|Products||TSH IRMA Test|
|Company||Diagnostic Systems Laboratories, Inc.|
|Item||TSH IRMA Test|
|Description|| Thyroid-stimulating hormone (TSH) is a 32 kDa glycoprotein secreted by the thyrotrope cells of the anterior pituitary gland . The structure of human TSH is similar to that of the pituitary and placental gonadotropins, consisting of an a-subunit which is similar or identical between these hormones and a unique beta-subunit, which confers hormonal specificity. TSH stimulates production of thyroid hormones by binding to thyrocyte membrane receptors, leading to stimulation of cAMP-dependent iodine transport and resultant thyroid hormone synthesis . TSH secretion is stimulated by thyrotropin-releasing hormone (TRH) which is secreted by the hypothalamus and is regulated at both the pituitary and hypothalamic levels by thyroid hormones. Low levels of thyroid hormones lead to increased TSH secretion and elevated thyroid hormone levels lead to decreased TSH secretion.
During human fetal life, serum TSH levels are measurable at about 18 weeks gestation and increase to a peak at the beginning of the 3rd trimester. At birth, a sharp and dramatic increase in serum TSH levels occurs with a subsequent rapid decline over several hours . Postnatal secretion of TSH is relatively age- and sex-independent and occurs in a circadian pattern with a nadir in the late afternoon and a peak at approximately midnight. Measurement of serum TSH levels have been used in the diagnostic evaluation and therapeutic monitoring of primary hypo- and hyper-thyroidism. In addition, measurement of TSH levels following parenteral administration of TRH has been used in the evaluation of TSH-deficiency .
|Info|| Diagnostic Systems Laboratories, Inc.|
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