Comparison of serum calcitonin and procalcitonin in detecting medullary thyroid carcinoma among patients with thyroid nodules.

BACKGROUND

To prospectively evaluate the role of procalcitonin (PCT) in detecting or excluding medullary thyroid carcinoma (MTC) among patients with thyroid nodules and increased calcitonin (CT) levels.

METHODS

Fourteen of 1236 patients referred for thyroid nodules had increased serum CT >10 pg/mL. A stimulation test with pentagastrin was done and both CT and PCT were measured after stimulation. All patients underwent thyroid ultrasound, fine-needle cytology and, if indicated, surgery with histological and immunohistochemical examination of the surgical specimens.

RESULTS

After follow-up, two MTCs were found. These two patients had basal CT >100 pg/mL and detectable (>0.1 ng/mL) PCT, with 100% sensitivity. Pentagastrin stimulated CT achieved values above 100 pg/mL in two MTCs and in other two cases with no MTC outcome (50% PPV and 83% NPV). On the contrary, all patients with no MTC had both basal and stimulated undetectable PCT (100% PPV and 100% NPV).

CONCLUSIONS

The addition of basal PCT measurement in patients with thyroid nodule(s) and increased CT may significantly improve accuracy of CT measurement without needing a PG stimulation test.