Thyroid nodules are abnormal growths that form lumps on the thyroid gland in your neck. Nodules may be filled with solid or fluid. The vast majority of thyroid nodules are not cancerous, do not cause any health problems, and do not require treatment. In fact, autopsies show that nearly half of all adults develop thyroid nodules; most of these remain asymptomatic throughout life. Thyroid nodules run in families and are more likely to occur if you've been exposed to radiation or have another thyroid condition.Sometimes, a nodule may produce too much thyroid hormone. This can cause an imbalance in how much thyroid hormone the healthy gland makes, which in turn may cause noticeable symptoms.What symptoms might indicate the presence of thyroid nodules?A lump on your thyroid or swelling in your neck, if the nodule is unusually bigA rapidly growing lump in your neckDifficulty swallowingDifficulty breathingThroat pain that may travel up to the ear or jawFeeling like your throat is fullDifficulty speaking or hoarseness (rare)Enlarged lymph nodes or other glands in the neckSymptoms of hyperthyroidism (too much hormone): feeling nervous or restless, excessive sweating, a fast or irregular heartbeat, clammy skin, or sudden, unexplained weight lossSymptoms of hypothyroidism (too little hormone): feeling tired or depressed, constipation, facial swelling, dry skin, hair loss, not being able to tolerate cold, unintentional weight gain, or memory problemsWhen should you see a doctor?If you notice unusual swelling in your neck that persists for over two weeks, you should consult a physician. It's even more urgent if you're having trouble with breathing or swallowing.A hoarse voice that isn't caused by an infection and that lingers for over a month should also be evaluated by a physician.And visiting your doctor is advised if you develop any symptoms that suggest hyperthyroidism: sudden weight loss, trouble sleeping, a pounding heart, nervousness or irritability, or muscle weakness.