This page discusses the thyroid gland's role in hormone production, including T4, T3, and calcitonin, which regulate metabolism and calcium levels. It highlights the effects of hypothyroidism and hype...This page discusses the thyroid gland's role in hormone production, including T4, T3, and calcitonin, which regulate metabolism and calcium levels. It highlights the effects of hypothyroidism and hyperthyroidism, including associated disorders like cretinism, myxedema, and Graves' disease. Furthermore, it covers the parathyroid glands and their secretion of PTH, which increases blood calcium.