THYROGEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for THYROGEN (THYROGEN).
Recombinant human thyroid-stimulating hormone (TSH) that binds to TSH receptors on thyroid follicular cells, stimulating iodine uptake, thyroglobulin synthesis, and release of thyroid hormones.
| Metabolism | Metabolized by peptide hydrolysis to amino acids. |
| Excretion | Primarily renal (thyrotropin is a glycoprotein hormone; intact hormone is minimally excreted unchanged; metabolic degradation products are eliminated renally). After IV administration, approximately 96% of the dose is recovered in urine within 24 hours as low molecular weight degradation products. Biliary/fecal excretion is negligible (<1%). |
| Half-life | 12-15 hours (terminal elimination half-life in patients with normal renal function; may be prolonged in renal impairment). Clinically, TSH levels peak by 3 hours after IM injection and return to baseline by 24-48 hours. |
| Protein binding | Approximately 25-35% bound to plasma proteins (primarily alpha-2-macroglobulin and albumin). Binding is non-saturable and reversible. |
| Volume of Distribution | 0.3-0.4 L/kg (approx. 25-30 L in a 70 kg adult; indicates distribution largely confined to extracellular fluid and plasma volume). Limited tissue penetration. |
| Bioavailability | IM: ~70-80% (relative to IV). Subcutaneous: not recommended due to inconsistent absorption. IV: 100% by definition. |
| Onset of Action | IM: Elevation of serum TSH occurs within 2-3 hours; radioiodine uptake is stimulated within 6-12 hours. IV: TSH elevation within 15 minutes; clinical effect on thyroid uptake by 6 hours. |
| Duration of Action | Single IM dose: TSH elevation lasts 24-48 hours; radioiodine uptake stimulation persists for up to 72 hours. Repeat dosing (daily for 3-5 days) produces sustained response for up to 7 days. Used for thyroid cancer follow-up: 2-3 days of TSH elevation sufficient for radioiodine imaging. |
0.9 mg intramuscular injection every 24 hours for 2 doses, or 1.2 mg orally as a single dose.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for renal impairment; GFR-based modifications not established. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); not studied in severe impairment (Child-Pugh C). |
| Pediatric use | Safety and efficacy in pediatric patients have not been established. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential age-related comorbidities and decreased renal function, though renal adjustment is not required. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for THYROGEN (THYROGEN).
| Breastfeeding | No data on excretion in human milk. M/P ratio unknown. Caution advised; consider developmental and health benefits of breastfeeding along with maternal need for Thyrogen. |
| Teratogenic Risk | Thyrogen (recombinant human TSH) is not teratogenic in animal studies. No fetal risks are expected from therapeutic use in pregnancy; however, no controlled human data exist. Use only if clearly needed. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to bovine TSH or any component of the formulation"]
| Precautions | ["Thyroid storm or exacerbation of hyperthyroidism in patients with residual thyroid tissue","Tumor lysis syndrome in patients with metastatic thyroid cancer","Neck pain, nausea, headache, and injection site reactions","May decrease the sensitivity of thyroglobulin testing if used inappropriately"] |
Loading safety data…
| Monitor thyroid function tests (TSH, free T4) and clinical signs of hyperthyroidism. No specific fetal monitoring required beyond standard obstetric care. |
| Fertility Effects | No known adverse effects on fertility. Thyrogen is used as a diagnostic or adjunctive therapeutic agent and does not impair reproductive function. |