Hyperthyroidism (Overactive Thyroid)

Hyperthyroidism happens when the thyroid, a small gland in the front of the neck, produces too much thyroid hormone. Because thyroid hormone controls how the body uses energy, too much of it speeds things up. Symptoms can include weight loss despite a bigger appetite, a fast or irregular heartbeat, nervousness, trouble sleeping, heat intolerance, shaky hands, and more frequent bowel movements.

The National Institute of Diabetes and Digestive and Kidney Diseases estimates that about 1 in 100 Americans ages 12 and older have hyperthyroidism. It is more common in women and in people over 60. Graves' disease, an autoimmune disorder, is the most common cause. Other causes include overactive thyroid nodules, thyroid inflammation (thyroiditis), too much iodine, and taking too much thyroid hormone medicine. Left untreated, it can lead to an irregular heartbeat, blood clots, stroke, heart failure, and bone thinning.

That last cause, too much thyroid hormone medicine, is where hyperthyroidism most often meets the courts. Thyroid pills are dosed in tiny amounts, so a batch that is stronger than labeled can push patients into an overactive state. Consumer lawsuits have also targeted "thyroid support" supplements that allegedly contained real thyroid hormone without saying so on the label. Claims generally require lab results showing abnormal hormone levels and records tying the change to a specific product or lot.

See our page on supplement mislabeling lawsuits, and the guide to recalls versus class actions for what a recall does and does not mean for your rights.