Calcitonin

The Calcitonin test measures the level of calcitonin, a hormone produced by the C-cells of the thyroid gland. Calcitonin plays a minor role in calcium regulation, but it is primarily used as a tumor marker for diagnosing and monitoring medullary thyroid carcinoma (MTC), a rare type of thyroid cancer.

1. What Is Calcitonin?

• Calcitonin is a hormone secreted by the parafollicular C-cells of the thyroid gland.

• It helps regulate calcium and phosphate levels in the blood by inhibiting bone resorption.

• Although it has limited importance in daily calcium balance, it serves as a key marker for certain thyroid conditions.

2. Why Is the Calcitonin Test Performed?

This test is used to:

• Detect medullary thyroid carcinoma (MTC), including early or inherited forms (MEN 2 syndrome).

• Monitor patients after thyroid cancer treatment for recurrence.

• Evaluate thyroid nodules to determine if further testing is needed.

• Screen family members of patients with hereditary MTC.

3. Calcitonin Reference Ranges

• Normal ranges vary by lab and sex:

  - Men: < 10 pg/mL

  - Women: < 5 pg/mL

• Higher values may be considered normal in newborns or during pregnancy.

4. How to Interpret Calcitonin Results

🔹 Elevated Calcitonin:

• Strongly associated with medullary thyroid carcinoma (MTC)

• May also occur in conditions such as C-cell hyperplasia, chronic renal failure, or certain lung cancers

🔹 Normal Calcitonin:

• Suggests low likelihood of MTC but may not completely rule it out, especially in early stages

5. What Can Affect Calcitonin Levels?

• Medullary thyroid carcinoma or C-cell hyperplasia

• Kidney disease

• Smoking or proton pump inhibitors (e.g., omeprazole)

• Other cancers (e.g., small cell lung cancer)

6. How Is the Test Performed?

• A blood sample is drawn, usually without the need for fasting.

• In some cases, a stimulation test using calcium or pentagastrin may be done to provoke calcitonin release.

7. When to See a Doctor

🚨 Contact your healthcare provider if you:

• Have a thyroid nodule with elevated calcitonin

• Have a family history of medullary thyroid carcinoma or MEN 2 syndrome

• Experience symptoms such as a lump in the neck, difficulty swallowing, or hoarseness

🔹 Key Takeaways

✅ Calcitonin is a thyroid hormone used as a tumor marker for medullary thyroid carcinoma (MTC).

✅ Elevated levels may indicate thyroid cancer or other medical conditions requiring further evaluation.

✅ The test is essential in diagnosing, monitoring, and screening for MTC and C-cell disorders.