Thyrotropin

Summary

Thyrotropin (TSH) is a heterodimeric glycoprotein hormone produced by thyrotroph cells of the anterior pituitary. Recombinant human TSH (rhTSH, thyrotropin alfa) is used clinically as an adjunct for radioiodine ablation and thyroid cancer surveillance without requiring thyroid hormone withdrawal. It stimulates residual thyroid tissue or differentiated thyroid cancer cells to produce thyroglobulin and uptake radioiodine.

Mechanism of Action

Binds to the TSH receptor (TSHR) on thyroid follicular cells, activating adenylyl cyclase via Gs proteins, increasing intracellular cAMP, which stimulates thyroid hormone (T3/T4) synthesis and secretion, thyroid cell growth, and iodine uptake.

Routes of Administration

Goals & Uses

• Thyroglobulin surveillance in thyroid cancerOncology / DiagnosticsHigh
• Stimulation of radioiodine uptake in metastatic thyroid cancerOncologyModerate
• Radioiodine remnant ablation in differentiated thyroid cancerOncologyHigh
• Diagnostic radioiodine scintigraphyDiagnosticsHigh

Contraindications

• Large thyroid remnants with risk of swelling causing airway compromiseStructural / AnatomicalHigh
• Pediatric use (children under 16)PopulationModerate
• Hypersensitivity to thyrotropin alfa or excipientsAllergy/ImmunologyHigh

Adverse Effects

• Hypersensitivity/anaphylaxisImmunologicalRare
• HeadacheNeurologicCommonPain in the head or upper neck
• NauseaGastrointestinalCommonFeeling of sickness or urge to vomit
• FatigueGeneralCommonLow energy or tiredness
• VomitingGastrointestinalUncommonForceful expulsion of stomach contents
• Neurological deterioration / stroke-like symptomsNeurologicalRare

Drug Interactions

• LevothyroxineLow
• Radioiodine (I-131)Low

Population Constraints

• PregnancyReproductive SafetyRelative
• Renal impairmentOrgan ImpairmentRelative
• Patients with known CNS metastasesOncologyRelative
• Elderly patientsAgeRelative

Regulatory Status

• European UnionApprovedApproved: Adjunct for radioiodine remnant ablation in well-differentiated thyroid cancer, Diagnostic use with thyroglobulin testing and radioiodine scintigraphy in thyroid cancer follow-upEMA approved Thyrogen; centralized marketing authorization held by Sanofi.
• United StatesApprovedApproved: Adjunct for radioiodine remnant ablation in well-differentiated thyroid cancer, Adjunct to radioiodine scintigraphy and serum thyroglobulin testing for thyroid cancer surveillanceFDA approved Thyrogen (thyrotropin alfa) in 1998; label expanded over time. Manufactured by Genzyme/Sanofi.
• United KingdomApprovedApproved: Radioiodine remnant ablation, Thyroid cancer surveillance with thyroglobulin and radioiodine scanningApproved by MHRA; retained EU approval framework post-Brexit.

Thyrotropin alfa (Thyrogen) is FDA-approved and EMA-approved as an adjunct to radioiodine scintigraphy and serum thyroglobulin testing in patients with well-differentiated thyroid cancer. Also approved for radioiodine ablation of thyroid remnants.

Evidence & Sources

No sources recorded yet.