In patients with medullary thyroid carcinoma, calcitonin levels are often elevated. However, in a significant percentage of patients, calcitonin levels are normal or show only a borderline increase. When stimulated by an infusion of pentagastrin, calcium or both, patients with medullary thyroid carcinoma will show a marked increase in serum calcitonin levels. The combined stimulation test (pentagastrin plus calcium) is considered more reliable than either agent alone. The test can be used to screen family members of patients with the familial form of medullary thyroid carcinoma.


Patient Preparation: Pentagastrin (0.5 µg/kg) is given by an IV push over 5 seconds. Then a calcium infusion (2 mg/kg) is given IV over 1 minute.


Specimen Collection: Serum is collected as baseline, 1 minute, 2 minutes, 5 minutes, 10 minutes and 30 minutes after infusion.


Side Effects: Rapid infusion reduces the severity of side effects, which are often brief. These include headache, weakness, vomiting, diarrhea, flushing, chest discomfort, lightheadedness and nausea.




Normal: Normal serum calcitonin levels in adults are < 150 pg/mL.

• Following the infusions, patients will show a peak calcitonin level of <= 350 pg/mL in males and <= 94 pg/mL in women.

• The maximum level will be less than 3 times the baseline level. Levels peak at around 2 minutes and are dropping at 5 minutes.


Patients with Medullary Thyroid Carcinoma:

• Patients with normal or borderline increases in calcitonin will show a marked increased in calcitonin levels following stimulation, typically 3-20 (or more) times baseline levels.


Other conditions with increased levels of calcitonin:

(1) other tumors, such as breast or lung

(2) pregnancy

(3) pernicious anemia

(4) subacute thyroiditis

(5) renal failure


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