Final answer:
Graves' disease is considered primary hyperthyroidism because it directly involves the thyroid gland, which is stimulated by abnormal antibodies to overproduce thyroid hormones, leading to symptoms such as heat intolerance, rapid heartbeat, weight loss, goiter, and exophthalmia.
Step-by-step explanation:
Graves' disease is an autoimmune disorder that is classified as primary hyperthyroidism. In this condition, the thyroid gland is directly affected. Abnormal antibodies, specifically thyroid-stimulating immunoglobulin (TSI), also known as TSH-receptor antibody, stimulate the thyroid gland to overproduce thyroid hormones, overriding the body's normal regulatory mechanisms. This leads to symptoms such as heat intolerance, rapid and irregular heartbeat, weight loss, and goiter (an enlarged thyroid), as well as exophthalmia, known as Graves' ophthalmopathy, characterized by bulging eyes.
Unlike secondary hyperthyroidism, which is caused by excessive TSH secretion from the pituitary gland, Graves' disease is due to the thyroid gland itself producing too much hormone as a result of an immune system disorder. Therefore, the feedback loop regulating thyroid hormone production is disrupted, causing an excessive secretion of the hormones.
The treatment of Graves' disease often includes medications to reestablish a balanced secretion of thyroid hormones and manage the symptoms of hyperthyroidism.