From the Guidelines
No, levothyroxine does not need to be stopped for a Thyrogen-stimulated whole body scan and radioactive iodine treatment. Thyrogen (recombinant human TSH) is specifically designed to allow patients to continue their thyroid hormone replacement therapy while undergoing these procedures. The traditional approach required patients to stop levothyroxine for 4-6 weeks to achieve a hypothyroid state necessary for effective scanning and treatment, causing significant symptoms like fatigue, depression, and cognitive impairment. Thyrogen provides the necessary TSH stimulation to make thyroid tissue and thyroid cancer cells take up radioactive iodine without requiring the patient to become hypothyroid.
Key Points to Consider
- Patients should continue taking their levothyroxine as prescribed throughout the entire process, as supported by studies such as 1 and 1.
- Patients should follow specific dietary restrictions (low-iodine diet) for 1-2 weeks before the procedure as directed by their physician.
- Patients should inform their doctor about all medications they're taking, as some may interfere with radioiodine uptake.
- The use of rhTSH for preparation of radioiodine ablation has been approved by the European Medicine Agency (EMEA) and the FDA, as mentioned in 1 and 1.
- A recent multicenter and prospective study has demonstrated that preparation with rhTSH is highly effective and safe, with a rate of successful ablation similar to that obtained with LT4 withdrawal, as noted in 1.
From the Research
Levothyroxine and Thyrogen Stimulated Whole Body Scan
- Levothyroxine does not necessarily need to be stopped for a thyrogen stimulated whole body scan and radioactive iodine treatment, as recombinant human thyroid-stimulating hormone (rhTSH) can be used as an alternative to thyroid hormone withdrawal 2, 3, 4.
- rhTSH has been shown to be safe and effective in stimulating TSH levels, allowing for diagnostic iodine-131 imaging and serum thyroglobulin measurement without the need for thyroid hormone withdrawal 4, 5, 6.
Benefits of Using rhTSH
- Using rhTSH can help preserve quality of life in patients undergoing radioactive iodine ablation, as it avoids the need for thyroid hormone withdrawal and the resulting hypothyroidism 2, 4, 6.
- rhTSH has been shown to be well-tolerated, with mild and transient side effects such as nausea and headache 4, 6.
Clinical Applications of rhTSH
- rhTSH can be used to prepare patients for whole body iodide scans and serum Tg measurements, particularly in those who are unable to secrete pituitary TSH upon thyroid hormone withdrawal 3.
- rhTSH has been approved for diagnostic use in patients with thyroid cancer, and its use is pending regulatory approval in the European Union 4.