Labs and Lytes 002
Author: Ronan O’ Donovan
Reviewer: Chris Nickson
A 30 year-old accountant with a 6 week history of severe back pain is to have a lumbar fixation for a vertebral lesion thought to be secondary to a large hilar lung tumour. On handover it is mentioned that the tumour might be carcinoid. His CT chest shows that a large mediastinal mass is enveloping the left main bronchus, with narrowing of the lumen.
Q1. What exactly is a carcinoid tumour?
Carcinoid tumours are neuroendocrine tumours typically arising from the GI tract or lungs
- Incidence quoted between 0.2 – 10 per 100,000 (USA)
- 75-80% of patients with carcinoid syndrome have small bowel tumours
- 5 year survival 80% but survival rate decreases to 20% with distal metastases
- 25% of carcinoid tumours develop carcinoid syndrome
Carcinoid tumours synthesise and release many vasoactive mediators, such as serotonin, histamine, kallikreins and prostaglandins
- The liver usually inactivates these mediators, thus GI carcinoid tumours only develop carcinoid syndrome with distal metastases
- Serotonin can cause diarrhoea, abdominal cramps, and even right heart valvulopathy (fibrous thickening of valves, especially tricuspid)
- Histamine and kallikreins can cause flushing and telangiectasia
- It is unclear which mediator causes bronchoconstriction
Q2. What investigations are useful for diagnosing carcinoid tumours?
Diagnosis of carcinoid tumours is through biochemical, imaging and histology in patients with the appropriate history. The key biochemical abnormalities are:
- Elevated urine 5 H1AA level
- Elevated urine serotonin
- Elevated serum chromogranin A
Q3. If the primary tumour is carcinoid how does this affect perioperative management of this patient?
The specific issue with regard to carcinoid is that — in the context of carcinoid storm or ‘crisis’, which can be prompted by anaesthesia, — they release several vasoactive mediators, chiefly serotonin, but also prostaglandins, kallikreins, and histamine.
These mediators can cause variable effects on blood pressure leading to hypertension or even hypotension.
- It is further relevant because the typical anaesthetic/ critical care practitioner’s reflex response to hypotension is start an infusion of vasopressor (i.e. catecholamines), which can cause further release of these mediators from the carcinoid tumour.
- Therefore, the response of a hypotensive patient in carcinoid storm to an infusion of noradrenaline may be a further drop in blood pressure!
- The solution is the perioperative addition of octreotide in liaison with Endocrinology colleagues. Octreotide is a somatostatin analogue which will inhibit release of the mediators.
- Multiple sources state that starting octreotide the day before a planned operation is optimal, and to continue for up to 48 hours postop.
- Also of note from a perioperative point of view is that carcinoid syndrome is associated with right heart lesions i.e. fibrous thickening and valvulopathy of the tricuspid valve. Echocardiography is recommended as part of the perioperative workup.
- Finally, resection of liver lesions represent the highest risk for the development of carcinoid crisis, as the liver is the main buffer of the body to eliminate the mediators released.
Carcinoid tumours require multidisciplinary team workup perioperatively with input from specialties such as Endocrinology, Anaesthesia and Cardiology as required.
- Mancuso K, Kaye AD, Boudreaux JP, Fox CJ, Lang P, Kalarickal PL, Gomez S, Primeaux PJ. Carcinoid syndrome and perioperative anesthetic considerations. J Clin Anesth. 2011 Jun;23(4):329-41. doi: 10.1016/j.jclinane.2010.12.009. Review. PubMed PMID: 21663822.
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