3 - Diarrhea Flashcards
What is diarrhea defined as?
Loose, watery defecation occurring at least three or more times in a day.
What is the primary difference between acute and chronic diarrhea?
Acute diarrhea has a sudden onset and lasts for a short duration, while chronic diarrhea lasts for weeks to months to years.
List the four biochemical mechanisms of diarrhea.
- Secretory
- Osmotic
- Inflammatory
- Disordered transit time
What is secretory diarrhea characterized by?
Persistent diarrhea despite cessation of oral intake.
What causes osmotic diarrhea?
Osmotically active particles in the small intestine pulling water into the gut lumen.
What are some examples of conditions that lead to osmotic diarrhea?
- Lactose intolerance
- Celiac disease
- Pancreatic maldigestion
- Osmotic laxatives (sorbitol)
What are the cardinal manifestations of inflammatory diarrhea?
- Fever
- Abdominal pain
- Diarrhea containing blood and mucus
What characterizes dysmotility diarrhea?
Altered motility (intestinal transit time) that is either too rapid or too slow.
What common condition can lead to small intestinal bacterial overgrowth (SIBO)?
Long-standing type 1 diabetes complicated by damage to the autonomic nervous system.
What is steatorrhea?
Diarrhea containing an excess of fatty material.
What does the term ‘malabsorption’ refer to?
The gut’s inability to assimilate adequate calories (protein, carbohydrate, fat, minerals, or vitamins necessary to maintain homeostasis).
What is the significance of differentiating pancreatic maldigestion from intestinal mucosal disease?
It leads to the correct diagnosis and guides treatment more expeditiously.
What is the clinical presentation of chronic pancreatitis in children typically characterized by?
Steatorrhea and weight loss.
What does a fecal fat test using Sudan staining indicate?
The presence of fat malabsorption.
What is the principal monosaccharide in our diet?
Glucose.
Name some disaccharides found in the human diet.
- Sucrose
- Lactose
- Trehalose
What role do ATP-dependent sodium glucose transport proteins (SGLT1) play in nutrient absorption?
They facilitate the diffusion of glucose and galactose from the gut lumen into the enterocytes.
Fill in the blank: Diarrhea is a major cause of ______ in resource-poor countries.
mortality
True or False: Diarrhea is always the cardinal manifestation of malabsorption.
False
What might be misdiagnosed as irritable bowel syndrome?
Celiac disease.
What is the role of pancreatic amylase in carbohydrate digestion?
It continues the digestion of carbohydrates to maltose, maltotriose, and isomaltose.
What is the term for the inactive precursor of a digestive enzyme?
Zymogen.
What are alpha-limit dextrins?
Short chain polymers of glucose with branching after incomplete digestion by alpha amylase.
What is the significance of a tissue transglutaminase (tTG) IgA test?
It helps investigate the possibility of celiac disease.
What laboratory findings support the diagnosis of malabsorption?
- Anemia
- Low total protein
- Low albumin
What enzymes hydrolyze lactose and sucrose?
Lactase hydrolyzes lactose to glucose and galactose, and sucrase hydrolyzes sucrose to glucose and fructose.
What are the three simple sugars absorbed in the intestinal epithelium?
- Glucose
- Fructose
- Galactose
What is the role of SGLT1 in carbohydrate absorption?
SGLT1 facilitates diffusion of glucose and galactose from the gut lumen into the enterocytes.
Which transporter is responsible for transporting fructose into enterocytes?
GLUT5
What is the principal transporter for all three sugars moving them from enterocytes into circulation?
GLUT2
Where does protein digestion primarily occur?
- Stomach
- Small intestine
What activates pepsinogen into pepsin?
Hydrochloric acid secreted from parietal cells in the gastric mucosa.
What initiates the cascade of pancreatic zymogen activation in the small intestine?
Enteropeptidase cleaves trypsinogen to active trypsin.
What are the end products of protein digestion ready for absorption?
- Free amino acids
- Dipeptides
- Tripeptides
Where does the absorption of amino acids mainly occur?
Duodenum and jejunum
What enzymes generate free amino acids in the intestinal lumen?
Brush border dipeptidases
What role do lingual and gastric lipases play in lipid digestion in newborns?
They hydrolyze triglycerides to diglycerides and fatty acids.
What is the role of bile salts in lipid digestion?
Emulsification of intestinal contents.
What is the function of colipase in lipid digestion?
It binds to the water-lipid interface of emulsion droplets to activate pancreatic lipase.
What forms when monoglycerides and fatty acids remain associated with bile salts?
Mixed micelle
What type of fatty acids can diffuse directly into the enterohepatic portal circulation?
Short and medium chain fatty acids
How are long chain fatty acids processed after absorption?
They are combined with monoglycerides to re-form triglycerides and packaged into chylomicrons.
Where are most vitamins and minerals absorbed in the gut?
Jejunum and upper ileum
What is the primary mutation associated with cystic fibrosis?
Deletion of phenylalanine at position 508 (ΔF508).
What systems are primarily affected by cystic fibrosis?
- Respiratory tract
- Gastrointestinal system
- Pancreas
- Reproductive organs
What does CFTR primarily mediate?
Cl− secretion in exocrine epithelium.
What is the significance of immunoreactive trypsinogen (IRT) in cystic fibrosis?
It is used for newborn screening of CF.
What are pancreatic digestive enzymes classified as?
Zymogens
What is the consequence of decreased Cl− and HCO3− secretion in cystic fibrosis?
Hyperacidity leading to precipitation of digestive enzymes.
What is pancreatic enzyme replacement therapy (PERT) used for?
To manage pancreatic insufficiency in cystic fibrosis patients.
True or False: Only long chain fatty acids are absorbed through the intestinal mucosa.
False
Where are proteins digested and absorbed in the body?
Proteins are digested into tripeptides, dipeptides, or amino acids and absorbed in the duodenum or proximal jejunum of the small intestine.
What is the primary site for the digestion and absorption of fats?
The small intestine.
What enzyme breaks down triglycerides into free fatty acids?
Pancreatic lipase.
Where are vitamins and minerals absorbed in the small intestine?
In the upper small intestine, except for B12 which is absorbed in the terminal ileum.
What is the clinical impression of the 25-year-old patient with acute watery diarrhea?
The patient has hyponatremia and severe dehydration indicated by markedly elevated BUN (prerenal azotemia).
What type of diarrhea is indicated by the patient’s continuous diarrhea despite negligible oral intake?
Secretory diarrhea.
Which infectious agents are common causes of secretory diarrhea?
- Cholera
- Certain Escherichia coli strains
What is the most common cause of acute gastroenteritis worldwide?
Rotavirus.
What does cholera toxin disrupt in the body?
The Na+/K+ ATPase pathway.
What are the two types of transport systems utilized for electrolyte absorption along the gastrointestinal tract?
- Electrogenic
- Electroneutral
How does electrogenic transport function in the intestine?
Involves translocation of net charge across the membrane, primarily through Na+/K+ ATPase and Na+/nutrient cotransporters.
What is the function of the Na+/glucose cotransporter (SGLT1)?
Transports Na+ along with glucose into the cell.
What regulates the activity of the epithelial Na+ channel (ENaC)?
Aldosterone and the cAMP signaling pathway.
What happens in electroneutral transport in the intestine?
It occurs through a Na+/H+ exchanger and is accompanied by Cl− transport via Cl−/HCO3− exchanger.
What is the role of the epithelial cells in the villi compared to those in the crypts?
Cells of the villi are responsible for absorption; cells of the crypts are responsible for secretion.
What is the primary mechanism for chloride secretion in the intestine?
Active transport using the Na+/K+/2Cl− cotransporter (NKCC1).
How is bicarbonate secretion regulated in the duodenum?
Through transporters such as the Cl−/HCO3− antiporter or CFTR.
What are secretagogues and their effect on CFTR activity?
Substances like acetylcholine, histamine, and cholera toxin that modulate chloride secretion via second messengers.
What is the mechanism of action of vasoactive intestinal peptide (VIP)?
VIP binds to receptors, stimulating adenylyl cyclase and increasing cAMP, leading to CFTR activation and chloride secretion.
What is chloridorrhea?
A rare inherited disease causing congenital diarrheal disorder due to mutations in the Cl−/HCO3− exchanger.
What is the net effect of cholera toxin on chloride secretion?
It causes uncontrolled secretion of chloride and sodium into the lumen, leading to diarrhea.
What is the mechanism of action of cholera toxin?
Cholera toxin binds to secretory epithelial cells, triggering endocytosis and releasing A subunit that modifies G protein Gsa through ADP-ribosylation, leading to constitutive stimulation of cAMP and uncontrolled secretion of chloride and sodium into the lumen.
What is secretory diarrhea?
An uncontrolled secretion of osmotically active particles, most often electrolytes, into the intestinal lumen, where secretion overwhelms absorption.
What are guanylins?
A class of intestinal natriuretic peptides that regulate water and electrolyte transport in the intestine and sodium excretion by the kidneys.
How do guanylins affect sodium reabsorption?
Guanylins decrease sodium reabsorption from the intestine and increase sodium secretion by the kidneys after a salty meal.
What is the primary signaling pathway for guanylins and heat-stable E. coli peptides?
Activation of guanylate cyclase C located at the apical membrane of enterocytes, increasing intracellular cGMP concentration.
What is the role of cGMP in chloride secretion?
Increased cGMP activates cGMP-dependent protein kinase II (PKGII), leading to phosphorylation of CFTR and promoting Cl− secretion.
How does calcium affect CFTR activity?
Calcium can induce CFTR activity, but this response is transient and smaller compared to cAMP and cGMP secretagogues.
What are the main components of the transport of fluid in the mucosal lining?
- Transcellular transport through apical and basolateral membranes in both small intestine and colon
- Intercellular space transport only in the small intestine
What is electrogenic transport?
Active transmembrane diffusion of sodium or chloride that results in a residual charge allowing subsequent transfer of chloride and water to equilibrate.
What is the Na+/H+ exchanger (NHE)?
A mechanism for electroneutral sodium transport in the small intestine and colon, usually coupled with Cl− transport via Cl−/HCO3− exchanger.
How is chloride transported across the basolateral membrane of crypt epithelial cells?
Using the Na+/K+/2Cl− cotransporter.
What is the role of CFTR in chloride secretion?
CFTR secretes chloride across the basolateral membrane and into the intestinal lumen, regulated by second messengers like cAMP, cGMP, and Ca2+.
What is the Roux-en-Y gastric bypass procedure intended to achieve?
To reduce stomach volume and bypass the duodenum, disrupting normal digestive pathways and decreasing absorption of macro and micronutrients.
What is dumping syndrome?
A condition caused by rapid gastric emptying resulting in osmotic diarrhea due to mal-digested contents being hyperosmolar.
What are the clinical manifestations of vitamin and trace mineral deficiencies in this case?
- Fatigue due to anemia
- Motor and sensory deficits in extremities
- Ataxia
- Positive Romberg test
What are the consequences of B12 deficiency?
Can lead to subacute combined degeneration in the spinal cord, encephalopathy, optic nerve damage, weakness, paresthesia, and ataxia.
What laboratory findings indicate deficiencies in this patient?
Borderline deficiencies of folate, B12, iron, and zinc, with a profoundly low serum copper level.
What is ceruloplasmin?
The major transporter of copper in the vascular space.
What causes the mixed morphology of red blood cells in this patient?
Combined deficiencies of vitamin and trace minerals leading to both macrocytosis and microcytosis.
What is the role of copper chaperones?
Small metalloproteins that move copper ions throughout the cell to protect from the redox potential of free copper ions.
What is the underlying pathology that leads to the need for bariatric surgery?
Obesity linked with comorbidities such as type 2 diabetes, hyperlipidemia, hypertension, obstructive sleep apnea, and obesity hypoventilation syndrome
The body mass index (BMI) is used to measure obesity.
What is the formula to calculate BMI?
Weight in kilograms divided by height in meters squared
What is considered a normal BMI range?
18.5 to 24.9 kg/m2
What are the BMI categories for overweight and obesity?
- Overweight: 25-29.9 kg/m2
- Class I Obesity: 30-34.9 kg/m2
- Class II Obesity: 35.0-39.9 kg/m2
- Class III Obesity: > 40 kg/m2
What are the recommendations for bariatric surgery according to NIH guidelines?
BMI ≥ 40 kg/m2 without comorbidities or BMI 35-39.9 kg/m2 with at least one comorbidity
What must patients undergo before bariatric surgery?
Psychological evaluation and assessment for lifelong lifestyle changes
What are the four common types of bariatric surgery procedures?
- Laparoscopic adjustable gastric banding
- Sleeve gastrectomy
- Duodenal switch with biliopancreatic diversion
- Roux-en-Y gastric
What are the three ways bariatric surgery leads to weight loss?
- Caloric restriction
- Iatrogenic malabsorption
- Combination of both
What is dumping syndrome?
Rapid gastric emptying causing food to move too quickly from the stomach to the small intestine
What are the two types of dumping syndrome?
- Early dumping
- Late dumping
When does early dumping occur and what are its symptoms?
Occurs within 10-30 minutes after a meal; symptoms include nausea, bloating, diarrhea, and vasomotor symptoms
What causes late dumping syndrome?
Exaggerated insulin response to excessive carbohydrate load, leading to reactive hypoglycemia
What vitamin and micronutrient deficiencies occur due to duodenal bypass?
Deficiencies in water-soluble vitamins and fat-soluble vitamins
What are the water-soluble vitamins?
- Thiamin (B1)
- Riboflavin (B2)
- Niacin (B3)
- Pyridoxine (B6)
- Folate (B9)
- Cobalamin (B12)
- Vitamin C
What is a key role of thiamine (B1)?
Production of energy
What can thiamine deficiency lead to?
Loss of appetite, irritability, confusion, and beriberi
What are the fat-soluble vitamins?
- Vitamins A
- D
- E
- K
What is the consequence of vitamin D deficiency?
Demineralization and osteopenia
What are essential trace minerals?
- Iodine
- Iron
- Copper
- Zinc
- Selenium
- Fluoride
- Cobalt
- Manganese
- Molybdenum
- Chromium
Which trace minerals are most affected by bariatric surgery?
- Iron
- Copper
- Zinc
What is the role of zinc in the body?
Involved in heme synthesis, DNA/RNA synthesis, reproduction, growth, immune function, and taste/smell
What can zinc deficiency lead to post-bariatric surgery?
Hair loss, diarrhea, emotional disorders, weight loss, concurrent infections, and dermatitis
What is noteworthy about the biochemistry of copper?
Integral part of oxidases, important for connective tissues, protects cells from reactive oxygen species, and involved in iron homeostasis
What happens if there is a deficiency of copper?
Hematological and neurological disorders such as anemia
What role does copper play in iron and zinc homeostasis?
Copper is involved in oxidizing iron from the +2 to the +3 state enabling incorporation into transferrin for transport in circulation.
What is ceruloplasmin?
Ceruloplasmin is the major copper-carrying protein in the blood.
What can result from copper deficiency after bariatric surgery?
Copper deficiency can lead to hematological and neurological disorders such as anemia and myeloneuropathy.
How much copper does the body contain?
The body contains about 100 mg of copper.
Where is copper absorbed in the body?
Copper is continually absorbed in the upper gastrointestinal tract.
What transporter facilitates copper absorption at the enterocyte level?
The CMT-1 transporter.
What is the principal transport vehicle for copper in circulation?
Ceruloplasmin transports 95% of copper in circulation.
What are the two notable genetic disorders related to copper absorption?
- Menkes disease
- Wilson disease
What causes Menkes disease?
Menkes disease is caused by a defect in the ATP7A gene leading to copper deficiency.
What are the symptoms of Menkes disease?
- Muscle weakness
- Developmental delay
- Seizures
- Kinky colorless hair
What characterizes Wilson disease?
Wilson disease is characterized by uncontrolled copper accumulation in tissues due to a defect in the ATP7B gene.
What are the symptoms of Wilson disease?
- Liver disease
- CNS symptoms
- Hemolysis
What is maldigestion?
Maldigestion refers to pancreatic exocrine insufficiency resulting in nutrient loss.
What is malabsorption?
Malabsorption refers to any disorder damaging the mucosal lining of the small intestine.
What is dumping syndrome?
Dumping syndrome is the postprandial presentation of undigested gastric contents into the small intestine.
What are the clinical sequelae of dumping syndrome?
- Hypoglycemia
- Diaphoresis
- Tachycardia
- Diarrhea
What is the significance of bariatric surgery in relation to malabsorption?
Bariatric surgery creates iatrogenic malabsorption, which has serious consequences.
What does carcinoid refer to?
Carcinoid describes tumors with a morphology that lacks classic malignancy characteristics.
What are enterochromaffin cells (EC)?
EC are specialized cells in the gut that produce serotonin in response to stimulation.
What is the function of enterochromaffin-like cells (ECL)?
ECL release histamine to stimulate parietal cells to secrete gastrin.
What are neuroendocrine tumors (NET)?
NETs are rare neoplasms involving cells responsive to neuronal control and hormone production.
What are the common symptoms of carcinoid syndrome?
- Flushing
- Diarrhea
- Bronchospasm
- Cardiac tricuspid valve disease
What laboratory tests should be ordered to clarify a suspected neuroendocrine tumor?
A random 4-hour urine collection for 5-HIAA and a CAT scan of the chest.
What is the pathophysiology of NETs?
NETs involve hormonally active substances that control bowel motility and secretion.
What is the role of enteroendocrine cells in the GI tract?
They produce hormones and neurotransmitters that regulate motility, digestion, and absorption.
What is the Zollinger-Ellison (ZE) syndrome?
ZE syndrome is caused by gastrin overproduction leading to excess acid production and peptic ulcers.
Where is gastrin located mainly in the body?
Stomach and pancreas
What stimulates the secretion of gastrin?
Rising pH of the stomach
What inhibits the secretion of gastrin?
Somatostatin
What can result from the overproduction of gastrin?
- Hyperactivity of parietal cells
- Hyperplasia of parietal cells
- Excess acid production
- Peptic ulcer formation
- Gastroesophageal reflux disease (GERD)
What are the common symptoms of gastrinoma?
- Abdominal pain
- GERD
- Chronic diarrhea
What is the result of hypersecretion of gastric acid?
Inactivation of pancreatic enzymes leading to steatorrhea
What suggests a gastrinoma on clinical presentation?
Recurrent or multiple gastric ulcerations in an Helicobacter pylori negative patient along with secretory diarrhea
What other neuroendocrine tumor syndrome is important to understand?
VIPoma (Verner-Morrison syndrome, pancreatic cholera, WDHA syndrome)
What causes VIPoma?
Hypersecretion of vasoactive intestinal peptide (VIP)
What are common symptoms of VIPoma?
- Diarrhea
- Electrolyte disturbances
What is the main hormone overproduced in carcinoid syndrome?
Serotonin
What role does serotonin play in the GI tract?
- Increases intestinal secretion
- Decreases absorption
- Decreases motility
What symptoms are associated with carcinoid syndrome?
- Flushing
- Diarrhea
- Bronchospasm
- Cardiac tricuspid valve disease
When do serotonin-like symptoms appear in carcinoid syndrome?
When the tumor has metastasized to the liver
What can excessive serotonin production lead to concerning tryptophan?
Depletion of tryptophan levels
What is tryptophan important for synthesizing?
- Serotonin
- Melatonin
- Niacin (vitamin B3)
What is the first step in serotonin synthesis?
Catalyzed by tryptophan hydroxylase
What is the end product of serotonin degradation?
5-hydroxyindoleacetic acid (5-HIAA)
What is a useful marker in the diagnosis of carcinoid syndrome?
5-HIAA levels in serum and urine
What medications are used to suppress serotonin effects in carcinoid syndrome?
- Octreotide
- Telotristat ethyl
What is the most common tumor of the appendix?
Carcinoid
What are common symptoms of lactose intolerance?
- Bloating
- Flatulence
- Diarrhea
What is a disaccharide?
Products of a condensation reaction between two monosaccharides
What are disaccharidases?
Brush border enzymes that hydrolyze disaccharides
What is a monosaccharide?
A sugar unit that cannot be further broken down
What is nonsense-mediated mRNA decay?
A pathway that selectively degrades mRNAs containing premature stop codons
What are reducing sugars?
Sugars that contain aldehyde groups that can be oxidized
What is the clinical impression when a patient presents with chronic secretory diarrhea?
Possibility of a rare but important neuroendocrine tumor
What is the relationship between IBS and more serious conditions?
IBS is a diagnosis of exclusion; more serious conditions should be ruled out first
What diagnostic tests are used for disaccharidase deficiency?
- Hydrogen breath test
- Oral tolerance tests
What happens when disaccharides are not digested?
They are metabolized by colonic bacteria leading to diarrhea and bloating
What is the hydrogen breath test used for?
To measure the amount of H2 produced from the gut, correlating with maldigestion from bacteria metabolizing lactose
This test is useful in diagnosing disaccharidase deficiencies.
What does an oral tolerance test measure?
The rise in blood glucose levels after challenging the patient with a suspected disaccharide
An absence or small rise in blood glucose suggests a disaccharide deficiency.
What is the purpose of measuring stool pH in the diagnosis of disaccharidase deficiencies?
To assess the acidity of stool, which can indicate malabsorption issues
A urine sample may also be used to monitor reducing sugars.
Which sugar is not a reducing sugar and cannot be diagnosed with Clinitest?
Sucrose
Clinitest can be used for lactose but not for diagnosing sucrase deficiency.
What is the most common type of lactose intolerance?
Primary, adult-onset hypolactasia
It affects about 65% of all adults and can reach 95% in certain ethnic groups.
What is congenital lactase deficiency?
A rare condition distinguished from adult-onset hypolactasia by its onset during breastfeeding
It is inherited in an autosomal dominant manner.
What genetic factor explains the two different phenotypes of lactose intolerance in adults?
A single nucleotide polymorphism
This affects the expression of the lactase gene.
What is secondary lactose intolerance?
Acquired lactose intolerance resulting from mucosal injury
Causes include gastroenteritis, celiac disease, and Crohn’s disease.
Which disaccharidase is most resistant to mucosal injury?
Maltase
It allows glucose absorption even in the presence of mucosal injury.
What is the common treatment for disaccharidase deficiencies?
Elimination or reduction of the specific sugar from the diet
Lactase supplements and lactose-free products are also available.
What is the relationship between lactase activity and symptoms of lactose intolerance?
Symptoms do not present until lactase activity drops below 50%
Lactase is not an inducible enzyme.
What is the effect of gut flora changes on lactose intolerance?
Tolerance can develop due to changes in gut flora
Most people can consume small amounts of milk without symptoms.
What are the key high-yield concepts related to disaccharidase deficiencies?
- Some degree of disaccharide deficiency is common in adults worldwide
- Diagnosis can be confounding with other conditions
- Lactose intolerance is a prototypical example of osmotic diarrhea with a secretory component.
What condition is characterized by the presence of coarse rales and bronchial breath sounds in a child?
Cystic fibrosis
It leads to pancreatic maldigestion and failure to thrive.
What nutrient deficiency is likely in a patient with neurological symptoms after gastric bypass surgery?
Vitamin B12
Symptoms include glossitis and neurological deficits.
How would you categorize the diarrheal illness characterized by fever, abdominal tenderness, and blood in the stool?
Inflammatory
This suggests an inflammatory disorder in the colon.
What laboratory test is useful for diagnosing a patient with melena and duodenal ulcers?
Serum gastrin level
This can indicate conditions like Zollinger-Ellison syndrome.
What is a typical symptom of explosive diarrhea after Roux-en-Y gastric bypass surgery?
Severe abdominal pain and urgency to defecate shortly after meals
This can be linked to changes in gut transit time.
What is the most likely diagnosis for a child with chronic diarrhea and positive Sudan stain for fecal fat?
Cystic fibrosis
This condition leads to malabsorption and fat maldigestion.
What is the likely cause of watery diarrhea in an infant with no blood or mucous in stools?
Lactose intolerance
This may occur after the introduction of solid foods.
What is the pathogenesis of diarrhea due to Vibrio cholerae?
Overactivation of the alpha subunit of Gs-proteins
This leads to increased cAMP and subsequent electrolyte secretion.
What is the typical presentation of an inflammatory disorder in the colon?
Fever, abdominal tenderness, blood in the stool, chronic diarrhea, lower abdominal cramplike pain, urgency, incontinence
These symptoms suggest an inflammatory picture rather than osmotic or motility disorders.
What distinguishes osmotic diarrheal syndromes from inflammatory disorders?
Osmotic diarrheal syndromes typically present with bulky, watery fecal material that is controllable and ceases with fasting
In contrast, inflammatory disorders persist regardless of food intake.
What is Zollinger-Ellison (ZE) syndrome characterized by?
Elevated gastrin levels, recurrent ulcer disease, multiple ulcerations, malabsorption due to diarrhea
It is a type of neuroendocrine tumor (NET).
What should be considered when taking a dietary history for gastrointestinal symptoms?
Possible dietary indiscretion, consumption of caffeine or milk
A careful dietary history can help identify triggers for symptoms.
What laboratory findings indicate celiac disease?
Elevated levels of IgA antihuman tissue transglutaminase, IgA antiendomysial antibodies
These findings are critical for the diagnosis of celiac disease.
What is congenital chloride diarrhea (CCD)?
Defective intestinal absorption of Cl− and secretion of HCO3−, leading to hypochloremia, hypokalemia, hyponatremia, metabolic alkalosis
It results in high stool chloride and sodium levels.
What causes dumping syndrome?
Rapid gastric emptying and duodenal bypass leading to maldigestion, hyperosmolarity, and osmotic diarrhea
Symptoms arise due to fluid shifts from the intravascular space to the intestinal lumen.
What is sucrase deficiency and how is it diagnosed?
Deficiency causing diarrhea with the introduction of fruits and vegetables; diagnosed by negative reducing sugar test
Sucrose is not a reducing sugar, hence a negative result is expected.
How does Vibrio cholerae cause secretory diarrhea?
Secretes a toxin that activates the alpha subunit of Gs-proteins, increasing cAMP and causing chloride and water efflux
This leads to substantial secretory diarrhea.
True or False: The diarrhea caused by cystic fibrosis is typically watery.
False
Cystic fibrosis leads to bulky, foul-smelling, greasy stools due to maldigestion and malabsorption.
Fill in the blank: The presence of fever, rectal bleeding, and abdominal tenderness would likely rule out _______.
Motility disorders
These symptoms are not characteristic of motility disorders like irritable bowel syndrome.
What are the symptoms of celiac disease?
Distended abdomen, colic, irritability
These symptoms can vary but are often associated with malabsorption.
