Screening Leading to Diagnosis of C-Cell Hyperplasia

Because virtually all medullary thyroid cancers (MTCs) are associated with elevated circulating levels of serum calcitonin (CT), routine CT measurement has been proposed as a tool for early MTC diagnosis. The usefulness of universal screening with CT in thyroid nodular disease patients is, however, controversial. Basal CT determination, in fact, displays a high false-positive rate, resulting in low positive predictive value (PPV). Provocative tests (i.e., pentagastrin or calcium gluconate administration) are often necessary to improve the specificity of the screening procedure. Nonetheless, surgical pathology indicates C-cell hyperplasia (CCH) in a substantial proportion of thyroid nodular disease patients who display positive results at CT testing (basal and/or stimulated). A basal CT >100 pg/ml is the most reliable cutoff for MTC. Below this cutoff, the threshold for discriminating CCH from MTC is not well defined.