This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood tumors, Subject name: Pediatrics
Most common cause of of thyrotoxicosis in childhood ? 
Select and explain. 
A. Toxic nodular, B. Toxic adenoma, C. Graves disease, D. Thryotoxicosis factitia
C: Graves disease
Answer: C: Graves disease 
Explanation: Thyrotoxicosis is relatively uncommon in children.It is most commonly seen in young girls,caused by Grave&;s disease.The presence of goiter,infiltrative eye signs(lid lag,ophthalmoplegia,absence of wrinkling,chemosis,proptosis) and hypehyroidism is suggestive of Grave&;s disease. Graves disease is an autoimmune disease. The immune system normally protects the body from germs with proteins called antibodies. But with an autoimmune disease, the body makes antibodies that attack its own tissues. With Graves disease, antibodies cause the thyroid gland to make too much thyroid hormone. This is known as hypehyroidism. Excess thyroid hormone in the bloodstream causes the body&;s metabolism to be too active. This can lead to problems such as weight loss, nervousness, fast heabeat, tiredness, and other issues. Graves disease is an ongoing (chronic) condition that needs lifelong treatment or watching. Reference:Essential pediatrics-Ghai,8th edition,page no:520