💡 Malabsorption = impaired absorption of nutrients (macro- and micronutrients) in the small intestine. ⚠️ Can lead to diarrhoea, weight loss, nutritional deficiencies, and systemic complications. 🔑 Management requires: accurate diagnosis, targeted therapy, dietary modification, and correction of deficiencies.

📊 Malabsorption: High-Yield Cause–Feature–Management Table

Cause	Key Clinical Features	Investigations (NICE-aligned)	First-Line Management / Therapy
Coeliac Disease 🌾	💩 Diarrhoea, 🍞 bloating, ⚖️ weight loss, 😴 fatigue, 🩹 dermatitis herpetiformis	🧪 Anti-tTG IgA, total IgA, 🩻 duodenal biopsy (villous atrophy)	🥗 Lifelong gluten-free diet, 💊 iron/folate/calcium/vit D supplementation, 👩‍⚕️ dietitian input
Lactose Intolerance 🥛	💨 Bloating, 💩 diarrhoea, 💭 flatulence after dairy ingestion	🧪 Hydrogen breath test, 🚫 elimination diet trial	🥛 Lactose-free diet or lactase enzyme supplements
Chronic Pancreatitis / Pancreatic Insufficiency 🍽️	💩 Steatorrhea, ⚖️ weight loss, 🥚 fat-soluble vitamin deficiency, 🌡️ epigastric pain	🧪 Fecal elastase, 🩻 CT/MRCP, pancreatic function tests	💊 PERT (pancreatic enzyme replacement therapy), 🥚 fat-soluble vitamins, 💊 analgesia, 🚫 alcohol cessation
SIBO (Small Intestinal Bacterial Overgrowth) 🦠	💨 Bloating, 💩 diarrhoea, 🥩 nutrient deficiencies (B12, iron), ⚖️ mild malnutrition	🧪 Glucose/lactulose hydrogen breath test, 🧫 jejunal aspirate culture	💊 Antibiotics (rifaximin), 🥗 dietary modification, 🔄 treat underlying motility disorder
Crohn’s Disease 🩺	💩 Chronic diarrhoea, 🌡️ abdominal pain, ⚖️ weight loss, 🩸 anaemia, 🔗 perianal disease	🩻 Colonoscopy + biopsy, 🩻 MR enterography, 🧪 faecal calprotectin, 💉 bloods (FBC, CRP)	💊 Induction: steroids; 💉 Maintenance: immunomodulators, biologics; 🔪 Surgery for strictures/fistulae
Tropical Sprue 🌴	💩 Chronic diarrhoea, 😴 fatigue, 🥩 folate/B12 deficiency, ⚖️ weight loss	🩻 Small bowel biopsy, 💉 serum folate/B12	💊 Antibiotics (tetracycline), 💉 folate and vitamin B12 supplementation
Cystic Fibrosis (GI manifestation) 🫁	🤧 Chronic cough, 💩 steatorrhea, ⚖️ poor growth, 🥗 malnutrition	🧪 Sweat chloride test, 🧬 CFTR genotyping, 💩 fecal elastase	💊 PERT, 🥚 fat-soluble vitamin supplementation, 🥗 nutritional support, 🤸‍♂️ physiotherapy
Whipple’s Disease ⚠️	💩 Diarrhoea, ⚖️ weight loss, 🤕 arthralgia, 🧠 neurological symptoms, 💩 steatorrhea	🩻 Duodenal biopsy (PAS-positive macrophages), 🧬 PCR for Tropheryma whipplei	💉 Prolonged IV → oral antibiotics (ceftriaxone → TMP-SMX), 🥗 nutritional support

🩺 Clinical Features

💩 Chronic diarrhoea, often steatorrhea (fat malabsorption)
💨 Abdominal bloating, cramping, excessive flatus
⚖️ Weight loss despite adequate caloric intake
🦴 Calcium & Vitamin D deficiency → osteoporosis, osteomalacia, tetany
🩸 Iron deficiency → microcytic anaemia; Folate/B12 deficiency → macrocytic anaemia, glossitis, neuropathy
🧪 Protein malabsorption → hypoalbuminemia, oedema

🔎 Investigations

💉 Bloods: FBC (micro/macrocytic anaemia), U&E, LFTs, albumin, ferritin, vitamin B12, folate, fat-soluble vitamins (A, D, E, K), PT/INR
🩺 Serology: Anti-tTG IgA for coeliac, ASCA for Crohn’s
💨 Breath Tests: Lactose intolerance, SIBO (glucose/lactulose)
💩 Stool Analysis: Qualitative (Sudan stain), quantitative 72-h fat collection, elastase (pancreatic function), pH/reducing substances
📷 Imaging:
- Upper GI endoscopy + biopsy → coeliac, Whipple, tropical sprue
- MR enterography / small bowel follow-through → structural lesions, Crohn’s strictures
- CT abdomen/pancreas → chronic pancreatitis, masses

⚕️ Management Principles (NICE-aligned)

🥗 Dietary Modification: Tailored to cause:
- Gluten-free diet for coeliac
- Lactose-free for lactose intolerance
- Low-fat diet for fat malabsorption (chronic pancreatitis)
💊 Specific Therapies:
- Coeliac: lifelong gluten-free diet + supplementation
- Crohn’s: steroids, immunomodulators, biologics; surgery if strictures/fistulae
- Pancreatic insufficiency: PERT + fat-soluble vitamins
- SIBO: antibiotics (rifaximin), prokinetics, dietary modification
- Lactose intolerance: enzyme replacement/lactose avoidance
- Whipple’s: prolonged IV → oral antibiotics, nutritional support
💉 Supplementation: Iron, B12, folate, calcium, vitamin D, fat-soluble vitamins; route oral or parenteral depending on severity
⚖️ Caloric Support: Elemental or polymeric enteral feeds, or parenteral nutrition if severe malnutrition or short bowel
🧪 Monitoring: Weight, nutritional labs, symptom diary, bone density in chronic malabsorption
🩺 Multidisciplinary: Dietitian input, gastroenterology, possibly endocrinology or surgery

💡 Teaching Pearls

Malabsorption → always consider macro- (protein, fat, carbs) & micronutrient (iron, folate, B12, fat-soluble vitamins) deficiencies
Steatorrhea points to fat malabsorption → pancreatic vs small bowel origin
Iron deficiency anaemia with diarrhoea → coeliac until proven otherwise
Weight loss, arthralgia, neurological features → think Whipple’s disease
Breath tests are non-invasive first-line for lactose intolerance and SIBO
Endoscopy with biopsy is definitive for mucosal causes (coeliac, tropical sprue, Whipple)
Early nutritional support prevents complications (osteoporosis, neuropathy, anaemia)

📚 References (NICE-compliant)

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Malabsorption - small intestine ✅