carcinoid syndrome
A paraneoplastic syndrome caused by excessive serotonin and other vasoactive substances released by neuroendocrine tumors.
Full Definition
Carcinoid syndrome is a constellation of symptoms resulting from the systemic release of bioactive substances, primarily serotonin, from neuroendocrine tumors. Classic manifestations include episodic flushing, diarrhea, bronchospasm, and cardiac valvular disease. The syndrome typically occurs when tumor-derived substances bypass hepatic metabolism, either through liver metastases or primary tumors with direct venous drainage to systemic circulation. Diagnosis is confirmed through elevated 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA) levels. Long-term complications may include carcinoid heart disease affecting the tricuspid and pulmonary valves.
Usage
Usage note: Distinguish from carcinoid crisis, which is an acute life-threatening exacerbation.
In Context
- "The constellation of flushing, diarrhea, and elevated 5-HIAA confirmed carcinoid syndrome." — Clinical assessment
- "Echocardiography revealed tricuspid regurgitation consistent with carcinoid syndrome." — Cardiology consultation