Which serum marker is typically elevated in medullary thyroid carcinoma?

Which serum marker is typically elevated in medullary thyroid carcinoma?

• A. Calcitonin
• B. TSH
• C. Thyroglobulin
• D. PTH

Answer: (A)

Calcitonin is elevated because medullary thyroid carcinoma arises from the thyroid’s parafollicular C cells, which normally secrete calcitonin. When these cells become malignant, they continue to produce calcitonin, so its levels in the blood rise and the marker can be used to help diagnose the cancer and monitor treatment or recurrence. TSH is a pituitary hormone and isn’t a cancer marker for thyroid tumors. Thyroglobulin comes from thyroid follicular cells and is a marker mainly for differentiated thyroid cancers like papillary or follicular types, not medullary. PTH is produced by the parathyroids and is unrelated to medullary thyroid carcinoma.

Calcitonin is elevated because medullary thyroid carcinoma arises from the thyroid’s parafollicular C cells, which normally secrete calcitonin. When these cells become malignant, they continue to produce calcitonin, so its levels in the blood rise and the marker can be used to help diagnose the cancer and monitor treatment or recurrence. TSH is a pituitary hormone and isn’t a cancer marker for thyroid tumors. Thyroglobulin comes from thyroid follicular cells and is a marker mainly for differentiated thyroid cancers like papillary or follicular types, not medullary. PTH is produced by the parathyroids and is unrelated to medullary thyroid carcinoma.