
Determine the topic of the question-answer pair.
Question: "what produces calcitonin?";  Answer: "Calcitonin (also known as thyrocalcitonin) is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid , and in many other animals in the ultimobranchial body ."? Topic: 