A thyroid disease is a medical condition impairing the function of the thyroid. Different thyroid diseases include Hashimoto’s thyroiditis, hyperthyroidism and hypothyroidism. These diseases have a large range of symptoms and affect all ages.
Imbalance in production of thyroid hormones arises from dysfunction of the thyroid gland itself, the pituitary gland, which produces thyroid-stimulating hormone (TSH), or the hypothalamus, which regulates the pituitary gland via thyrotropin-releasing hormone (TRH). Concentrations of TSH increase with age, requiring age-corrected tests. Hypothyroidism affects between three and ten percent of adults, with incidence higher in women and the elderly.