Hyperthyroidism symptoms may include sudden weight loss, rapid heartbeat, tremors, fatigue, sleep difficulties and an enlarged thyroid gland, which is also called a goiter, according to the Mayo Clinic. Hyperthyroidism symptoms can mimic other health conditions, and some medications can mask symptoms, making it difficult to diagnose.
Graves' ophthalmopathy is a less common hyperthyroidism symptom that affects the eyes. It can cause the eyeballs to bulge out due to swelling of muscles and tissues behind the eyes. In addition to protruding eyeballs, symptoms may include redness, tearing, discomfort, sensitivity and changes in vision acuity. Patients should describe to the doctor the symptoms, including onset, severity and frequency.