TAC1 and carcinoid heart disease: Significantly higher median values of all 5 biomarkers were found in the patients with carcinoid heart disease compared to those without, (NT-proBNP 474 vs. 79 ng/L, 5HIAA 353 vs. 57 ng/ml, CgA 16 vs. 7 ng/ml, CgB 13 vs. 8 ng/ml and NkA 27 vs. 16 ng/L, Figure 2).