Thyroid related
Thyrotropin releasing hormone (TRH)

Author: Nat Pernick, M.D. (see Authors page)

Revised: 23 February 2016, last major update March 2011

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Thyrotropin releasing hormone [title]
Cite this page: Thyrotropin releasing hormone (TRH). website. Accessed May 22nd, 2018.
Definition / general
  • Also called thyrotropin releasing factor
  • Produced by hypothalamus
  • Enhances TSH synthesis and stimulates its secretion
  • Also affects prolactin, and other pituitary hormones to a lesser extent
  • Also produced in pancreatic beta cell, where it colocalizes with insulin, highest levels in neonates (Acta Biomed 2007;78:216)
  • Feedback inhibition due to circulating T3 and T4
  • Regulated also by leptin, which mediates food appetite
  • Resistance occurs rarely (OMIM - TRHR)
  • Methodology:
    • Can measure by RIA but specimen must be frozen
    • TRH stimulation test:
      • Measure baseline TSH
      • Give IV bolus of TRH
      • Measure TSH (should rise within 5 minutes, peak in 20 minutes)
        • "Fold increase" is a better measure of response than absolute increase
  • Exaggerated: primary hypothyroidism
  • Suppressed: hyperthyroid patients (including Graves disease), also multinodular goiter, renal failure, Cushing syndrome, depression, drugs
  • No response: pituitary disorder (may not be necessary for diagnosis, J Clin Endocrinol Metab 2003;88:5696)