Thyroid-stimulating hormone

The (i.e., chorionic gonadotropin alpha) is nearly identical to that of human chorionic gonadotropin (hCG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). The α subunit is thought to be the effector region responsible for stimulation of adenylate cyclase (involved the generation of cAMP).^[10] The α chain has a 92-amino acid sequence.

The β (beta) subunit () is unique to TSH, and therefore determines its receptor specificity.^[11] The β chain has a 118-amino acid sequence.

antibodies (which include human anti-mouse antibodies (HAMA) and Rheumatoid Factor (RF)), which bind weakly to the test assay's animal antibodies, causing a higher (or less commonly lower) TSH result than the actual true TSH level.^[21][22] Although the standard lab assay panels are designed to remove moderate levels of heterophilic antibodies, these fail to remove higher antibody levels. "Dr. Baumann [from Mayo Clinic] and her colleagues found that 4.4 percent of the hundreds of samples she tested were affected by heterophile antibodies.........The hallmark of this condition is a discrepancy between TSH value and free T4 value, and most important between laboratory values and patient's conditions. Endocrinologists, in particular, should be on alert for this."

Macro-TSH - endogenous antibodies bind to TSH reducing its activity, so the pituitary gland would need to produce more TSH to obtain the same overall level of TSH activity.

TSH - natural variations of the TSH molecule, which have lower activity, so the pituitary gland would need to produce more TSH to obtain the same overall level of TSH activity.^[24][25]

The same TSH concentration may have a different meaning whether it is used for diagnosis of thyroid dysfunction or for monitoring of substitution therapy with . Reasons for this lack of generalisation are Simpson's paradox^[26] and the fact that the TSH-T3 shunt is disrupted in treated hypothyroidism, so that the shape of the relation between free T4 and TSH concentration is distorted.^[27]

TSH at

: 003684

at the U.S. National Library of Medicine Medical Subject Headings (MeSH)