Thyrotropin alfa
Recombinant human TSH for thyroid cancer testing and radioiodine ablation
Thyrotropin alfa is recombinant human thyroid-stimulating hormone, sold as Thyrogen. Two injections a day apart stimulate any remaining thyroid tissue so doctors can test and treat thyroid cancer without taking patients off thyroid hormone for weeks.
Manufacturer's recommended dosing (FDA label): 0.9 mg, then a second 0.9 mg, Two injections 24 hours apart, Intramuscular, into the buttock (never intravenous) Details ↓
Recommended Dosing
Manufacturer's recommended dosing (FDA label)
From the prescribing information. Other doses studied, if any, are in the full dosing data below.
What is it?
After surgery for well-differentiated thyroid cancer, the usual follow-up asks one question: is any thyroid tissue or cancer left? Thyroid cells take up iodine and release thyroglobulin when thyroid-stimulating hormone (TSH) is high, so radioiodine scans and thyroglobulin blood tests work best with high TSH. The old way to raise it was to stop thyroid hormone for several weeks, leaving patients hypothyroid, with the symptoms and low mood its first phase 3 trial measured.
Thyrotropin alfa raises TSH from the outside. It is recombinant human TSH, a glycoprotein of two subunits made in Chinese hamster ovary cells with the same amino-acid sequence as the pituitary hormone. It is a large protein hormone, related to the small peptides on this site only by family, and it is a diagnostic and treatment adjunct given by thyroid specialists, not a peptide for personal use. The FDA approved it as Thyrogen in 1998 for thyroglobulin testing with or without radioiodine imaging, and later as an adjunct to radioiodine ablation of thyroid remnants.
Its trials compared it with hormone withdrawal in the same patients. In the first phase 3 study, scans after Thyrogen agreed with withdrawal scans in 83% of patients but missed some disease, and patients felt far better. In the second, scans agreed in 89%, and combining the scan with a stimulated thyroglobulin test detected disease in 93% of patients with tissue in the thyroid bed and all with metastases. The label warns that Thyrogen-stimulated thyroglobulin runs lower than after withdrawal and that disease can still be missed.
For ablation, an international randomised trial found the same success with Thyrogen as with withdrawal, better quality of life and about a third less radiation dose to the blood. The UK HiLo trial of 438 patients then showed that a low radioiodine activity with Thyrogen worked as well as a high one, with fewer side effects and shorter hospital stays. A Japanese surveillance study of more than 9,000 patients found adverse reactions in 7.1%, mainly nausea.
The label's warnings matter for anyone with thyroid tissue still in place or with metastases: Thyrogen can cause a temporary rise in thyroid hormone, deaths have been reported within 24 hours in people who had not had their thyroid removed or had distant metastases, and metastases can swell suddenly and painfully. Strokes have been reported, mostly in young women taking oral contraceptives. It has also been studied to boost radioiodine treatment of large goitres, where it shrank goitres more but caused more hypothyroidism; that is not a US-labelled use.
Mechanism of Action
Thyrotropin alfa acts like the body's own TSH on thyroid cells (Thyrogen label 12.1).
TSH receptor
Binds TSH receptors on normal thyroid cells and well-differentiated thyroid cancer (label 12.1).
Iodine uptake
Stimulates iodine uptake, so radioiodine can show or destroy remaining thyroid tissue (label 12.1).
Thyroglobulin release
Makes thyroid cells release thyroglobulin, the tumour marker measured in blood 72 hours after the last dose (label 12.1, 2.3).
Published Research
The studies behind thyrotropin alfa, read from their PubMed abstracts: the diagnostic and ablation trials against thyroid hormone withdrawal, dosimetry, and safety.
First use in thyroid cancer patients
In 19 patients after thyroidectomy, intramuscular rhTSH raised TSH within 2 to 8 hours and allowed radioiodine scans while on thyroid hormone; scans matched hypothyroid scans in 63%, each method found lesions the other missed in 16%, nausea occurred in 16%, and quality of life was far better.
Phase 3: scans against withdrawal
In 127 patients scanned after two doses of recombinant TSH and again after stopping thyroid hormone, the scans agreed in 83%; among positive scans the withdrawal scan was better in 29%, and patients had far fewer hypothyroid symptoms and mood problems with recombinant TSH.
Phase 3: scans plus thyroglobulin
In 229 patients, scans after recombinant TSH and after withdrawal agreed in 89%; combining the scan with a stimulated thyroglobulin of 2 ng/mL or more detected tissue or cancer in 93% of patients with disease in the thyroid bed and 100% with metastases.
Remnant ablation without hypothyroidism
In an international randomised trial, ablation with 3.7 GBq of radioiodine succeeded in every patient prepared either way; patients kept on thyroid hormone with rhTSH had better quality of life and about a third less radiation to the blood.
Radiation dose to the blood
In 63 patients in the same trial, radioiodine stayed longer in remnant tissue after rhTSH (effective half-time 67.6 against 48.0 hours), and the dose absorbed by the blood was lower (0.109 against 0.167 mGy/MBq).
Quality of life during ablation
In 74 randomised patients, quality of life fell during the hypothyroid preparation but held steady with rhTSH; ablation success judged by thyroglobulin was 91.7% with rhTSH and 97.1% with withdrawal, and small persistent remnants were more common after rhTSH.
HiLo: low-dose radioiodine with thyrotropin alfa
In 438 UK patients, ablation succeeded in 87.1% after thyrotropin alfa and 86.7% after withdrawal, and low-dose radioiodine was non-inferior to high-dose; adverse events were 23% against 30% (not significant), and low doses meant shorter hospital stays.
Low against high radioiodine activity
Pooling three randomised trials (637 patients) prepared with rhTSH, low radioiodine activity ablated thyroid remnants as often as 3.7 GBq and caused fewer side effects such as neck pain, gastritis and salivary problems.
Cochrane review of rhTSH-aided treatment
Four trials of 223 patients found no difference in ablation success between rhTSH and withdrawal, lower radiation to blood and bone marrow with rhTSH, and no deaths or serious adverse effects; there were too few data for metastatic disease.
A Chinese recombinant TSH, SNA001
In 307 Chinese patients with mostly intermediate-risk thyroid cancer, a recombinant human TSH made in China (SNA001, not Thyrogen), 0.9 mg on two days, was non-inferior to withdrawal for ablation (43.8% against 47.1% success) and caused fewer adverse events (29.9% against 58.8%).
Cochrane review: goitre treatment
In six trials (321 participants) with non-toxic multinodular goitre, rhTSH before radioiodine shrank the thyroid by about 12% more but raised the risk of hypothyroidism to 32.5% from 12.1%; quality-of-life data were sparse. This is not a US-labelled use.
Post-marketing study in Japan
Among 9,268 Japanese patients, adverse drug reactions occurred in 7.1%, most often nausea (4.0%); 99.0% of scans were readable, and ablation was judged successful in 81.2% of those assessed.
Dosing Data
Thyrogen is a two-injection regimen given by physicians experienced in thyroid cancer. The label's dose and timing are below.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
The approved product, as its label describes it:
- Thyrogen (thyrotropin alfa injection and kit): For injection: 0.9 mg of thyrotropin alfa as a lyophilized powder in a single-dose vial. Forms the label lists: single-dose vials.
Source: Thyrogen (thyrotropin alfa injection and kit) label, section 3 (DailyMed version 20, effective February 24, 2023).
Mixing a vial: a worked example
The approved product Thyrogen (thyrotropin alfa injection and kit) is a powder that is mixed before use, with the liquid and volume its label names. Follow the label, not a general example. Its label says: “Withdraw 1 mL of the reconstituted THYROGEN solution (0.9 mg of thyrotropin alfa) and inject intramuscularly in the buttocks.”
Source: Thyrogen (thyrotropin alfa injection and kit) label, sections 2 and 3 (DailyMed version 20, effective February 24, 2023).
Storage before and after mixing
Before mixing or first use: “Store THYROGEN refrigerated at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light.”
After mixing or first use: “The reconstituted THYROGEN solution must be injected within 3 hours unless refrigerated.” “If necessary, the reconstituted solution can be stored refrigerated at a temperature between 2°C and 8°C (36°F to 46°F) for up to 24 hours, while avoiding microbial contamination.” “Discard any unused portions.”
Source: Thyrogen (thyrotropin alfa injection and kit) label, sections 16 and 2 (DailyMed version 20, effective February 24, 2023).
How it is taken
As the approved label gives it: Intramuscular, into the buttock (never intravenous) (Two injections 24 hours apart; Label: thyroglobulin testing, radioiodine imaging or remnant ablation).
Source: Manufacturer's recommended dosing (FDA label): the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: a half-life of about 25 hours. After about five half-lives almost none is left.
How long the doses were given: Label: thyroglobulin testing, radioiodine imaging or remnant ablation: Radioiodine 24 hours after the second injection; thyroglobulin sample 72 hours after it.
When effects appear: unknown; no source on this page gives a time to effect for Thyrotropin alfa. Results reported in the studies are under Published Research.
Source: half-life: Thyrogen prescribing information, section 12.3 (DailyMed set b52dfa36, version 20, effective February 24, 2023); Manufacturer's recommended dosing (FDA label), the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Nausea, the commonest effect, and headache; Far fewer hypothyroid symptoms than thyroid hormone withdrawal; More hypothyroidism when used before radioiodine for goitre. Full list and cautions ↓
When to stop or get help: unknown; the label's warnings summary we read gives no rule for stopping Thyrotropin alfa. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the studies above”).
Interactions
Unknown: a PubMed search for human interaction studies of Thyrotropin alfa (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Thyrotropin alfa products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: FDA Approved (FDA-approved November 30, 1998 as Thyrogen (BLA020898, Genzyme), a prescription product in Drugs@FDA). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the studies above.
Contraindications & Cautions
Warnings from the Thyrogen label (DailyMed set b52dfa36, version 20, effective February 24, 2023).
Legal Status
Thyrotropin alfa is an approved prescription biologic in the US.
Frequently Asked Questions
?What is thyrotropin alfa used for?
To raise TSH in people treated for well-differentiated thyroid cancer, so thyroglobulin tests, radioiodine scans or radioiodine ablation of thyroid remnants can be done without stopping thyroid hormone.
?Is it a peptide?
It is a large glycoprotein hormone of two protein subunits, identical in sequence to human pituitary TSH. It is a prescription diagnostic, not a research peptide.
?Is it as accurate as stopping thyroid hormone?
Close but not identical. Scans agreed in 83% to 89% of patients in its trials, and the label says stimulated thyroglobulin runs lower and disease can be missed.
?How is it given?
Two 0.9 mg injections into the buttock muscle 24 hours apart. Radioiodine follows 24 hours after the second, and blood for thyroglobulin is drawn 72 hours after the last injection.
?What are the risks?
Usually nausea or headache. In people with thyroid tissue or metastases still present it can raise thyroid hormone or make tumours swell, and rare strokes have been reported.
?Can it be used for goitre?
It has been studied before radioiodine for large goitres, where it shrank them more but caused more hypothyroidism. That use is not on the US label.
References
- [clinical-trial] Tan H, et al. "Recombinant Human Thyrotropin Plus Radioactive Iodine Among Patients With Thyroid Cancer: A Noninferiority Randomized Clinical Trial." JAMA Netw Open, 2024;7(11):e2443407. PMID: 39509132.
- [review] Huo Y, et al. "Recombinant human thyrotropin (rhTSH)-aided radioiodine treatment for non-toxic multinodular goitre." Cochrane Database Syst Rev, 2021;12(12):CD010622. PMID: 34961921.
- [fda] Drugs@FDA (openFDA): BLA020898, THYROGEN (thyrotropin alfa), Genzyme; original approval November 30, 1998; marketing status Prescription. Read October 28, 2026.
- [fda-pi] Thyrogen (thyrotropin alfa) for injection, US prescribing information, Genzyme. DailyMed set b52dfa36, version 20, effective February 24, 2023; read October 28, 2026.
- [clinical-trial] Meier CA, et al. "Diagnostic use of recombinant human thyrotropin in patients with thyroid carcinoma (phase I/II study)." J Clin Endocrinol Metab, 1994;78(1):188-96. PMID: 8288703.
- [clinical-trial] Ladenson PW, et al. "Comparison of administration of recombinant human thyrotropin with withdrawal of thyroid hormone for radioactive iodine scanning in patients with thyroid carcinoma." N Engl J Med, 1997;337(13):888-96. PMID: 9302303.
- [clinical-trial] Haugen BR, et al. "A comparison of recombinant human thyrotropin and thyroid hormone withdrawal for the detection of thyroid remnant or cancer." J Clin Endocrinol Metab, 1999;84(11):3877-85. PMID: 10566623.
- [clinical-trial] Pacini F, et al. "Radioiodine ablation of thyroid remnants after preparation with recombinant human thyrotropin in differentiated thyroid carcinoma: results of an international, randomized, controlled study." J Clin Endocrinol Metab, 2006;91(3):926-32. PMID: 16384850.
- [clinical-trial] Hänscheid H, et al. "Iodine biokinetics and dosimetry in radioiodine therapy of thyroid cancer: procedures and results of a prospective international controlled study of ablation after rhTSH or hormone withdrawal." J Nucl Med, 2006;47(4):648-54. PMID: 16595499.
- [clinical-trial] Taïeb D, et al. "Quality of life changes and clinical outcomes in thyroid cancer patients undergoing radioiodine remnant ablation (RRA) with recombinant human TSH (rhTSH): a randomized controlled study." Clin Endocrinol (Oxf), 2009;71(1):115-23. PMID: 18803678.
- [clinical-trial] Mallick U, et al. "Ablation with low-dose radioiodine and thyrotropin alfa in thyroid cancer." N Engl J Med, 2012;366(18):1674-85. PMID: 22551128.
- [review] Ma C, et al. "rhTSH-aided low-activity versus high-activity regimens of radioiodine in residual ablation for differentiated thyroid cancer: a meta-analysis." Nucl Med Commun, 2013;34(12):1150-6. PMID: 24025918.
- [review] Ma C, et al. "Recombinant human thyrotropin (rhTSH) aided radioiodine treatment for residual or metastatic differentiated thyroid cancer." Cochrane Database Syst Rev, 2010;2010(11):CD008302. PMID: 21069705.
- [pubmed] Kanamori R, et al. "Long-Term Safety and Effectiveness of Thyrotropin Alfa in Japanese Patients: A Post-Marketing Surveillance Study." Adv Ther, 2021;38(9):4949-4960. PMID: 34386895.
Sources & Citations
Studies were read from their PubMed abstracts; the label from DailyMed (Thyrogen, set b52dfa36, version 20, effective February 24, 2023), read October 28, 2026; approval record from Drugs@FDA.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.