Final answer:
Grave's disease is commonly diagnosed using an antibody test because it is an autoimmune disorder that causes the thyroid gland to secrete excessive thyroid hormones.
Step-by-step explanation:
An antibody test is commonly used to diagnose autoimmune conditions affecting the endocrine system, such as Grave's disease. Grave's disease is characterized by hypersecretion of thyroid hormones due to the immune system producing abnormal antibodies that stimulate the thyroid gland to produce excess hormones. This is in contrast to conditions like Multiple Endocrine Neoplasia, Pheochromocytoma, and Cushing's Syndrome, which typically do not involve antibody-related mechanisms for their diagnosis.