Calcitonin screening and pentagastrin testing: predictive value for the diagnosis of medullary carcinoma in nodular thyroid disease

Serum calcitonin (hCT) measurement may be useful for detecting medullary thyroid carcinoma (MTC), but the routine use of hCT after pentagastrin stimulation to screen patients with nodular thyroid disease remains controversial.

A total of 1007 patients (567 females and 440 males) with nodular thyroid disease and a mean age of 55+/-14 (mean+/-S.D.) years were included in the study. All patients did not have impaired renal function, bacterial infection, alcohol and drug abuse, pseudohypoparathyroidism, or proton-pump inhibitor therapy. Individuals referred with known elevation of hCT, Graves' disease, or autoimmune thyroid disease were not considered or included in this investigation.

Serum hCT levels were determined under basal conditions, and when basal values were >or=10 and <100 pg/ml, testing was repeated after pentagastrin stimulation. Patients with basal or stimulated levels >100 pg/ml were referred for surgery.

hCT levels >10 pg/ml were increased in 17 patients (1.7%). One patient had a basal hCT level of 4400 pg/ml with a histological confirmation of a MTC. In this patient, pentagastrin test was not performed. Sixteen patients with basal hCT between 10 and 100 pg/ml underwent pentagastrin-stimulated hCT measurement. Of 16 patients, 4 had stimulated hCT>100 pg/ml. Of 17 patients with hCT>10 pg/ml, 2 had MTC, and of 17 patients, 3 had C-cell hyperplasia. In total, two patients (0.20%) had a histologically verified MTC.

Basal hCT measurement together with pentagastrin-stimulated hCT measurement in cases of basal hCT>10 pg/ml detects MTC in 0.20% of patients with nodular thyroid disease. Whether this high incidence of MTC has major implications or not has to be discussed, but it should be considered as a useful and recommended tool for early detection of MTC and to save patients' life.