Peptide reference
TRH (Protirelin)
Protirelin ·Thyrotropin-releasing hormone ·TRH ·Relefact TRH ·Thypinone ·pyroGlu-His-Pro-NH2
What cited sources report about TRH (protirelin)
Thyrotropin-releasing hormone (TRH; protirelin) is an endogenous hypothalamic tripeptide (pyroGlu-His-Pro-NH2) that drives pituitary TSH and prolactin release. The synthetic peptide was historically approved in the US as Thypinone and Relefact TRH for the diagnostic TRH stimulation test in pituitary-thyroid disease. Cited DailyMed records do not return an active US human-finished-drug NDA label for protirelin as of this writing; current returns are bulk-API and animal-drug entries. Outside the US, protirelin remains marketed in some jurisdictions (notably Japan) for spinocerebellar-degeneration indications. The summaries below report what individual cited sources state; this page does not assert claims beyond what those sources report.
Fröhlich and Wahl (2019) — Frontiers in Neuroendocrinology
A review examined TRH biology beyond hypothalamic-pituitary-thyroid feedback regulation and characterized current therapeutic use as restricted. The authors noted spinocerebellar degenerative disease as the most cited active indication in jurisdictions where the formulation remains marketed and discussed energy-metabolism, prolactin-secretion, and possible cancer-biomarker roles. They also observed that the peptide’s rapid plasma degradation is a structural constraint on systemic therapy.
Regulation of TRH production in the hypothalamus, patterns of expression of TRH and its receptor in the body, its role in energy metabolism and in prolactin secretion are addressed in this review.
Atmaca et al. (2007) — Thyroid
A study from Erciyes University evaluated the TRH stimulation test in 72 Sheehan’s syndrome patients. The investigators reported that 91.6% of the cohort had central hypothyroidism and that 13.8% of cases would have been missed by basal fT4 and TSH measurement alone. The authors concluded that the TRH stimulation test retains a useful role in central hypothyroidism diagnosis when basal indices are low-normal in patients with known hypothalamic-pituitary pathology.
TRH stimulation test is useful in the diagnosis of central hypothyroidism, especially in whom fT(4) and/or TSH is low-normal and known to have hypothalamo-pituitary pathology.
DailyMed — National Library of Medicine
A DailyMed search for “protirelin” returns predominantly bulk active-pharmaceutical-ingredient powders intended for compounding and animal-drug entries; no current US human-finished-drug NDA label corresponding to the historic Thypinone or Relefact TRH brands appears active in the result set as of this writing.
PubChem CID 638678 — National Center for Biotechnology Information
The PubChem compound record for protirelin lists molecular formula C16H22N6O4, consistent with the tripeptide pyroGlu-His-Pro-NH2 identical to the endogenous thyrotropin-releasing hormone. The record aggregates synonyms — including TRH, Relefact, and Thypinone — and links to underlying chemical and pharmacological literature.
Coverage notes
TRH is a historically approved US human drug (Thypinone, Relefact TRH) whose finished-drug labels are not active in the cited DailyMed result set. This page therefore records fda_approval: withdrawn for the US human market while recognizing that the substance remains approved in some non-US jurisdictions for spinocerebellar-degeneration indications (the Fröhlich and Wahl review notes restricted current therapeutic use). Compounded protirelin remains accessible through 503A pathways. Anyone relying on TRH for diagnostic stimulation testing or therapy should consult current FDA Orange Book and DailyMed records directly.