Thyroid Stimulating Hormone (TSH)
METHODOLOGY
Electrochemiluminescence Immunoassay (ECLIA)
PERFORMED
Tuesday & Friday
REPORTED
2 days
COLLECT
One 6mL RT (Min: 4mL RT)
TRANSPORT
1 mL refrigerated serum (Min: 0.5 mL)
STABILITY
Stored at 2 - 8°C until used; Stable if frozen at - 20°C
UNACCEPTABLE SPECIMENS
Do not use heat-inactivated samples.
REFERENCE RANGE
0.30 – 4.0 mIU/L
CPT CODE
84443
INFORMATION
The determination of TSH serves as the initial test in thyroid diagnostic evaluation of ambulatory patients. Even very slight changes in the concentrations of the free thyroid hormones bring about much greater opposite changes in the TSH level. Accordingly, TSH is a very sensitive and specific parameter for assessing thyroid function and is particularly suitable for early detection or exclusion of disorders in the central regulating circuit between the hypothalamus, pituitary and thyroid.
Thyroid-stimulating hormone (TSH, thyrotropin) is a glycoprotein having a molecular weight of approximately 30,000 daltons and consisting of two subunits. The beta-subunit carries the TSH-specific immunological and biological information, whereas the alpha-chain carries species-specific information and has an identical amino acid sequence to the alpha chains of LH, FSH and hCG.
TSH is formed in specific basophil cells of the anterior pituitary and is subject to a circadian secretion sequence. The hypophyseal release of TSH (thyrotropic hormone) is the central regulating mechanism for the biological action of thyroid hormones. TSH has a stimulating action in all stages of thyroid hormone formation and secretion; it also has a proliferative effect.