KLK4 and carcinoid syndrome: Hindgut tumors from the distal colon and rectum rarely secrete 5-HT or any other vasoactive hormones and are, therefore, unassociated with hormonal syndromes even when metastatic [5]. In a patient with normal hepatic function, the 5-HT and kallikrein are metabolized by the liver and the manifestations of carcinoid syndrome do not occur unless liver metastasis occurs [1].