What are the key clinical features of carcinoid syndrome that I should look for in my patients?

Key clinical features of carcinoid syndrome to look for in patients include:

• Flushing: Sudden episodes of red, warm skin, typically on the face and upper chest, often triggered by stress, alcohol, or certain foods.
• Diarrhoea: Frequent, watery stools that may be persistent and severe, sometimes accompanied by abdominal cramping.
• Wheezing and bronchospasm: Respiratory symptoms resembling asthma due to bronchoconstriction.
• Right-sided cardiac valvular lesions: Signs of carcinoid heart disease such as fatigue, peripheral oedema, or heart murmurs, reflecting fibrotic damage to heart valves.
• Abdominal pain: May be present due to tumour burden or mesenteric fibrosis.
• Other symptoms: Include pellagra-like skin changes from niacin deficiency, and less commonly, flushing may be accompanied by hypotension or tachycardia.

These features arise from the secretion of vasoactive substances like serotonin and tachykinins by neuroendocrine tumours, primarily when liver metastases bypass hepatic metabolism, allowing systemic effects ¹ (Vinik et al., 1989; Mota et al., 2016; Subash et al., 2022).