Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine

Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine. Hyperthyroidism can accelerate your body’s metabolism, causing unintentional weight loss and a rapid or irregular heartbeat.

#Symptoms
Hyperthyroidism can mimic other health problems, which can make it difficult for your doctor to diagnose. It can also cause a wide variety of signs and symptoms, including:

Unintentional weight loss, even when your appetite and food intake stay the same or increase
Rapid heartbeat (tachycardia) — commonly more than 100 beats a minute
Irregular heartbeat (arrhythmia)
Pounding of your heart (palpitations)
Increased appetite
Nervousness, anxiety and irritability
Tremor — usually a fine trembling in your hands and fingers
Sweating
Changes in menstrual patterns
Increased sensitivity to heat
Changes in bowel patterns, especially more frequent bowel movements
An enlarged thyroid gland (goiter), which may appear as a swelling at the base of your neck
Fatigue, muscle weakness