What is thyroid hormone?

Hormone produced by the thyroid gland, thyroid hormone is essential for just about every metabolic process in the human body and a severe deficiency of thyroid hormone is fatal. Thyroid hormone declines steadily with age. Low, or sub-optimal, thyroid hormone levels results in weight gain, fatigue, cold intolerance, hair loss, thin and dry skin, and brittle nails. Restoration of thyroid hormone to optimal levels results in increased energy and metabolism and a reverse of the above symptoms.