The causes of sudden enlargement of the thyroid gland are usually the following: 1. It is common in adolescent females, due to increased metabolism, the growth and development of the thyroid gland in the body leads to insufficient function and compensatory enlargement, which will gradually return to normal with the passage of puberty, so this condition is not serious. 2. The more serious one is subacute thyroiditis, which is a sudden enlargement of the thyroid gland. The most important thing is that you should be able to get a good idea of what you are doing. The other is thyroid crisis, which can be life-threatening, and is also based on an enlarged thyroid gland, accompanied by pain, weight loss, panic, sweating, irritability, nausea, and individual patients with protruding eyes. This kind of needs high attention, patients with thyroid crisis will have significant abnormalities and changes in blood pressure and heart rate, often causing and organ failure, so do not panic with this kind of problem, go to a specialized hospital to find a specialist for diagnosis, and then choose a reasonable disposal method.