From the Guidelines
The primary treatment for Iodinated Contrast (IC) induced hyperthyroidism is typically beta-blockers and supportive care, as the condition is often self-limiting. For symptomatic patients:
- Propranolol 10-40 mg orally every 6-8 hours as needed for symptom control (e.g., palpitations, tremors) 1.
- Monitor thyroid function tests every 1-2 weeks until stabilization. If severe or persistent:
- Consider short-term corticosteroids (e.g., prednisone 0.5-1 mg/kg/day) for 1-2 weeks with gradual tapering.
- In rare cases of thyroid storm, use higher doses of steroids and intensive supportive care. Importantly, do not use anti-thyroid drugs like methimazole or propylthiouracil, as they are ineffective in this condition. The hyperthyroid phase is typically followed by hypothyroidism, so be prepared to initiate thyroid hormone replacement (levothyroxine) when TSH rises and free T4 falls below normal. This approach is based on the understanding that IC-induced hyperthyroidism results from immune-mediated destruction of thyroid tissue, leading to a transient release of thyroid hormones, as seen in similar conditions such as ICI-induced hyperthyroidism 1.
Key considerations in management include:
- Grading of thyrotoxicosis severity to guide treatment decisions, with Grade 1 being asymptomatic or mild symptoms, Grade 2 being moderate symptoms, and Grade 3-4 being severe or life-threatening symptoms 1.
- The role of endocrine consultation for additional workup and possible medical thyroid suppression in cases of persistent thyrotoxicosis.
- The importance of close monitoring of thyroid function to catch the transition to hypothyroidism, the most common outcome for transient subacute thyroiditis.
Overall, the management of IC-induced hyperthyroidism prioritizes supportive care, symptom management, and monitoring for the transition to hypothyroidism, with a focus on minimizing morbidity, mortality, and impact on quality of life.
From the FDA Drug Label
In patients with Graves’ disease with hyperthyroidism or toxic multinodular goiter for whom surgery or radioactive iodine therapy is not an appropriate treatment option. To ameliorate symptoms of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy.
The treatment for hyperthyroidism, including Iodinated Contrast (IC) induced hyperthyroidism, is methimazole. Methimazole is indicated for patients with hyperthyroidism, including those with Graves' disease, for whom surgery or radioactive iodine therapy is not an appropriate treatment option. It is also used to ameliorate symptoms of hyperthyroidism in preparation for thyroidectomy or radioactive iodine therapy 2 2.
- Key points:
- Methimazole is used to treat hyperthyroidism
- It is indicated for patients with Graves' disease or toxic multinodular goiter
- Methimazole can be used to prepare patients for thyroidectomy or radioactive iodine therapy
- The dosage of methimazole should be adjusted based on thyroid function tests to avoid excessive doses 2.
From the Research
Treatment for Iodinated Contrast (IC) Induced Hyperthyroidism
The treatment for IC induced hyperthyroidism can be challenging, as drugs commonly used to treat hyperthyroidism have little effect on already formed thyroid hormone due to iodine excess 3.
- Treatment options include:
- Beta-blockers and antithyroid thionamide drugs 4
- Reinstitution of iodine to block thyroid hormone release or corticosteroids may be necessary in some cases 4
- Antithyroid drugs and perchlorate to decrease thyroid hormone synthesis and further iodine uptake into the thyroid 5
- Perchlorate can be administered in high-risk settings in combination with antithyroid drugs, if possible starting one day before the iodine exposure 5
- Discontinuation of iodine excess, antithyroid drugs, potassium perchlorate, and, if necessary, thyroidectomy or a therapeutic dose of iodide 131 6
- Corticosteroids for type II hyperthyroidism, which may occur several years after the initiation of iodine excess 6, 7
Types of Hyperthyroidism
There are two types of hyperthyroidism that may develop in excess iodine:
- Type I: reveals an undetected pretoxic thyroid disease, treated with discontinuation of iodine excess, antithyroid drugs, potassium perchlorate, and, if necessary, thyroidectomy or a therapeutic dose of iodide 131 6
- Type II: induced by excess iodine in previously normal thyroid gland or in an euthyroid goiter, may occur several years after the initiation of iodine excess, and treated with corticosteroids 6, 7