Digestive 
Blood
Cardiovascular
Dermatology
Genitourinary,
Hormones
Infections
Oncology and
Musculo-skeletal
Mental health and
Parasites
Respiratory
Senses
Various
The thyroid gland is located in the central part of the neck and produces thyroid hormones. When the thyroid gland (goitre) is enlarged, it may produce little, enough or too much thyroid hormone.
Thyroid hormones are transferred to the whole body via blood from the thyroid gland. They control how the body uses food for energy and help all the organs function well. Thyroid hormones have an effect on the metabolism, i.e., the speed at which the brain, heart, muscles, liver and other body parts function.
A goitre is an enlarged thyroid gland. The most common cause of goitre is a lack of iodine in the diet. Iodine is a substance found in food (iodized salt and seafood) that the thyroids use to make thyroid hormones.
