Carcinoid Syndrome

Question 1

Define carcinoid syndrome

Answer 1

Systemic release of humoral factors from carcinoid tumours

Question 2

What are the causes/risk factors for carcinoid syndrome?

Answer 2

• Carcinoid tumours are slow-growing neuroendocrine tumours mostly derived from
serotonin-producing enterochromaffin cells in the foregut, midgut or hindgut
• They produce serotonin, histamine, kallikrein and prostaglandin which are released
into the portal circulation -> metabolised by the liver
• Carcinoid syndrome is present mostly in patients with liver metastases where the
products are released into the hepatic vein -> systemic circulation

Carcinoid tumours -> carcinoid syndrome
• Liver metastases (95%)
• Bronchial tumours
• Extensive retroperitoneal metastases
• Ovarian tumours

Question 3

What are the symptoms of carcinoid syndrome?

Answer 3

• Paroxysmal flushing
• Diarrhoea
• Crampy abdominal pain
• Wheeze
• Sweating
• Palpitations

Question 4

What are the signs of carcinoid syndrome?

Answer 4

• Facial flushing
• Telangiectasia
• Wheeze
• Right sided heart murmurs
• Nodular hepatomegaly

Carcinoid crisis
• Profound flushing
• Bronchospasm
• Tachycardia
• Fluctuating BP

Question 5

What investigations are carried out for carcinoid syndrome?

Answer 5

• Urinary 5-HIAA - 24-hour urinary 5-hydroxyindoleacetic acid:
elevated
A serotonin metabolite.
• Serum Chromogranin A/B - elevated.
• FBC - usually Normal
• U&Es - may show dehydration and hypokalaemia due to diarrhoea.
• LFTs - variable; may show elevated AST/ALT in liver metastases.
• CT/ MRI - to localise the tumour.
• Radioisotope Scan - somatostatin Receptor Scintigraphy ± Somatostatin Single Photon Emission Computer Tomography (SPECT):
Radiolabelled somatostatin analogue (e.g. indium-111 octreotide) helps localise tumour.
• Endoscopy/ Bronchoscopy - helps localisation of the tumour.
• Investigations for MEN-1