carcinoid syndrome, the systemic effects of serotonin-secreting carcinoid tumors, which include flushing, diarrhea, cramps, skin lesions resembling pellagra, labored breathing, palpitations, and valvular heart disease, especially of the tricuspid and pulmonary valve. Treatment includes surgical excision of the tumor, if feasible. Chemotherapy and radiation treatment are occasionally used. Also called argentaffinoma syndrome. See also carcinoid.
