigerator.
2. Keep microwells sealed in a dry bag with desiccants.
3. The unopened reagents are stable until expiration of the kit. TMB Solution should be colorless; if solutions turn blue, it must be replaced. Do not exp
The thyroid gland produces thyroxine T4, triiodothronine T3 and calcitonin. The first two hormones are synthesized by the gland following entrapment of iodide, conversion to iodine, and coupling of iodine with tyrosine, followed by coupling of two iodinated tyrosine molecules. T4 and T3 so formed are attached to thyroglobulin for storage and are released, as needed, as protease splits them from globulin.
Thyroxine is a highly active thyrometabolic hormone that exists in protein-bound and unbound forms. For T4 can be measured more easily and with greater accuracy than T3, determination of total T4 by immunoassay is the most reliable for detecting thyroid disorders in man.
Release of T4 and T3 from the thyroid is greatly influenced by pituitary-thyroid stimulating hormone (TSH) that in turn is influenced by hypothalamic thyrotropin-releasing hormone (TRH). Normally, increased blood levels of T4 and T3 act to decrease the amount of TSH secreted, thereby reducing the production and release of T4 and T3. Decreaded blood levels of T4 and T3 produce the opposite effect, leading to increased production and secretion of T4 and T3.
In this manner a normal circulating thyroid hormone balance is maintained. Circulating T4 and T3 are bound largely to thyroxine binding globulin (TBG). To a lesser extent they are bound to thyroxine binding prealbumin (TBPA) and, when present in excess, to albumin. Usually T4 to T3 concentration ratio is about 9:1, However T3 has considerably greater physiological activity. It is the small free fraction (0.1% of the total or less) that is physiologically active and determines the clinical thyroid status of the patient's hyperthyroid, euthyroid, or hypothyroid.