The thyroid is a gland which makes hormones and can be the cause of hyperthyroidism and hypothyroidism.
Hyperthyroidism occurs when your thyroid gland produces too much of the hormone thyroxine. This can accelerate your body’s metabolism, which causes unintentional weight loss, sweating, tremor, fatigue and irregular heartbeat among other symptoms.
Hypothyroidism is a condition in which your thyroid gland do not produce enough of certain hormones. This can cause health problems, such as obesity, infertility or heart disease if it is not treated. Some symptoms may include fatigue, hoarseness, weight gain, elevated blood cholesterol level or pain in your joints.