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Questions and Answers
Which of the following features is most consistently associated with osmotic diarrhea due to malabsorption?
Fat malabsorption can lead to symptoms such as ascites and edema.
True
What is an essential aspect of the evaluation steps for malabsorption?
Confirm the diagnosis clinically
In cases of vitamin B₁₂ deficiency due to intestinal malabsorption, it is primarily linked to __________ pathology.
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Match the following clinical features with their corresponding deficiencies or conditions:
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Which clinical feature is considered typical for celiac disease?
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Dermatitis herpetiformis is the most important association with celiac disease.
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List one probable association with celiac disease.
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Celiac disease can lead to __________ due to malabsorption of vitamin D and calcium.
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Match the clinical features or associations with their descriptions:
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What is the first step in Phase 1 of the Schilling Test?
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In Phase II of the Schilling Test, antibiotics are administered.
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What indicates that further tests should be conducted during the Schilling Test?
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In Phase 1 of the Schilling Test, after administering 1000 µg of unlabeled vitamin B12, the next step is to administer ___ of oral radioactive vitamin B12.
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Match the following steps in the Schilling Test phases with their corresponding actions:
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What is the gold standard investigation for fat malabsorption?
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Fever is a symptom commonly seen in malabsorption.
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What type of monosaccharide is D-xylose?
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In the process of fat malabsorption, fatty acid interacts with Ca2+ to produce free ________ in the gut.
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Match the following tests with their associated type of malabsorption:
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What is the primary reason for false positives in renal failure related to malabsorption testing?
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The C-14 Triolein breath test is still considered a valid test for fat malabsorption.
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What does a significant increase in breath hydrogen (H₂) above 20 ppm indicate in the Lactose H₂ breath test?
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The __________ H₂ breath test is used to diagnose Small Intestinal Bacterial Overgrowth (SIBO).
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Match the following diagnostic tests with their corresponding conditions:
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What is a key defect in abetalipoproteinemia?
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Steatorrhea is one of the clinical presentations of abetalipoproteinemia.
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What is the characteristic finding on a peripheral blood smear for abetalipoproteinemia?
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In abetalipoproteinemia, there is a deficiency in the absorption of __________ vitamins.
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Match the symptoms of abetalipoproteinemia with their corresponding conditions:
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What bacteria are responsible for fermenting undigested carbohydrates in the colon?
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Diaper dermatitis in children with protein malabsorption typically presents with a neutral pH.
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What is a key laboratory test used to diagnose lactose malabsorption?
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In cases of fat malabsorption, one potential disorder affecting post mucosal absorption is __________.
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Match the following conditions with their clinical presentations:
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Which component of gluten is primarily responsible for triggering celiac disease?
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A gluten-free diet can lead to normalization of conditions in clinically affected individuals within six months.
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What is the role of tissue transglutaminase in the pathophysiology of celiac disease?
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The most toxic component of gluten is __________.
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Match the following outcomes with their respective statistics regarding a gluten-free diet and celiac disease progression:
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What is the most important clinical presentation associated with primary intestinal lymphangiectasia?
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Chylomicrons transport fats from the intestines to the lymphatic system and then to the blood.
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Name one condition that can lead to secondary intestinal lymphangiectasia.
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In intestinal lymphangiectasia, the presence of elevated fecal α1-antitrypsin indicates ________.
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Match the following features with their related investigations or management:
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What is the most common cause of malabsorption related to small intestinal mucosal dysfunction?
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Atypical celiac disease presents primarily with malabsorption symptoms.
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Name the two HLA types associated with the predisposition to celiac disease.
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The classic form of celiac disease typically presents with ____% of cases showing symptoms of malabsorption.
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Match the types of celiac disease with their characteristics:
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Study Notes
Clinical Features & Tests For Malabsorption
- Osmotic diarrhea is a common symptom of malabsorption, caused by an excess of undigested material in the small intestine.
- Fat malabsorption can lead to abdominal bloating, foul-smelling stools, ascites, and edema.
- Vitamin B12 deficiency can cause anemia, peripheral neuropathy, ataxia, glossitis, cheliosis, and stomatitis.
- Vitamin A deficiency can result in night blindness, xerophthalmia, and follicular hyperkeratosis.
- Tetany, fractures, and bone pain are musculoskeletal manifestations of malabsorption.
- Hyperpigmentation, perifollicular hemorrhage, curly hair, spiral hair, bruisability, ecchymoses, acrodermatitis, and follicular hyperkeratosis are cutaneous manifestations of malabsorption.
- Growth retardation is a possible outcome of malabsorption.
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Schilling test is a two-phase test used to diagnose vitamin B12 malabsorption
- Phase 1 involves administering unlabeled vitamin B12 intramuscularly followed by oral radioactive vitamin B12. Urine samples are collected to measure the excreted radioactive vitamin to evaluate absorption
- Phase 2 involves repeating the procedure with the administration of intrinsic factor, antibiotics or pancreatic enzymes, to identify the specific cause for malabsorption.
- Classical/Typical Celiac is characterized by osmotic diarrhea, abdominal distension, foul-smelling stools, weight loss, and symptoms of IBS.
- Atypical Celiac patients may present with short stature, failure to thrive, fractures, osteopenia, ataxia, peripheral neuropathy, and iron deficiency anemia.
- Secondary hyperparathyroidism due to low vitamin D and Calcium absorption is associated with celiac disease.
- Hyposplenism is a potential complication of celiac disease, indicated by the presence of Howell-Jolly bodies.
- Dermatitis herpetiformis is the most important associated feature of celiac disease, characterized by papulovesicular lesions on extensor surfaces.
- Other conditions associated with celiac disease include Down syndrome, Type I diabetes mellitus, IgA nephropathy, IgA deficiency, hypersensitivity pneumonitis, lymphocytic colitis, and cerebral calcifications with epilepsy.
- Probable associations with celiac disease include cryptogenic transaminitis/cirrhosis, idiopathic short stature, refractory iron deficiency anemia, and cerebellar ataxia.
- Kidney stones can form as a consequence of fat malabsorption due to the increased production of free oxalate in the gut.
- Fat malabsorption can be assessed using qualitative tests like Sudan III and quantitative tests like fecal fat excretion.
- Fecal fat excretion ≥ 7 g/day is considered the gold standard for diagnosing fat malabsorption.
- D-xylose test is the best and most specific test for carbohydrate malabsorption. It assesses the integrity of the small intestinal mucosa.
- A positive D-xylose test suggests normal small intestinal absorption while a low D-xylose level indicates malabsorption. False positive results can occur due to renal failure, rapid intestinal transit, small intestinal bacterial overgrowth (SIBO), and ascites.
Abetalipoproteinemia
- Abetalipoproteinemia is an autosomal recessive disorder characterized by a defect in microsomal triglyceride transport protein (MTTP).
- This defect impairs the formation of apoB48, leading to defective esterification and the absence of chylomicron formation.
- Clinical presentation includes hypolipidemia, steatorrhea, ataxia, and retinitis pigmentosa, forming a classic triad.
- Peripheral smear shows acanthocytes, while post-prandial biopsy demonstrates vacuolation in enterocytes.
- Abetalipoproteinemia is 100% diagnostic on biopsy.
- Fat malabsorption further contributes to deficiencies in vitamins A, D, E, and K, leading to the neurologic symptoms of ataxia. Low levels of these vitamins also impact the liver and intestine, affecting vitamin secretion.
Celiac Disease Pathophysiology
- Individuals with HLA DQ2 or HLA DQ8 are susceptible to celiac disease. This means they are more likely to develop the condition when exposed to gluten.
- Gluten, found in wheat, barley, rye, and oats, triggers the disease.
- The prolamine fraction of gluten, particularly gliadin, is the most toxic component.
- Gliadin reacts with glutamine in the small intestine, forming a dimer.
- This dimer is deamidated by tissue transglutaminase, a process leading to the formation of a deamidated glutamine dipeptide.
- This deamidated dipeptide activates T cells, triggering an immune response that damages the small intestine.
- This leads to the characteristic damage and malabsorption seen in celiac disease.
Physiology of GIT Absorption & Selective Malabsorption
- Undigested carbohydrates, not absorbed in the colon, are fermented by colonic bacteria like Bacteroides fragilis, Bifido bacteria, and Lactobacillus.
- This fermentation process produces gas, which causes abdominal distension, bloating, and cramps about 90 minutes after meals.
- In young children, acidic stool pH may lead to diaper dermatitis.
- Lactose hydrogen breath test is a common test for lactose intolerance, measuring the amount of hydrogen produced in the breath after consuming lactose.
- Fat malabsorption, a symptom of various disorders including abetalipoproteinemia and intestinal lymphangiectasia, occurs when fats are not properly absorbed in the digestive system.
- Protein malabsorption can be associated with Hartnup's disease, which has a similar clinical presentation to pellagra, and cystinuria, characterized by the excretion of cystine, ornithine, lysine, and arginine.
Intestinal Lymphangiectasia
- Intestinal lymphangiectasia is characterized by dilated lymphatic channels within the intestinal wall.
- This dilation increases lymphatic pressure, leading to leakage of lymph fluid into the intestinal lumen.
- The most important manifestation is protein-losing enteropathy (PLE), which results in hypoalbuminemia and hypoglobulinemia, causing edema and ascites.
- Diarrhea is another common symptom.
- Primary intestinal lymphangiectasia results from abnormally dilated lymphatic channels, while secondary intestinal lymphangiectasia arises from lymph node obstruction as seen in conditions like lymphoma and Crohn's disease.
- Fecal α1-antitrypsin levels are elevated in intestinal lymphangiectasia and serve as a specific marker for diagnosing the condition.
- CT scans reveal thickened small intestinal walls, while video capsule endoscopy provides further diagnostic information.
- Management of intestinal lymphangiectasia often includes a medium-chain triglyceride diet.
Global Malabsorption
- Global malabsorption involves defective absorption of carbohydrates, fats, and proteins, indicating a general dysfunction of the small intestinal mucosa.
- Celiac disease, Whipple's disease, and tropical sprue are common causes of global malabsorption.
- Celiac disease, also known as celiac sprue, gluten-sensitive enteropathy, or non-tropical sprue, is characterized by an immune-mediated reaction to gluten, leading to damage of the small intestinal mucosa.
- Celiac disease primarily affects the proximal small intestine, including the duodenum and ileum.
- The iceberg phenomenon describes the underdiagnosis of celiac disease, with only 50% of cases presenting with classical symptoms.
- HLA DQ2/DQ8 are the most significant genetic predispositions for the development of celiac disease.
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Celiac disease is classified into classical, atypical, silent, and latent forms.
- Classical celiac disease presents with symptoms related to malabsorption.
- Atypical celiac disease is characterized by symptoms unrelated to malabsorption.
- Silent celiac disease is asymptomatic but serologically positive.
- Latent celiac disease is asymptomatic, has negative antibodies but exhibits HLA susceptibility.
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Description
Explore the various clinical features and diagnostic tests for malabsorption. This quiz covers key symptoms such as osmotic diarrhea, fat malabsorption, vitamin deficiencies, and related tests like the Schilling test. Test your knowledge and understanding of this important medical condition!
