• Thyroiditis is an inflammation of the thyroid gland. This can lower the amount of hormones produced.
• Hashimoto's thyroiditis is a painless disease of the immune system that is hereditary.
• Postpartum thyroiditis occurs in 5 percent to 9 percent of women after giving birth. It is usually a temporary condition.
• Iodine deficiency is a problem affecting approximately 100 million people around the world. Iodine is used by the thyroid to produce hormones. Although prevalent before the 1950s in the USA, iodine deficiency has been virtually wiped out by the use of iodized salt.
• A non-functioning thyroid gland affects one in 4,000 newborns. If the problem isn't corrected, the child will be physically and mentally retarded.

The following conditions cause hyperthyroidism:

• With Graves' disease, the entire thyroid gland might be overactive and produce too much hormone. This problem is also called diffuse toxic goiter (enlarged thyroid gland).
• Nodules might be overactive within the thyroid. A single nodule is called toxic autonomously functioning thyroid nodule, while several nodules are called a toxic multi-nodular goiter.
• Thyroiditis, a disorder that can be painful or painless, can also release hormones that were stored in the thyroid gland causing hyperthyroidism for a few weeks or months. The painless variety occurs most frequently in women after childbirth.
• Excessive iodine is found in a number of drugs such as Amiodarone, Lugol's solution (iodine), and some cough syrups, and might cause the thyroid to produce either too much or too little hormone in some individuals.