Is lithium a suitable treatment for hyperthyroidism?

From the Guidelines

Lithium can be considered as an alternative therapy for hyperthyroidism, particularly in specific situations such as thyroid storm, pregnancy, or when standard treatments are contraindicated or ineffective. According to the most recent and relevant evidence, lithium works by inhibiting thyroid hormone release and reducing the conversion of T4 to T3 1. The standard treatment for hyperthyroidism typically involves antithyroid medications like methimazole or propylthiouracil (PTU), or nonreversible thyroid ablation therapy such as radioactive iodine or surgery 1. However, lithium can be used as an alternative when these treatments are not suitable.

Key Considerations for Lithium Use

• Lithium carbonate is typically prescribed at doses of 300-900 mg daily, divided into multiple doses, with target serum levels of 0.6-1.2 mEq/L.
• Treatment requires regular monitoring of lithium levels, thyroid function, and kidney function due to lithium's narrow therapeutic window and potential toxicity.
• Side effects can include tremor, nausea, increased urination, and long-term kidney damage.
• Lithium is particularly useful in thyroid storm (severe hyperthyroidism), during pregnancy when other options are limited, or as a short-term bridge therapy before surgery or radioactive iodine treatment.

Clinical Context and Evidence

The use of lithium in hyperthyroidism is supported by evidence from studies on thyroid storm, where lithium is listed as an alternative to saturated solution of potassium iodide or sodium iodide 1. Additionally, guidelines for managing patients with atrial fibrillation, which can be associated with hyperthyroidism, emphasize the importance of restoring a euthyroid state to manage the arrhythmia 1. However, the primary treatment for hyperthyroidism remains antithyroid medications or thyroid ablation therapy, with lithium considered for specific cases where these options are not viable 1.

Recommendation

Given the potential benefits and risks, lithium should be used under the supervision of healthcare providers experienced in managing both thyroid disorders and lithium therapy. This ensures that the medication's significant monitoring requirements and potential complications are adequately addressed, prioritizing the patient's morbidity, mortality, and quality of life outcomes.

From the FDA Drug Label

Previously existing underlying thyroid disorders do not necessarily constitute a contraindication to lithium treatment; where hypothyroidism exists, careful monitoring of thyroid function during lithium stabilization and maintenance allows for correction of changing thyroid parameters, if any

Lithium is not a suitable treatment for hyperthyroidism. The provided drug label discusses lithium treatment in the context of hypothyroidism, not hyperthyroidism, and does not provide information on its use for hyperthyroidism. 2

From the Research

Lithium as a Treatment for Hyperthyroidism

• Lithium has been studied as a potential treatment for hyperthyroidism, particularly in cases where other treatments are contraindicated or ineffective 3, 4.
• Research has shown that lithium can inhibit iodine uptake and reduce thyroid hormone production, making it a potential adjunctive therapy for hyperthyroidism 4, 5.
• A pilot study found that low-dose lithium therapy increased radioiodine retention in the thyroid gland and reduced serum FT4 levels in patients with hyperthyroidism, suggesting its potential as a treatment to enhance the efficacy of radioactive iodine therapy 3.
• A case report described the successful use of lithium in combination with oral iodine to manage hyperthyroidism in a patient with Graves' disease, highlighting its potential as a safe and effective adjunctive treatment 4.

Safety and Efficacy of Lithium for Hyperthyroidism

• The safety and efficacy of lithium for hyperthyroidism have been evaluated in several studies, with results suggesting that it can be a useful treatment option in certain cases 3, 4, 5.
• However, lithium is not routinely used as a primary treatment for hyperthyroidism due to its potential side effects and the availability of other effective treatments 5.
• The optimal dosage and duration of lithium therapy for hyperthyroidism are not well established, and further research is needed to determine its role in the management of this condition 3, 4.

Comparison with Other Treatments for Hyperthyroidism

• Other treatments for hyperthyroidism, such as antithyroid drugs, radioactive iodine ablation, and surgery, are more commonly used and have a more established role in the management of this condition 6, 5, 7.
• The choice of treatment for hyperthyroidism depends on various factors, including the underlying cause, severity of symptoms, and patient preferences 6, 7.
• Lithium may be considered as an adjunctive treatment in certain cases, such as when other treatments are contraindicated or ineffective, or as a means to reduce the dose of radioactive iodine required for therapy 3, 4.