Hyperthyroidism is too much thyroid hormone. It develops when the thyroid gland becomes overactive.
The thyroid gland is a butterfly-shaped gland in the front of the neck. It produces hormones called T3 and T4. They control the body's metabolism.
The Thyroid Gland
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Hyperthyroidism may be caused by:
- Graves' disease—problem with the immune system
- Toxic uninodular goiter—a single area/nodule in the thyroid gland is overactive
- Toxic multinodular goiter—multiple nodules in the thyroid gland which overproduce thyroid hormone
- Thyroiditis—inflammation of the thyroid that may later lead to hypothyroidism
- Taking too much thyroid hormone—very rarely from meat sources contaminated by animal thyroid glands
Last reviewedNovember 2012by Kim Carmichael, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.