GastroenterologyTier 2Disease (DEADMAN)

GI manifestations of systemic and chronic disease, such as amyloidosis, cystic fibrosis, diabetes, and neuroendocrine tumours

Description

Several systemic and chronic diseases not primarily gastrointestinal in origin produce characteristic GI manifestations - amyloidosis, cystic fibrosis, diabetes mellitus, and neuroendocrine tumours each affect the gut via distinct mechanisms

GI involvement is common enough in each of these conditions that gastroenterology input is frequently required as part of their multidisciplinary management, not as an unusual complication

Amyloidosis - amyloid protein deposition in the gut wall/autonomic nerves disrupts motility (causing pseudo-obstruction) and the mucosal barrier (causing malabsorption and fragile, bleeding-prone vasculature); hepatic and splenic infiltration also occur
Cystic fibrosis - thick, viscous secretions obstruct the pancreatic ducts, causing progressive exocrine insufficiency; a CF-specific meconium ileus equivalent (distal intestinal obstruction syndrome) can occur in older children/adults
Diabetes mellitus - autonomic neuropathy causes gastroparesis (delayed gastric emptying) and diabetic diarrhoea/constipation; diabetes is also a major driver of MASLD/NAFLD
Neuroendocrine tumours - covered in more depth under the hormone-secreting tumours note (carcinoid syndrome, gastrinoma/Zollinger-Ellison syndrome, VIPoma, glucagonoma)

Gastroparesis (diabetes) - confirmed by gastric emptying scintigraphy once mechanical obstruction has been excluded on endoscopy
CF pancreatic insufficiency - faecal elastase-1 (see markers of pancreatic function and malabsorption)
Amyloidosis - tissue biopsy (rectal, fat pad, or the affected GI segment) with Congo red staining, alongside typing (AL vs ATTR) to guide systemic management

Management targets the underlying systemic disease alongside symptom-directed GI treatment: prokinetics and dietary modification for gastroparesis, pancreatic enzyme replacement for CF exocrine insufficiency, and disease-specific systemic therapy for amyloidosis (chemotherapy/targeted therapy depending on amyloid type)
Nutritional support is frequently needed across all these conditions given the combination of malabsorption/reduced intake and increased metabolic demand

Autonomic neuropathy (diabetes, amyloidosis), pancreatic exocrine insufficiency, MASLD/NAFLD, carcinoid syndrome and other neuroendocrine tumour syndromes

GI manifestations in these systemic conditions are frequently under-recognised as being disease-related, and can be misattributed to an unrelated primary GI diagnosis unless the systemic condition is specifically considered in the differential

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