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Thyrotropin-Releasing Hormone (TRH)

Also known as Protirelin, TRH, Thyrotropin TRH, L-pyroglutamyl-L-histidyl-L-proline amide, Relefact

Protirelin, the hypothalamic tripeptide that triggers pituitary TSH release; an approved diagnostic agent with a very short half-life.

Molecular weight362.39 g/mol
Half-lifeVery short — approximately 5 minutes in blood after IV administration.
CategoryOther

Typical use cases

✓ Pituitary-thyroid axis diagnostic testing✓ Prolactin-axis research✓ Neuromodulation/arousal research✓ Neuroprotection studies

Dosing guidelines

StartingClinical diagnostic use: 200–500 mcg IV (single dose). No standardized chronic research dose.
MaintenanceNot applicable for diagnostic use; any repeated research dosing is unvalidated.
Max (studied)Hedge — diagnostic dosing is typically a single 500 mcg IV bolus; higher/repeated dosing is not standardized.

Titration

Typically flat-dosed (single diagnostic bolus); no titration scheme.

Reconstitution

25 mg vial: ~2.5 mL bacteriostatic water yields ~10 mg/mL (note that clinical doses are in micrograms).

Injection sites

Clinically administered intravenously as a bolus; research forms have also been explored intranasal/oral. Subcutaneous self-handling is non-standard.

Storage & handling

Lyophilized: stable months cool/dark, longer frozen. Reconstituted: refrigerate (2–8 °C).

Side effects

  • Transient urge to urinate Mild · Common
  • Nausea Mild · Common
  • Flushing / warmth Mild · Common
  • Transient blood-pressure change Moderate · Uncommon
  • Lightheadedness Mild · Uncommon

Research summary

TRH (protirelin) is the endogenous tripeptide pyroglutamyl-histidyl-proline amide that stimulates the anterior pituitary to release thyroid-stimulating hormone (TSH) and prolactin, and is an approved diagnostic agent for assessing pituitary-thyroid axis function. Beyond endocrinology, TRH has documented central/arousal effects and is studied for neuroprotective signaling, but its extremely short half-life limits systemic use. IV administration commonly causes brief, self-limited effects such as a transient urge to urinate, nausea, flushing and transient blood-pressure changes. Educational only — not medical advice.

Key references

  • Thyrotropin-releasing hormone (protirelin) — Drugs.com prescribing information
  • Structural insights into TRH receptor activation, PMC (2022)

Related compounds

Gonadorelin → Sermorelin →

Where to buy

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Educational reference only — not medical advice. Dosing figures are commonly-cited ranges, not prescriptions. Consult a qualified clinician.

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