TSH Fast Test Kit (Immunofluorescence Assay) Is intended for in vitro quantitative determination of thyroid-stimulating hormone (TSH) in serum and plasma. This test is used in the screening, clinical diagnosis, prognosis and therapeutic effect evaluation of thyroid diseases. Sumamry: TSH is the main regulator of thyroid cell growth, thyroid hormone synthesis and secretion. TSH (MW 30 kDa) is synthesized and secreted by tsh cells of pituitary gland, it has negative feedback to the synthesis and secretion process. The fluctuation of TSH is faster and more significant than thyroid hormones when thyroid function was changed, it is a sensitive biomarker of hypothalamic-pituitary-thyroid function.