AKT · Gastroenterology/Small bowel & malabsorptionlow yield

Malabsorption

Impaired digestion/absorption of nutrients (mucosal, luminal/pancreatic, or structural causes)

Overview

Impaired absorption of nutrients, producing steatorrhoea (pale, bulky, offensive, hard-to-flush stools), weight loss and specific deficiencies. Causes group into mucosal (coeliac, Crohn, Whipple), luminal/digestive (chronic pancreatitis, bile-salt deficiency, bacterial overgrowth) and structural/post-surgical (short bowel, resection). The task is to find the cause and replace what's missing.

Recognise

Steatorrhoea, weight loss despite adequate intake, bloating, flatulence
Deficiency signs: iron/B12/folate (anaemia), fat-soluble vitamins (A/D/E/K — bruising, bone disease, night blindness), calcium
Cause-specific clues: coeliac (gluten), chronic pancreatitis (alcohol, calcification), Crohn (terminal ileum), bacterial overgrowth (bloating, prior surgery)

Red flags

Significant weight loss / vitamin K deficiency coagulopathy
Underlying malignancy (pancreatic) or new coeliac complication

Differentials & how to tell them apart

Coeliac diseasepositive tTG, villous atrophy

Chronic pancreatitislow faecal elastase, pancreatic calcification, alcohol history

Small intestinal bacterial overgrowthabnormal hydrogen breath test; post-surgical/dysmotility

Bile salt malabsorptionwatery diarrhoea, SeHCAT test, responds to colestyramine

Investigations

FBC/ferritin, B12/folate, calcium/vitamin D, INR (vitamin K), albumin; coeliac serology; faecal elastase (pancreatic insufficiency); hydrogen breath test (bacterial overgrowth/lactose); imaging/endoscopy for the cause.

Management

Identify and treat the cause + replace the specific deficiencies

1Document the deficiency pattern and screen for common causes (coeliac serology, faecal elastase, breath tests, imaging). Replace deficiencies and treat the underlying cause.Gate: Define WHICH cause (mucosal vs pancreatic vs overgrowth vs structural) — the treatment differs entirely (gluten-free diet vs enzyme replacement vs antibiotics vs surgery)
2Cause-specific management; nutritional support; monitor deficiency correction.

Treat the cause + replace deficiencies — gluten-free diet, pancreatic enzyme replacement, antibiotics for overgrowth, etc.

Key points

Steatorrhoea + weight loss + deficiency pattern = malabsorption → find the cause (coeliac, pancreatic, overgrowth, structural). Faecal elastase splits pancreatic from mucosal causes.

Monitor & prognosis

Nutritional markers; cause-specific.

Depends on cause.

Source: BSG; StatPearls