CAS number: 


Molecular formula: C16H22N6O4

Molecular weight: 362.4 a.m.u.

Fields of Application
Diagnosis of Pituitary and Thyroid function

Protirelin is also Known as Thyroptropin-releasing Hormone (TRH). TRH stimulates thyroid-stimulating hormone (TSH) secretion from the anterior pituitary. TSH then initiates thyroid hormone (TH) synthesis and release from the thyroid gland.

The concentration of thyroid hormones in the circulation is regulated by an homeostatic feedback loop involving the hypothalamo-pituitary axis. The main effect of thyroid hormones is to reduce the response of the pituitary thyrotrophs to TRH rather than altering the secretion rate of TRH from the hypothalamus. The sensitivity of the thyrotrophs to TRH depends on their intracellular concentration of T3, 80% of which is derived from the intrapituitary conversion of T4 to T3. When circulating concentrations of T4 are low, there is an increase in the number of TRH receptors and in TSH synthesis resulting in an increased TSH response to TRH. The reverse is true in the presence of high circulating concentrations of thyroid hormones. The TSH response to a bolus injection of TRH has been used to diagnose the exact cause of hypo- and hyper-thyroidism.

Regular injectable form.