<prompt> Answer this question truthfullyWhat is exogenous hyperthyroidism, and what are its distinguishing symptoms and diagnostic features?  <response>: <reason> What is exogenous hyperthyroidism, and what are its distinguishing symptoms and diagnostic features? Exogenous hyperthyroidism, also known as factitious hyperthyroidism, is a condition characterized by symptoms of hyperthyroidism but without a goiter. In addition, diagnostic scintigraphy shows low RAI uptake. 