What to Do When Silent Thyroiditis Phases Into Hypothyroidism

What is the standard treatment for hypothyroidism that develops following silent thyroiditis?

— Nancy R. Wilson, FNP

Silent thyroiditis, or more precisely, silent subacute thyroiditis, generally has a hyperthyroid phase, which usually lasts several weeks, followed by a hypothyroid phase, which also lasts several weeks. The hyperthyroid phase is often mild and self-limited, and as such, treatment is usually not required. Should treatment be needed, a β-blocker is usually sufficient. Note that standard antithyroid drug treatment with propylthiouracil or methimazole is not effective, because the mechanism of the hyperthyroidism is not excessive thyroid hormone production but release of stored thyroid hormone. The hypothyroid phase of silent subacute thyroiditis is often mild as well, and no treatment is generally required if symptoms are not severe. When symptoms are more prominent, a short course of L-thyroxine therapy is in order. Keep in mind that because the hypothyroidism is usually transient, this treatment should be stopped after several weeks. Very rarely, the hypothyroidism may persist.

— Jay Silverberg, MD
   Division of Endocrinology and Metabolism
   Sunnybrook & Women’s College Health Science Center
   University of Toronto