Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy for hyperthyroidism, goiter or cancer, or radioactive iodine therapy for hyperthyroidism.

The FDA has approved the use of the oral multikinase inhibitor sorafenib (Nexavar – Bayer) for treatment of locally recurrent or metastatic, progressive, differentiated thyroid cancer (papillary or follicular) refractory to radioactive iodine treatment. Sorafenib was approved earlier for treatment of advanced renal cell and unresectable hepatocellular cancer.

Teprotumumab-trbw (Tepezza - Horizon), an insulin-like growth factor-1 receptor (IGF-1R) inhibitor, has been approved by the FDA for IV treatment of thyroid eye disease. It is the first drug to be approved in the US for this indication.

The FDA recently approved vandetanib [van det´ a nib] (Caprelsa – AstraZeneca) for oral treatment of symptomatic or progressive medullary thyroid cancer (MTC) in patients with unresectable locally advanced or metastatic disease. Vandetanib is the first drug approved in the US for medullary thyroid cancer.

The FDA has approved the oral multikinase inhibitor lenvatinib (Lenvima – Eisai) for treatment of locally recurrent or metastatic, progressive, differentiated thyroid cancer (papillary or follicular) refractory to radioactive iodine treatment.

Even though it is unlikely that people living in the US will be at risk of significant radiation exposure from the nuclear accident in Japan, some readers have suggested a review of the use of potassium iodide (KI) in such circumstances. Potassium iodide taken orally before or at the time of exposure can limit or prevent uptake of radioactive iodine by the thyroid gland.

Primary hypothyroidism is usually the result of Hashimoto's (autoimmune) thyroiditis, thyroidectomy, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. Levothyroxine (LT4; synthetic thyroxine; Synthroid, and others) is the drug of choice.1

The oral kinase inhibitors selpercatinib (Retevmo – Lilly) and pralsetinib (Gavreto – Blueprint Medicines/Genentech) have been approved by the FDA for treatment of advanced or metastatic RET-mutant or RET fusion-positive cancers. They are the first drugs to be approved specifically for certain RET-driven cancers. Both drugs were granted accelerated approval based on overall response rates and the duration of response.

The FDA has determined that 3 generic formulations of levothyroxine are therapeutically equivalent to brand-name formulations. Some brand-name manufacturers have objected, and endocrine organizations have expressed their concern.
See levothyroxine addendum

Resmetirom (Rezdiffra – Madrigal), a thyroid hormone receptor-beta agonist, has received accelerated approval from the FDA for treatment of noncirrhotic nonalcoholic steatohepatitis (NASH) with moderate to advanced fibrosis in adults. NASH has recently been renamed metabolic dysfunction-associated steatohepatitis (MASH). Resmetirom is the first drug to be approved in the US for this indication.