Elevated calcitonin levels are often associated with which type of tumor?

Elevated levels of calcitonin are most commonly associated with medullary carcinoma of the thyroid. This type of cancer arises from the parafollicular C cells of the thyroid gland, which are responsible for producing calcitonin. Calcitonin plays a role in regulating calcium homeostasis by lowering blood calcium levels, primarily by inhibiting bone resorption and promoting calcium excretion in the kidneys.

In medullary carcinoma, the tumor is characterized by the abnormal proliferation of these C cells, leading to excessive production of calcitonin. Because this elevation in calcitonin can occur significantly, it is often used as a tumor marker to help in the diagnosis and monitoring of medullary thyroid carcinoma.

In contrast, the other types of thyroid tumors, such as adenomas, follicular carcinoma, and thyroid lymphoma, are not typically associated with elevated calcitonin levels. Adenomas and follicular carcinoma primarily originate from the follicular cells of the thyroid, which produce thyroxine but not calcitonin. Thyroid lymphoma is a malignancy of the lymphoid tissue in the thyroid and does not involve C cells or calcitonin production. Therefore, the distinct relationship between increased calcitonin and medullary carcinoma of the thyroid makes