Protirelin (TRH)
Thyrotropin-releasing hormone — an approved diagnostic agent, discontinued since 2002.
For research purposes only. These products are not intended to diagnose, treat, cure, or prevent any disease. By purchasing, you confirm these products will be used for legitimate research purposes.
About Protirelin (TRH)
Protirelin is synthetic thyrotropin-releasing hormone, a tripeptide that stimulates TSH release from the anterior pituitary. Its FDA approval is narrow and specific: an adjunct in the diagnostic assessment of thyroid function, useful in patients with pituitary or hypothalamic dysfunction and for checking whether a given levothyroxine dose is adequately suppressing thyrotropin in nodular or diffuse goitre. It was never approved as a treatment for anything. Production of the only FDA-approved TRH preparation stopped in July 2002. It is also unusually symptomatic for a diagnostic agent. The label reports side effects in about half of all patients tested — typically brief and mild, resolving within minutes of injection, but including marked blood pressure changes in both directions, with syncope in a small number of patients. The diagnostic dose was a single 500 microgram intravenous bolus, which is worth comparing against the 20mg and 50mg research vials on sale.
Key Benefits
- Well-defined approved diagnostic role in thyroid and pituitary assessment
- Distinguishes pituitary from hypothalamic dysfunction
- Effects appear and resolve within minutes
- Extensively characterised endocrine pharmacology
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Category Ratings
How to Take
Common Side Effects
- Side effects reported in roughly 50% of patients tested — usually brief
- Nausea
- Urge to urinate
- Flushed sensation and light-headedness
- Bad taste in the mouth and dry mouth
- Marked blood pressure changes — hypertension or hypotension, with syncope in a small number of patients
- Convulsions, rarely, in patients with epilepsy or brain damage
- Transient loss of vision in patients with pituitary tumours
Legal & Regulatory Status
FDA-approved only as an adjunctive DIAGNOSTIC agent for thyroid function assessment — never as a treatment. Production of the only FDA-approved preparation ceased in July 2002, so no approved product is currently marketed.
Safety and regulatory details for FDA-approved compounds are drawn from the official product label via openFDA; clinical development status reflects ClinicalTrials.gov. This information is provided for research reference, is not endorsed by the FDA, and may not be complete or current.
Research & Sources
- Thyrotropin Releasing Hormone (TRH) — FDA label: diagnostic indication, adverse reactions in ~50% (DailyMed)
- Diagnostic dosages of protirelin (TRH) elevate blood pressure by noncatecholamine mechanisms (PMID 6428340)
Sources are selected for reliability (peer-reviewed literature, openFDA, ClinicalTrials.gov) but this is a research summary, not medical advice, and may not be exhaustive.
Prices at quality-checked sources · as of August 2026 (8 days ago)
- 20mg $100.9750mg $221.08
Observed on each vendor’s public listing — see how these sources are vetted. Peptide Concierge doesn’t sell peptides and isn’t affiliated with any vendor; confirm current pricing at the source.
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