PANCE - Malabsorption Syndromes

Here are key facts for PANCE from the Malabsorption Syndromes tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

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1. Malabsorption is the failure to assimilate one or more nutrient types due to defects in digestion, absorption, or transport. 2. Causes include deficient digestive agents (pancreatic enzymes), abnormal GI epithelium, impaired transport, short bowel, and inadequate gastric mixing. 3. Clinical presentation includes diarrhea, steatorrhea, weight loss, weakness, anemia, and vitamin/mineral deficiencies. 4. Diagnostic approach involves patient history, blood tests for specific nutrient deficiencies, fecal fat tests, Sudan III staining, endoscopy with biopsy, breath tests, and small bowel imaging. 1. Occurs when >90% of pancreatic enzyme function is lost, leading to malabsorption of fats and fat-soluble vitamins (A, D, E, K, and B12). 2. Primary causes: pancreatitis (often alcohol-induced in adults), cystic fibrosis (most common in children), and obstructive pancreatic tumors. 3. Clinical features: loose, bulky, oily, pale feces that float due to oil content; left epigastric pain radiating to back in pancreatitis. 4. Diagnosis: reduced duodenal pH and decreased fecal elastase-1 (FE-1). 1. Results from deficient lactase enzyme activity with prevalence >65% worldwide (varies by population: ~30% Europe, ~50% US, ~70% Asia, nearly 100% Africa). 2. Classified as congenital (rare autosomal recessive), primary (adult-type, common), or secondary (transient due to intestinal damage). 3. Pathophysiology: undigested lactose causes osmotic diarrhea and undergoes bacterial fermentation producing gas, bloating, and pain. 4. Diagnosis: hydrogen breath test (>20 ppm increase indicates deficiency), blood glucose tests, DNA tests, stool acidity tests. 1. Autoimmune inflammatory disorder of small bowel triggered by gliadin (gluten protein in wheat, barley, rye), affecting 1% of US adults. 2. Screening uses serological tests (tTG-IgA, tTG-IgG, deamidated gliadin peptide antibodies, EMA-IgA). 3. Definitive diagnosis requires endoscopy with small bowel biopsy showing characteristic changes with gluten exposure and improvement with gluten removal. 4. Genetic markers include HLA-DQ2 and HLA-DQ8 haplotypes (useful for ruling out celiac disease). 1. Rare disorder occurring in tropical regions (parts of India, Pakistan, Caribbean) with uncertain etiology (likely infectious/environmental). 2. Characterized by malabsorption of folic acid and vitamin B12, leading to megaloblastic anemia. 3. Histopathology shows villous atrophy, increased crypt depth, epithelial cell enlargement, and lymphocytic/inflammatory cell infiltration. 4. Distinguished from celiac disease through serologic testing despite similar histopathology. 1. Rare bacterial infection caused by Tropheryma whipplei, predominantly affecting older males of European descent with immune defects. 2. Clinical presentation progresses from arthralgias to neurologic symptoms (dementia), endocarditis, and later GI effects (diarrhea, abdominal pain, weight loss). 3. Diagnosis: PAS-positive staining of small bowel biopsy showing foamy macrophages in lamina propria and villous atrophy. 4. PCR testing for T. whipplei DNA in CSF is crucial due to potential neurologic complications.

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1. EPI: Treatment includes lifestyle modifications (alcohol cessation), vitamin supplements, and exogenous pancreatic enzyme administration. 2. Lactose Intolerance: Managed by reducing consumption of lactose-rich foods based on individual tolerance thresholds. 3. Celiac Disease: Strict gluten-free diet is the only effective treatment. 4. Tropical Sprue: Treated with folic acid and vitamin B12 supplementation plus antibiotics (tetracycline, ampicillin). 5. Whipple Disease: Requires antibiotics (ceftriaxone/penicillin followed by trimethoprim/sulfamethoxazole); fatal if untreated and relapses are common. 1. EPI primarily affects fat digestion because carbohydrate and protein digestion are maintained by enzymes from salivary glands, stomach, and small intestine. 2. Primary vs. secondary lactase deficiency: intestinal villi appear normal in primary but damaged in secondary cases. 3. Lactose intolerance differs from milk allergy, which is an immune-mediated reaction to cow's milk proteins. 4. Celiac disease has characteristic endoscopic findings including "scalloping" of duodenal folds and increased vascularity, reflecting villous atrophy and edema. 5. HLA-DQ2 and HLA-DQ8 testing for celiac disease is most useful for excluding the diagnosis when negative. 1. Celiac disease is associated with dermatitis herpetiformis (~10% of patients), reduced bone density, and increased malignancy risk. 2. Chronic pancreatitis can lead to loss of both endocrine and exocrine functions, resulting in diabetes mellitus alongside malabsorption. 3. Malnutrition can cause specific deficiency syndromes including night blindness (vitamin A), peripheral neuropathy (vitamins B1, B6, B12), and edema (protein). 4. Whipple disease can cause disabling neurologic complications if untreated. 5. Secondary lactase deficiency can result from intestinal damage caused by infections or food allergies.

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Below is information not explicitly contained within the tutorial but important for PANCE. 1. Differential diagnosis: Distinguishing between various causes of chronic diarrhea and weight loss. 2. Laboratory interpretation: Pattern recognition in nutrient deficiency panels suggesting specific malabsorptive disorders. 3. Cost-effective diagnostic algorithms: Stepwise approach to evaluation based on presenting symptoms. 4. Red flags requiring urgent intervention: Signs and symptoms needing immediate attention. 5. When to refer: Appropriate timing for gastroenterology consultation. 1. Medication absorption issues: Implications for drug effectiveness in patients with malabsorption. 2. Drug-nutrient interactions: Impact on both medication efficacy and nutrient absorption. 3. Antibiotic selection principles: Evidence-based choices for infectious causes of malabsorption. 4. Enzyme replacement therapy: Dosing strategies and monitoring parameters. 5. Managing medication side effects: Addressing adverse reactions in compromised patients. 1. Pediatric assessment: Growth chart monitoring and developmental considerations. 2. Pregnancy management: Balancing maternal nutritional needs with fetal development. 3. Geriatric presentation: Atypical manifestations and comorbidity considerations. 4. Post-surgical patients: Approach to iatrogenic malabsorption following bariatric or intestinal surgery. 5. Athletes with malabsorption: Nutritional strategies to support performance while managing symptoms.