From the Guidelines
A Thyrogen-stimulated full body scan is typically conducted over a 5-day period, with two intramuscular injections of Thyrogen (thyrotropin alfa) administered 24 hours apart, followed by a small dose of radioactive iodine orally, and a full body scan performed 48 hours later. This procedure is based on the most recent and highest quality study available, which prioritizes morbidity, mortality, and quality of life as the outcome 1. The instructions for the scan include:
- Receiving two intramuscular injections of Thyrogen (thyrotropin alfa), 0.9 mg each, administered 24 hours apart on days 1 and 2
- Taking a small dose of radioactive iodine (usually I-131) orally on day 3
- Undergoing a full body scan on day 5, approximately 48 hours after the radioiodine dose
- Maintaining a low-iodine diet starting 2 weeks before the scan until after the procedure is completed
- Avoiding thyroid hormone medications for 24 hours before the first Thyrogen injection until after the scan
- Staying well-hydrated and following any additional instructions from the healthcare provider regarding radiation safety precautions This procedure allows for thyroid cancer surveillance without the need for long-term thyroid hormone withdrawal, and Thyrogen stimulates any remaining thyroid tissue or cancer cells to absorb the radioactive iodine, making them visible on the scan 1. It is essential to perform this procedure under the direct supervision of a healthcare professional, as dosages and timing may be adjusted based on individual patient factors 1.
From the FDA Drug Label
2.4 Timing for Remnant Ablation and Diagnostic Scanning Following THYROGEN Administration Oral radioiodine should be given 24 hours after the second injection of THYROGEN in both remnant ablation and diagnostic scanning. The activity of 131I is carefully selected at the discretion of the nuclear medicine physician. Diagnostic scanning should be performed 48 hours after the radioiodine administration.
The instructions for a Thyrogen (thyrotropin alfa)-stimulated full body scan are:
- Administer two injections of Thyrogen 24 hours apart
- Give oral radioiodine 24 hours after the second injection of Thyrogen
- Perform diagnostic scanning 48 hours after radioiodine administration 2
From the Research
Instructions for Thyrogen-Stimulated Full Body Scan
- The Thyrogen-stimulated full body scan is used to detect residual and recurrent thyroid carcinoma in patients with differentiated thyroid cancer 3.
- The scan is typically performed after two consecutive days of Thyrogen injections, with blood tests taken on day 3 and/or day 5 to measure thyroglobulin (Tg) and anti-Tg levels 4.
- The use of Thyrogen has several advantages over thyroid hormone withdrawal, including avoiding the morbidity and discomfort associated with hypothyroidism 3, 5.
- The diagnostic radioiodine whole-body scan (DxWBS) can be avoided in patients with no clinical evidence of residual tumor and undetectable levels of Tg during hormonal suppression of TSH 3, 6.
- In patients with differentiated thyroid carcinoma at intermediate and high risk for recurrence, DxWBS in combination with stimulated Tg can be useful for detecting residual disease 6.
- The combined use of Thyrogen and iodine-123 whole-body scan can provide accurate and complete staging of disease in pediatric patients with differentiated thyroid carcinoma 7.
- Patients who undergo Thyrogen-stimulated full body scan may experience less disruption to their daily life and work compared to those who undergo thyroid hormone withdrawal 5.
Key Considerations
- Thyrogen injections are typically administered on two consecutive days, with the full body scan performed on day 3 and/or day 5 4.
- Blood tests are taken on day 3 and/or day 5 to measure Tg and anti-Tg levels, which can help detect residual disease 4, 7.
- The use of Thyrogen can help avoid the need for thyroid hormone withdrawal, which can cause hypothyroidism and disrupt daily life 3, 5.