After reading this note you will be able to construct a systematic clinical approach to a patient with suspected malabsorption, recognise the common tropical and HIV‑related aetiologies seen in Kenya, interpret the key investigations and outline safe initial and definitive management. Always verify drug choices, doses and local protocols against the Kenya MoH guideline and your hospital formulary.
Definition
Malabsorption is the impaired digestion and/or absorption of macronutrients (carbohydrates, proteins, fats), micronutrients (vitamins, minerals) and electrolytes, leading to quantitative nutrient loss despite an adequate oral intake.
Anatomy and physiology you need
| Segment | Primary function in absorption | Key transport mechanisms |
|---|---|---|
| Stomach | Mechanical breakdown, gastric lipase, acid‑dependent activation of pancreatic enzymes | Pepsin, acid‑dependent ionisation |
| Duodenum (proximal small bowel) | Major site for iron, calcium, folate, simple sugars, peptide absorption | Sodium‑dependent cotransport, active calcium transport (vitamin D‑dependent) |
| Jejunum | Principal site for carbohydrate, amino‑acid, most vitamin absorption | Carrier‑mediated, facilitated diffusion |
| Ileum | Bile‑acid, vitamin B12 (intrinsic factor complex) and bile‑salt recycling | Apical ileal bile‑acid transporter, cubilin‑mediated B12 uptake |
| Colon | Water, electrolyte, short‑chain fatty acid absorption (from bacterial fermentation) | Passive diffusion, Na⁺/H⁺ exchange |
Integrity of the mucosal brush border enzymes (lactase, sucrase‑isomaltase, peptidases) and the lymphatic lacteal network for long‑chain fatty acids are essential. Disruption at any level can produce a malabsorptive picture.
Causes and risk factors
| Category | Representative conditions in Kenya | Why they matter |
|---|---|---|
| Infectious | HIV enteropathy, intestinal TB, chronic malaria, giardiasis, cryptosporidiosis, strongyloidiasis | Direct mucosal injury, villous blunting, diarrhoea, immune suppression |
| Inflammatory/autoimmune | Celiac disease, Crohn’s disease, ulcerative colitis | Auto‑immune villous atrophy, transmural inflammation |
| Post‑surgical / anatomical | Small‑bowel resection, bariatric surgery, blind loop syndrome | Reduced absorptive surface, bacterial overgrowth |
| Pancreatic exocrine insufficiency | Chronic pancreatitis, cystic fibrosis, pancreatic TB | Lack of lipases, amylase, proteases → fat maldigestion |
| Hepatobiliary | Primary sclerosing cholangitis, cholestasis, gallstone disease | Impaired bile‑acid delivery → fat malabsorption |
| Tropical / haematologic | Sickle‑cell disease (recurrent vaso‑occlusive gut ischemia), rheumatic fever (post‑streptococcal gut involvement) | Repeated ischemic injury, immune‑mediated mucosal damage |
| Medications / toxins | Long‑term antibiotics, antitubercular therapy (rifampicin), antiretrovirals (especially protease inhibitors) | Altered flora, direct mucosal toxicity |
| Others | Protein‑losing enteropathy, Whipple disease | Rare but documented in tertiary centres |
Pathophysiology
- Mucosal injury → villous blunting → ↓ surface area → ↓ nutrient uptake
- Enzyme deficiency (e.g., lactase, pancreatic lipase) → incomplete digestion → osmotic diarrhoea, steatorrhea
- Bile‑acid depletion → impaired micelle formation → fat maldigestion → fatty stools & loss of fat‑soluble vitamins
- Transport defects (e.g., B12‑IF complex loss) → selective micronutrient deficiency → megaloblastic anaemia, neurologic signs
- Increased intestinal permeability → loss of proteins & electrolytes → hypoalbuminaemia, oedema, electrolyte disturbances
- Bacterial overgrowth → deconjugation of bile acids, competition for nutrients → exacerbates fat loss and produces gas‑related symptoms
Arrows illustrate the cascade:
Mucosal injury → ↓ absorptive area → nutrient loss → clinical malabsorption
Enzyme deficiency → undigested substrates → osmotic load → diarrhoea → further nutrient loss
End of Part 1.
Clinical features
| Aspect | Key questions to ask | Why it matters / pathophysiologic link |
|---|---|---|
| Stool pattern | Frequency, volume, consistency, presence of steatorrhea (floats, foul‑smelling, greasy), mucus or blood | Fat malabsorption → bulky, oily stools; mucosal inflammation → mucus; ulceration or infection → blood |
| Weight & growth | Unintentional weight loss, change in body habitus, difficulty gaining weight (especially in younger trainees) | Negative energy balance from loss of macronutrients; chronic disease may blunt appetite |
| Dietary intake | Recent changes, restrictive diets, food intolerances, alcohol use, high‑fat meals | Helps separate primary malabsorption from functional or dietary causes |
| Symptoms of nutrient deficiency | Fat‑soluble vitamin deficiency (night blindness, easy bruising, bone pain), iron deficiency (pallor, fatigue), B12 deficiency (paresthesias, gait disturbance) | Specific malabsorption sites (duodenum → iron/B12; ileum → B12; pancreas → fat soluble vitamins) |
| Abdominal pain / bloating | Timing (post‑prandial), character, relation to meals, radiation | Motility disturbance, bacterial overgrowth, pancreatic insufficiency |
| Systemic illness | HIV status, TB treatment, recent malaria, sickle‑cell crises, rheumatic disease, use of antibiotics or antitubercular drugs | Underlying tropical or immunologic conditions that predispose to malabsorption |
| Medication history | Long‑term antibiotics, metformin, antiepileptics, antiretrovirals, NSAIDs | Drug‑induced mucosal injury or pancreatic toxicity |
| Family history | Celiac disease, cystic fibrosis, hereditary fructose intolerance | Genetic predisposition to specific malabsorptive disorders |
Examination findings and rationale
| Finding | What it indicates | Pathophysiologic explanation |
|---|---|---|
| Cachexia / low BMI | Chronic nutrient loss | Energy deficit from macronutrient malabsorption |
| Peripheral edema / ascites | Hypoalbuminemia | Loss of protein absorption → low oncotic pressure |
| Dermatitis or hyperpigmented skin | Fat‑soluble vitamin A deficiency | Impaired absorption of retinol |
| Easy bruising, petechiae | Vitamin K deficiency | Reduced synthesis of clotting factors |
| Angular stomatitis, glossitis | Riboflavin or B‑complex deficiency | Malabsorption of water‑soluble vitamins |
| Neurological signs (paresthesias, gait ataxia) | Vitamin B12 deficiency | Ileal disease or bacterial overgrowth consuming B12 |
| Bony tenderness or fractures | Vitamin D deficiency | Fat malabsorption → osteomalacia |
| Abdominal distension, tympany | Gas from bacterial overgrowth or unabsorbed carbohydrates | Stasis of luminal contents |
| Steatorrhea on stool exam | Fat malabsorption | Pancreatic exocrine insufficiency, bile salt loss, mucosal disease |
| Digital clubbing | Chronic hypoxia or long‑standing inflammatory bowel disease | Release of growth factors from inflamed mucosa |
| Signs of chronic liver disease (spider naevi, palmar erythema) | Concomitant hepatobiliary disease affecting bile flow | Bile is essential for fat emulsification |
Differential diagnosis
| Condition | Points toward it | Key discriminators |
|---|---|---|
| Celiac disease | Diarrhoea, weight loss, iron deficiency, family history, onset after gluten exposure | Positive anti‑tTG IgA, villous atrophy on duodenal biopsy; improves on gluten‑free diet |
| Chronic pancreatitis / pancreatic exocrine insufficiency | Steatorrhea, epigastric pain, history of alcohol use, TB or HIV‑related pancreatic involvement | Low fecal elastase, imaging showing calcifications or ductal changes |
| Tropical sprue | Recent travel to high‑altitude or coastal Kenya, chronic diarrhoea, folate deficiency, HIV co‑infection | Responds to tetracycline + folic acid; duodenal biopsy shows partial villous blunting |
| Small‑bowel bacterial overgrowth (SBBO) | Abdominal bloating, flatulence, recent antibiotics, HIV, sickle‑cell disease | Positive glucose or lactulose breath test; improvement with rifaximin |
| Giardiasis | Recent water exposure, malodorous fatty stools, HIV | Stool ova & parasite positive for Giardia; responds to nitazoxanide |
| Inflammatory bowel disease (Crohn’s) | Abdominal pain, weight loss, perianal disease, extra‑intestinal manifestations | Skip lesions, granulomas on biopsy; colonoscopy findings |
| Bile acid malabsorption (ileal resection, TB ileitis) | Chronic diarrhoea, urgency, normal stool fat, history of ileal disease | Positive SeHCAT test (if available) or response to cholestyramine |
| Cystic fibrosis (adult presentation) | Recurrent respiratory infections, pancreatic insufficiency, family history | Sweat chloride test, CFTR mutation analysis |
| Medication‑induced (e.g., metformin, antiretrovirals) | Temporal relation to drug start, absence of structural disease | Discontinuation leads to symptom resolution |
Investigations
| Test | What it answers | Interpretation |
|---|---|---|
| Stool fat quantification (72‑hour collection) | Presence and degree of steatorrhea | >7 g fat/day = significant fat malabsorption |
| Fecal elastase‑1 | Pancreatic exocrine function | <the protocol dose/g = pancreatic insufficiency |
| Serum electrolytes, albumin, total protein | Nutritional status, protein loss | Low albumin → protein‑losing enteropathy |
| Complete blood count + iron studies + folate & B12 | Micronutrient deficiencies | Microcytic anemia → iron loss; macrocytosis → B12/folate deficiency |
| Serum vitamin A, D, E, K levels | Fat‑soluble vitamin status | Low levels confirm fat malabsorption |
| Anti‑tTG IgA & total IgA | Celiac disease screening | Positive → celiac; low total IgA may need IgG‑based test |
| Breath test (glucose or lactulose) | Small‑bowel bacterial overgrowth | ↑ H₂ or CH₄ within 90 min = positive |
| Upper GI endoscopy with duodenal biopsies | Mucosal architecture, celiac, tropical sprue, TB | Villous blunting → celiac/tropical sprue; granulomas → TB |
| Abdominal ultrasound / CT | Pancreatic morphology, biliary obstruction, TB lesions | Dilated pancreatic duct or calcifications = chronic pancreatitis |
| SeHCAT retention test (if available) | Bile acid malabsorption | Retention <15 % at 7 days = significant loss |
| Stool ova & parasite, Giardia antigen | Infectious causes | Positive → targeted antimicrobial therapy |
Diagnosis and severity
- Confirm malabsorption – Presence of ≥2 objective markers (e.g., steatorrhea >7 g/day, fecal elastase <the protocol dose/g, low fat‑soluble vitamins) together with clinical symptoms.
- Classify by predominant nutrient loss
- Fat malabsorption – Positive stool fat, low fat‑soluble vitamins, low fecal elastase.
- Carbohydrate/protein malabsorption – Predominant diarrhoea without fat, low serum albumin, iron/B12 deficiency.
- Determine aetiology – Use targeted serology, imaging, endoscopy, breath test, and microbiology as outlined. The most likely cause in Kenyan clinical rotations is a combination of infectious (TB, HIV‑related opportunistic infections, giardiasis) and tropical sprue.
- Severity grading (clinical)
| Severity | Clinical criteria | Management focus |
|---|---|---|
| Mild | Weight loss <5 % of body weight, stool fat <10 g/day, no electrolyte disturbance | Oral supplementation, dietary modification, treat underlying cause |
| Moderate | Weight loss 5–10 %, stool fat 10–20 g/day, mild hypoalbuminemia, mild anemia | Add medium‑chain triglyceride (MCT) oil, parenteral vitamin replacement if needed, consider pancreatic enzyme replacement |
| Severe | Weight loss >10 %, stool fat >20 g/day, albumin <30 g/L, electrolyte derangements, severe anemia or neuropathy | Initiate total parenteral nutrition (TPN) if oral intake impossible, aggressive correction of deficiencies, hospital admission, multidisciplinary team involvement |
- Document aetiology on the discharge summary and plan for definitive therapy (e.g., gluten‑free diet for celiac, tetracycline + folate for tropical sprue, pancreatic enzyme replacement for exocrine insufficiency, antitubercular therapy for ileal TB).
- Re‑assessment – Repeat key labs (albumin, vitamin levels) and stool fat after 4–6 weeks of therapy to gauge response and adjust supplementation.
End of part 2.
Management
Immediate stabilisation
- Fluid & electrolyte replacement – isotonic saline or Ringer’s lactate; add potassium or bicarbonate if labs show deficits.
- Correct severe anaemia – transfuse packed red cells if haemoglobin < 7 g/dL or symptomatic.
- Treat hypoglycaemia – give dextrose 50 % orally or intravenously if unconscious.
- Empiric broad‑spectrum antibiotics only if there is fever, leukocytosis, or suspicion of bacterial over‑growth/enteric infection (e.g., ciprofloxacin class).
Definitive treatment – directed at the underlying aetiology and the malabsorption itself.
| Underlying cause | First‑line therapy | Rationale |
|---|---|---|
| Celiac disease | Gluten‑free diet | Removes antigenic trigger; rapid symptom resolution. |
| Tropical sprue | Tetracycline class + folic acid | Antimicrobial effect; folate corrects megaloblastic anaemia. |
| HIV‑associated chronic diarrhoea | Optimise ART + metronidazole class if Cystoisospora suspected | ART restores immunity; metronidazole covers common protozoa. |
| Intestinal TB | Rifampicin‑based regimen (standard TB therapy) | Eradicates Mycobacterium; improves mucosal healing. |
| Pancreatic exocrine insufficiency | Pancrelipase (enteric‑coated) | Supplies lipase, amylase, protease; improves fat absorption. |
| Small‑bowel bacterial over‑growth (SBBO) | Rifaximin class (or metronidazole) for 2 weeks | Reduces bacterial load, alleviates bloating and steatorrhea. |
| Micronutrient deficiencies | Oral/IV replacement (iron, folic acid, vitamin B12, fat‑soluble vitamins) | Reverses anaemia, neuropathy, osteopenia. |
| Chronic pancreatitis / cystic fibrosis | High‑calorie, medium‑chain triglyceride (MCT) diet + pancreatic enzymes | MCTs are absorbed directly; enzymes aid digestion. |
Monitoring & follow‑up
- Weight & BMI weekly for the first month, then monthly.
- Stool fat quantification (72‑hour collection) after 4 weeks of therapy to gauge response.
- Serum electrolytes, albumin, complete blood count at baseline, then 2 weeks, then monthly until stable.
- Micronutrient levels (vitamin D, B12, folate) every 3 months.
- Endoscopic reassessment (duodenal biopsy) 6–12 months after gluten‑free diet if celiac disease suspected.
Contra‑indications & safety
- Avoid gluten in any patient with confirmed or suspected celiac disease.
- Tetracyclines contraindicated in pregnancy and children < 8 years.
- Rifaximin should not be used in patients with known hepatic failure without dose adjustment.
- Pancrelipase may cause fibrosing colonopathy if excessive tablets are taken; educate patients on tablet count.
Complications and prognosis
| Complication | Clinical impact | Prevention / management |
|---|---|---|
| Severe protein‑energy malnutrition | Weight loss, oedema, immune suppression | Early nutritional rehabilitation, high‑protein diet, supplements |
| Micronutrient deficiency (e.g., vitamin D, B12) | Osteomalacia, neuropathy, anaemia | Routine labs, targeted replacement |
| Osteoporosis / fractures | Reduced bone mineral density | Calcium + vitamin D, weight‑bearing exercise, DEXA screening |
| Chronic diarrhoea → electrolyte derangement | Cardiac arrhythmias, renal impairment | Ongoing electrolyte monitoring, rehydration |
| Increased infection risk (especially HIV/TB) | Opportunistic infections | Optimize ART/TB therapy, prophylactic antibiotics when indicated |
| Small‑bowel bacterial over‑growth → further malabsorption | Worsening steatorrhea, bloating | Periodic courses of rifaximin, probiotic consideration |
| Malignancy (e.g., enteropathy‑associated T‑cell lymphoma in celiac) | Poor prognosis | Long‑term gluten‑free adherence, surveillance endoscopy in refractory cases |
Prognosis is excellent when the aetiology is identified and treated promptly; chronic refractory cases carry higher morbidity.
High‑yield exam points
- Look‑alikes: differentiate celiac disease (autoimmune, anti‑tTG positive) from tropical sprue (response to antibiotics + folate).
- Common wrong first step: prescribing high‑fat diet before confirming pancreatic insufficiency; the correct step is to assess stool fat and give enzyme replacement.
- Bedside examiner question: “What feature of the abdominal exam would make you suspect pancreatic exocrine insufficiency rather than celiac disease?” (Answer: soft, non‑tender abdomen with no villous atrophy signs; presence of steatorrhea and weight loss without diarrhoea‑related urgency).
- Key lab clue: low serum albumin with normal liver enzymes points to malabsorption rather than hepatic synthetic failure.
- Important history: recent travel to endemic regions, HIV status, TB exposure – these steer you toward tropical sprue or intestinal TB.
Clinical case
Case: 28‑year‑old male, HIV‑positive (CD4 = 180 cells/µL), presents with 3 months of watery diarrhoea, weight loss of 8 kg, and occasional foul‑smelling stools. Physical exam: thin, mildly dehydrated, no abdominal tenderness. Labs: Hb 10 g/dL, serum albumin 2.8 g/dL, folate low, stool microscopy shows no ova/parasites, stool fat 12 g/72 h (normal < 7 g).
Questions
- What is the most likely aetiology?
Answer: HIV‑associated chronic diarrhoea with small‑bowel bacterial over‑growth (SBBO).
- Which immediate intervention is essential?
Answer: Fluid and electrolyte replacement plus initiation of ART optimisation; start rifaximin for SBBO.
- What long‑term dietary advice should be given?
Answer: Low‑simple‑sugar, high‑protein diet with medium‑chain triglyceride supplementation; avoid raw foods that may harbour pathogens.
Practice questions
Question 1
A 45‑year‑old woman with newly diagnosed celiac disease presents with persistent diarrhoea despite strict gluten‑free diet for 4 weeks. What is the next best step?
A. Add oral steroids
B. Check for refractory celiac disease with repeat duodenal biopsy
C. Start tetracycline class antibiotics
D. Increase dietary fibre
Answer: B. repeat duodenal biopsy to assess for refractory disease.
Explanation: Persistent symptoms after adequate diet raise suspicion for refractory celiac; steroids are reserved after confirmation.
Question 2
A 60‑year‑old man with chronic pancreatitis complains of bulky, foul‑smelling stools. Which investigation will confirm pancreatic exocrine insufficiency?
A. Serum amylase level
B. 72‑hour stool fat collection
C. Abdominal CT scan
D. Hydrogen breath test
Answer: B. 72‑hour stool fat collection.
Explanation: Quantifies steatorrhea; imaging does not assess functional enzyme output.
Question 3
A child from a malaria‑endemic area presents with chronic diarrhoea, anaemia, and low serum folate. Which treatment is most appropriate?
A. Iron tablets alone
B. Folate supplementation only
C. Tetracycline class plus folic acid
D. Antimalarial therapy only
Answer: C. tetracycline class plus folic acid.
Explanation: Tropical sprue responds to antibiotics and folate; iron alone would not correct folate‑deficiency anaemia.
Question 4
A patient with HIV (CD4 = 90) develops watery diarrhoea and abdominal bloating. Stool PCR is negative for Cryptosporidium. Which drug class should be avoided as first‑line therapy?
A. Metronidazole class
B. Rifaximin class
C. Fluoroquinolone class
D. Macrolide class
Answer: C. fluoroquinolone class.
Explanation: Fluoroquinolones have limited activity against typical HIV‑related protozoa and carry higher risk of tendon toxicity in immunocompromised patients.
Question 5
A 35‑year‑old man with intestinal TB completes 2 months of intensive phase therapy but still has steatorrhea. What explains the persistence?
A. Drug‑induced pancreatitis
B. Co‑existent pancreatic insufficiency
C. Resistant Mycobacterium strain
D. Ongoing HIV infection
Answer: B. co‑existent pancreatic insufficiency.
Explanation: TB can involve the pancreas; persistent malabsorption after TB control suggests pancreatic enzyme deficiency.
Drafted with AI assistance from standard references and reviewed for structure. Check details against your lecture notes and the Kenya MoH guideline.