Thyrotropin Alfa

What it is and how it works

Mechanism of Action Thyrotropin (TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroid hormone. Binding of thyrotropin alfa to TSH receptors on normal thyroid epithelial cells or on well-differentiated thyroid cancer tissue stimulates iodine uptake and organification, and synthesis and secretion of thyroglobulin (Tg), triiodothyronine (T3) and thyroxine (T4). The effect of thyroid stimulating hormone activation of thyroid cells is to increase uptake of radioiodine to allow scan detection or radioiodine killing of thyroid cells. TSH activation also leads to the release of thyroglobulin by thyroid cells.

Indications

® is a thyroid stimulating hormone indicated for: Adjunctive Diagnostic Tool for Well-Differentiated Thyroid Cancer: Use as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging in the follow-up of patients with well-differentiated thyroid cancer who have previously undergone thyroidectomy. Limitations of Use : THYROGEN-stimulated Tg levels are generally lower than, and do not correlate with Tg levels after thyroid hormone withdrawal. Even when THYROGEN-Tg testing is performed in combination with radioiodine imaging, there remains a risk of missing a diagnosis of thyroid cancer or underestimating the extent of the disease. Anti-Tg Antibodies may confound the Tg assay and render Tg levels uninterpretable. Adjunct for Thyroid Remnant Ablation in Well-Differentiated Thyroid Cancer: Use as an adjunctive treatment for radioiodine ablation of thyroid tissue remnants in patients who have undergone a near-total or total thyroidectomy for well-differentiated thyroid cancer and who do not have evidence of distant metastatic thyroid cancer.

Dosage and administration (summary)

should be used by physicians knowledgeable in the management of patients with thyroid cancer. A two-injection regimen is recommended: THYROGEN 0.9 mg is administered intramuscularly, followed by a second 0.9 mg intramuscular injection 24 hours later. Recommended Dosage THYROGEN should be used by physicians knowledgeable in the management of patients with thyroid cancer. THYROGEN is indicated as a two-injection regimen. The recommended dosage of THYROGEN is a 0.9 mg intramuscular injection to the buttock followed by a second 0.9 mg intramuscular injection to the buttock 24 hours later. THYROGEN should be administered intramuscularly only. THYROGEN should not be administered intravenously.

Contraindications

If THYROGEN is administered with radioiodine, the contraindications to radioiodine also apply to this combination regimen. Refer to the radioiodine prescribing information for a list of contraindications for radioiodine. If THYROGEN is administered with radioiodine, the contraindications to radioiodine also apply to this combination regimen.

Warnings and precautions

THYROGEN-induced hyperthyroidism: Hospitalization for administration of THYROGEN and postadministrative observation should be considered for patients at risk. Stroke: Stroke in female patients as well as other neurologic events in patients with central nervous system metastases. ( 5.2 , 5.3 ) Sudden rapid tumor enlargement: Sudden, rapid and painful enlargement in distant metastatic thyroid cancer. Risks associated with radioiodine (RAI) combination treatment: If THYROGEN is administered with RAI, the warnings and precautions for RAI also apply to this combination regimen.

Pregnancy

Pregnancy Risk Summary THYROGEN may be used in combination with radioiodine (RAI). If THYROGEN is administered with RAI, the combination regimen is contraindicated in pregnant women because fetal exposure to RAI can lead to neonatal hypothyroidism, which in some cases is severe and irreversible.

Storage and supply

Store THYROGEN refrigerated at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light.

Source: Thyrotropin Alfa (Thyrogen) — US FDA prescribing information, 2023-02-24, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.