Hypothyroidism (Underactive Thyroid)

Hypothyroidism means the thyroid gland is not producing enough thyroid hormone. Without enough of it, many body functions slow down. Common symptoms include fatigue, weight gain, feeling cold, constipation, dry skin, thinning hair, depression, and a slower heart rate. Symptoms often develop gradually, so many people do not notice them at first.

The National Institute of Diabetes and Digestive and Kidney Diseases says nearly 5 out of 100 Americans ages 12 and older have hypothyroidism, although most cases are mild. Women are much more likely than men to develop it, and it is more common after age 60. Causes include Hashimoto's disease, thyroid surgery, radioactive iodine treatment, radiation to the neck, and some medicines. Treatment is usually levothyroxine, a pill identical to the hormone a healthy thyroid makes, taken every day.

Because treatment depends on precise daily doses, hypothyroidism is tied to lawsuits over thyroid drugs that were weaker than labeled. When a batch is subpotent, patients can slip back into hypothyroid symptoms even though they took their pills as prescribed, and some manufacturers have recalled lots for this reason. Consumer class actions in these situations usually seek refunds for the defective product, while people with documented health effects may have individual claims.

A related condition in newborns, called congenital or neonatal hypothyroidism, is covered in its own entry. If you took a recalled thyroid medicine, keep the bottle or pharmacy records showing the lot number, and ask your doctor for your lab history. Our guide on recalls versus class actions explains what a recall means for your rights, and how to tell if you qualify for a settlement covers the next step.