TSH

TSH Full Name

Thyroid-stimulating hormone

TSH Introduction

The anterior pituitary gland produces thyroid-stimulating hormone (TSH) which also known as thyrotropin. The hormone TSH functions as a glycoprotein to activate thyroid-stimulating hormone receptors (TSHR) on thyroid follicular cells which leads to thyroid hormone production of thyroxine (T4) and triiodothyronine (T3). Thyroid hormones T4 and T3 function as essential regulators of body metabolism and growth and development across all human tissues. The beta subunit of TSH determines its receptor binding properties while the alpha subunit maintains structural integrity. The body controls TSH production through a negative feedback system which responds to T3 and T4 blood levels and receives input from TRH produced by the hypothalamus.

Figure 1. TRH-TSH-T3 feedback loop.(Source: Kim HY, et al. 2013)

The main function of TSH regulates thyroid function which controls various body processes including metabolic rate and heart rate and body temperature and protein production. The TSH signaling pathway through TSHR receptors plays a role in controlling thyroid cell growth and development. The thyroid hormone equilibrium becomes disrupted when TSH or its receptor functions improperly which leads to hypothyroidism or hyperthyroidism. The body produces insufficient thyroid hormones when TSH levels become elevated but thyroid hormone excess or thyroid autonomy causes TSH levels to decrease.

Medical professionals use TSH as their main diagnostic tool to identify and track thyroid-related diseases including Hashimoto's thyroiditis and Graves' disease. The autoimmune disease Graves' disease produces stimulating antibodies which activate TSHR receptors to create hyperthyroidism that produces specific medical symptoms. The loss of negative feedback mechanism in primary thyroid failure leads to elevated TSH levels in hypothyroidism. The measurement of TSH levels helps doctors identify patients who face increased risks of cardiovascular disease and infertility and neurocognitive decline. The assessment of endocrine function requires TSH measurement because it also helps doctors understand metabolic and developmental health effects.

Alternate Names for TSH

HCG; LHA; FSHA; GPHa; TSHA; GPHA1; CG-ALPHA; CGA; TSHB; Thyroid-stimulating hormone, beta; Thyroid-stimulating hormone beta

• 1.Kim HY, et al. Role and Mechanisms of Actions of Thyroid Hormone on the Skeletal Development. Bone Res. 2013, 1(2):146-61.