Stimulation tests for diagnosis of medullary thyroid carcinoma.

We compared the maximal calcitonin secretion produced by pentagastrin, calcium, and glucagon for preoperative detection of medullary thyroid carcinoma in four subjects with normal or slightly increased plasma immunoreactive calcitonin (iCT) levels. In each case, pentagastrin administration produced higher peak iCT levels (5- to 36-fold increases over basal) than did calcium infusion (by 1.9- to 10.3-fold) and glucagon administration (by 3.6- to 27.4-fold). These preliminary studies suggest that pentagastrin is an effective agent for use in rapid stimulation tests designed to detectmedullary thyroid carcinoma in asymptomatic patients who have normal basal iCT concentrations.