Thyrotropin (Thyroid Stimulating Hormone)
Thyrotropin alfa (recombinant human TSH)
Also known as: Thyrogen · Ambinon · Thyreostimulin · Thytropar · Thyroid-stimulating hormone · Thyrotrophic hormone · rhTSH · Recombinant human thyrotropin
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| TSH stimulation test | 75 micrograms (total dose) | IV | Once | — | 🌎 NA |
| TSH stimulation test | 50-100 micrograms (0.05-0.1 mg) | IV | Once | — | 🌎 NA |
| TSH stimulation test | 50-150 μg/dog | IV | single dose | 1 day | 🌍 EU |
- TSH stimulation test: Blood samples taken before and 6 hours after rhTSH administration for determination of total serum thyroxine (T4) concentration.
- TSH stimulation test: Measure serum T4 at 0 hours (pre-sample) and 4 hours post. Product may be frozen for at least 8 weeks with no loss of potency.
- TSH stimulation test: Higher doses offer increased discriminatory power in dogs with comorbidities or those receiving thyroid-suppressing drugs.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| TSH stimulation test | 25 μg/cat | IV | single dose | 1 day | 🌍 EU |
- TSH stimulation test: The diagnostic value in cats has not been fully assessed.
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| TSH stimulation test | 1 Unit/kg | IM | Once | — | 🌎 NA |
- TSH stimulation test: Draw pre-dose baseline sample. Collect sample for T4 6 hours after dose.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Thyrotropin (TSH) is a glycoprotein hormone used in veterinary medicine principally as a diagnostic agent in the TSH stimulation test to diagnose primary hypothyroidism.
- Historical Use: Formerly available as a bovine-source veterinary product (Dermathycin®) for treating acanthosis nigricans and temporary supportive therapy in hypothyroidism.
- Current Practice: The commercially available product is now derived from human sources via DNA recombinant technology (rhTSH). It is highly purified and preferred over older animal-derived products due to better availability and standardized potency.
- Clinical Pearl: The TSH stimulation test is considered the gold standard for evaluating thyroid reserve and confirming a diagnosis of hypothyroidism when basal T4 and endogenous canine TSH concentrations are equivocal.
Mechanism of action
Thyrotropin binds to TSH receptors on the basolateral membrane of thyroid follicular cells. This binding activates the adenylate cyclase/cAMP pathway, which stimulates multiple steps in thyroid hormone synthesis:
- Increases iodine uptake (trapping) by the thyroid gland.
- Stimulates the iodination of tyrosine residues on thyroglobulin.
- Increases the production and secretion of active thyroid hormones (T3 and T4) into the systemic circulation.
With prolonged use, hyperplasia of thyroid cells may occur, though this is not a concern with single-dose diagnostic use.
Safety & warnings
Contraindications
- Adrenocortical insufficiency (untreated Addison's disease)
- Hyperthyroidism
- Coronary thrombosis
- Hypersensitivity to bovine thyrotropin or human proteins
- Repeated administration is not advisable
- Patients currently receiving levothyroxine therapy
- Use of chemical grade TSH (due to anaphylaxis risk)
Adverse effects
- Hypersensitivity reactions (especially with repeated injections of human-derived proteins in animals)
- Clinical signs of hyperthyroidism (with chronic administration or high doses)
- Anaphylactic responses (specifically associated with chemical grade/bovine TSH; recombinant forms are generally well tolerated)
Precautions
Hypersensitivity Warning: Because the commercially available product is derived from human sources, hypersensitivity reactions may occur in patients sensitive to human proteins, particularly with repeated use.
- Pregnancy: FDA Category C. Animal studies have shown an adverse effect on the fetus, but there are no adequate studies in humans.
- Nursing: Unknown if excreted in milk, but unlikely to be clinically significant when used for a one-time diagnostic test.
Drug interactions
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May decrease serum T4 levels, making the TSH stimulation test hard to interpret
May cause T4 levels to be increased, making the TSH stimulation test hard to interpret
May cause T4 levels to be increased, making the TSH stimulation test hard to interpret
May cause T4 levels to be increased, making the TSH stimulation test hard to interpret
May cause T4 levels to be increased, making the TSH stimulation test hard to interpret
May cause T4 levels to be increased, making the TSH stimulation test hard to interpret
Monitoring
- Serum total T4 concentrations (baseline and 4-6 hours post-administration)
- Clinical signs of hypersensitivity or anaphylaxis during and immediately after administration
- Serum total T4 levels (baseline and post-stimulation, typically 4-6 hours post-injection)
Pharmacokinetics
Absorption
Exogenously administered TSH apparently exerts maximal increases in circulating T4 approximately 4-8 hours after IM or IV administration.
Metabolism
Degraded primarily in the kidneys and liver.
Elimination
Cleared via renal and hepatic pathways.
Overdose
Chronic administration at high dosages can produce clinical signs of hyperthyroidism (e.g., weight loss, polyphagia, tachycardia, hyperactivity).
Massive overdoses can cause clinical signs resembling thyroid storm (a life-threatening hypermetabolic state). Treatment is generally supportive and symptomatic; refer to levothyroxine overdose protocols for specific management strategies.
Available products
Formulations
- Lyophilized powder for injection
- Injectable: 1.1 mg vial (yields 0.9 mg/ml after reconstitution with 1.2 ml sterile water)
Human-labeled
- Recombinant (human) Thyrotropin (Thyroid Stimulating Hormone) Powder for Injection, Lyophilized: 1.1 mg per vial; Thyrogen® (Genzyme); (Rx)
- Thyrogen 1.1 mg powder for injection
Regulatory status
Human approved drug (Thyrogen) used off-label under the cascade.
Human approved drug (Thyrogen) used off-label under the cascade.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Unreconstituted thyrotropin alfa should be stored between 2-8°C (36-46°F). Reconstituted solution can be stored up to 24 hours between 2-8°C (36-46°F), avoiding microbial contamination. It is reportedly stable if kept refrigerated (2-8°C) up to 4 weeks and up to 8 weeks if frozen (-20°C). Protect from light. Visually inspect each vial for particulate matter or discoloration before use; do not use if present.
Client information
Thyrotropin is used as a one-time diagnostic test to evaluate how well your pet's thyroid gland is functioning.
- The Procedure: Your pet will have a baseline blood sample drawn, receive an injection of the hormone, and then stay at the clinic (or return) for a second blood draw 4 to 6 hours later.
- Safety: Because this is a human-derived protein, there is a very small risk of an allergic reaction. Let your veterinarian know immediately if you notice facial swelling, hives, vomiting, or difficulty breathing after the test.
- Cost: The human recombinant product can be expensive, which may factor into the overall cost of the diagnostic workup.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.