Type of publication:
Conference abstract
Author(s):
*Bevis M.
Citation:
Anaesthesia; Jul 2017; vol. 72 ; p. 30
Abstract:
VIPomas are rare neuroendocrine tumours that secrete excessive vasoactive intestinal peptide causing refractory diarrhoea, hypokalaemia and metabolic acidosis. This case describes the difficulties in diagnosing a rare cause of diarrhoea on the ITU. A 76-year-old male, with a background of type 2 diabetes, presented to hospital with a 3-day history of confusion, muscle weakness, lethargy and profuse diarrhoea. The patient had been having diarrhoea for two months but colonoscopy was unremarkable. On examination the patient was dehydrated and had a heart rate of 110 min-1, otherwise no abnormality was found. Blood tests showed metabolic acidosis (pH 7.17, base excess -15.4 mmol.L-1, bicarbonate 12.9 mmol.L-1) and severe hypokalaemia (K+ 1.3 mmol.L-1). He was admitted to ITU for aggressive fluid resuscitation and electrolyte correction. The patient had large volumes of watery diarrhoea (8 l every 24 h) which was unresponsive to loperamide and codeine. Stool cultures were negative. CT of the abdomen revealed a solitary focal liver lesion and a possible focal abnormality in the pancreatic tail. A gut hormone profile was sent for analysis. Although the diagnosis was unclear, the patient was started on octreotide which slowed the diarrhoea after a few days. Histology of the liver lesion confirmed neuroendocrine tumour, and both vasoactive intestinal peptide and pancreatic polypeptide were raised in the blood, therefore a diagnosis of pancreatic VIPoma was made. Discussion VIPomas are very rare, affecting less than 1 in 1,000,000 patients each year in the UK [1]. The cause of most VIPomas is unknown; however multiple endocrine neoplasia type 1 is a risk factor [1]. VIPomas are slow growing and are often malignant. Patients often develop symptoms slowly and may have diarrhoea for years before a diagnosis is made. The diarrhoea is large-volume, has a dilute tea appearance, and is not affected by fasting. Tests for VIPoma include serum vasoactive intestinal peptide (however this needs to be processed at a specialist centre), CT, MRI and octreoscan [1, 2]. Initial treatment focuses on fluid and electrolyte replacement as untreated severe electrolyte imbalance can lead to arrhythmias, cardiovascular collapse and death. Somatostatin analogues, such as octreotide, help control the symptoms of diarrhoea; however, the main treatment is surgical [2]. In conclusion, although VIPomas are rare they should be suspected in patients that present with profuse chronic diarrhoea with no obvious cause.