In fact, several drugs can stimulate CT secretion, i.e., proton pump inhibitors (PPIs) and beta-blockers and, as with most tumor biomarkers, the blood concentration of CT may also increase in other pathological conditions such as chronic renal failure, autoimmune thyroiditis, hypergastrinemia, sepsis, type 1A pseudohypoparathyroidism and mastocytosis [76]. This evidence concerns the gene CALCA and pseudohypoparathyroidism type 1A.