TRH
protirelin, thyrotropin-releasing hormone, TRF, Thyrel TRH, Thypinone
REC PPT-TRH-THYROTROPIN // REV 2026-10-04 // assessment changes are logged, never silent
The compound sold as research TRH is protirelin, a synthetic tripeptide that the FDA approved decades ago purely as a pituitary diagnostic; both approved US products are discontinued, and the enormous publication count attached to the name belongs to the endogenous hormone, not to the product.
What it is
Thyrotropin-releasing hormone is a hypothalamic tripeptide, pyroglutamyl-histidyl-prolinamide. Its synthetic form is protirelin. Administered intravenously it prompts the anterior pituitary to release thyroid-stimulating hormone, and prolactin alongside it.
What it does
Approved and used as a diagnostic agent to probe anterior pituitary reserve in suspected thyroid or pituitary disorders. It was also investigated in amyotrophic lateral sclerosis, depression, spinal cord injury and schizophrenia, none of which produced an approved indication.
Does it work?
This is the record where the raw number is most misleading. The 21,707 indexed publications and 226 randomised controlled trials counted on 2026-08-25 are the literature of the endogenous hormone and of the TRH stimulation test as a physiological tool — neuroendocrinology, thyroid-axis regulation, animal work — not evidence for any research-peptide product bearing the name. Reading that count as backing for a product is the single most common error made about this compound. What is genuinely established is narrow and diagnostic: a single intravenous administration produces a reproducible TSH and prolactin rise, which is exactly what the discontinued FDA labels covered. The therapeutic programmes that once ran in ALS, depression and spinal cord injury did not yield an approved indication in any of those conditions.
Claims vs data
Each marketing claim, tagged by what the evidence actually supports.
| A single intravenous administration produces a measurable rise in thyroid-stimulating hormone | supported |
| It raises circulating prolactin as well as TSH | supported |
| Produces transient mood elevation in small controlled studies in depression | weak evidence |
| Restores thyroid function, metabolic rate or energy in people with a normal thyroid axis | overreach |
Reference figures
Quoted from published reference material. These are not Peptuity recommendations.
molecular data — PubChem CID 638678
The evidence, counted
Live counts from Europe PMC and ClinicalTrials.gov.
269 publications indexed, but only 15 randomised controlled trials and 18 registered interventional studies. Human evidence exists but is thin.
SRC // EUROPE PMC + CTGOV // "protirelin" // FETCHED 2026-10-04 // 269 RECORDS
Most-cited literature
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[01]
G Protein-Coupled Receptors as Targets for Approved Drugs: How Many Targets and How Many Drugs?
Sriram K, Insel PA. · Mol Pharmacol 2018 · 1056 citations · DOI 10.1124/mol.117.111062
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[02]
Peptide-like and small-molecule inhibitors against Covid-19
Pant S, Singh M, Ravichandiran V, Murty USN, Srivastava HK. · J Biomol Struct Dyn 2021 · 212 citations · DOI 10.1080/07391102.2020.1757510
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[03]
Colon targeted drug delivery systems: a review on primary and novel approaches
Philip AK, Philip B. · Oman Med J 2010 · 173 citations · DOI 10.5001/omj.2010.24
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[04]
Thyroid dysfunction in adults over age 55 years. A study in an urban US community
Bagchi N, Brown TR, Parish RF. · Arch Intern Med 1990 · 141 citations · DOI 10.1001/archinte.1990.00390160053012
Regulatory status
Formal, dated regulatory actions.
US FDA — discontinued 2026-08
Thyrel TRH (protirelin 0.5 mg/mL, Ferring), application NDA 018087, originally approved 18 July 1978 as a diagnostic agent. Listed as Discontinued in Drugs@FDA.
US FDA — discontinued 2026-08
Thypinone (protirelin 0.5 mg/mL, Abbott), application NDA 017638, originally approved 5 November 1976. Listed as Discontinued in Drugs@FDA. With both applications discontinued, no FDA-approved protirelin product is marketed in the United States.
Common questions
Does the publication count mean TRH is well studied as a product?
No, and this is the central point. Searching the hormone name returns the whole neuroendocrinology literature of an endogenous human hormone. Those papers describe how the body's own TRH works; they are not trials of an administered research peptide and cannot be counted as evidence for one.
Was protirelin FDA approved?
Yes, as a diagnostic. Thypinone (Abbott, NDA 017638) was approved on 5 November 1976 and Thyrel TRH (Ferring, NDA 018087) on 18 July 1978. Both appear as Discontinued in the FDA Drugs@FDA database, so no approved protirelin product is marketed in the United States today.
What was the approved indication?
Diagnostic only — assessing anterior pituitary TSH reserve in suspected thyroid or pituitary disease. The approval was for a single administration in a controlled clinical setting with blood sampling, not for repeated administration and not for any therapeutic purpose.
Is it prohibited in sport?
Protirelin and thyrotropin-releasing hormone were not located on the WADA 2026 Prohibited List, and no WADA code could be confirmed for them. That is a statement about what could be verified, not a clearance. Athletes should confirm current status directly with WADA or their national anti-doping organisation.
Related compounds
Gonadorelin
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Sermorelin
GHRH fragment with a long clinical history, once used diagnostically.
Tesamorelin
Approved GHRH analogue for HIV-associated lipodystrophy — a narrow, real indication.
Kisspeptin-10
Key reproductive-axis regulator with real academic research behind it.