CALCA and medullary thyroid gland carcinoma: Basal serum calcitonin screening for MTC in thyroid nodule patients is somewhat controversial, as few patients have definitively high values (>100 ng/L), and diagnostic confusion is created among the greater number with marginally abnormal values of 10–100 ng/L.1,11 For example, in a type 2 diabetes population with high cardiovascular risk, 10.8% had serum calcitonin values >10 ng/L, and 2.6% had values >20 ng/L.12 A better diagnostic test would be both highly sensitive and highly specific.