Pancreatic Disorders and GI Tract Functions

Pancreatic Disorders

• Pancreatic disorders include acute pancreatitis, chronic pancreatitis, carcinoma of the pancreas, and cystic fibrosis.
• Acute pancreatitis is a sudden inflammation of the pancreas lasting a short time without permanent damage. It can range from mild discomfort to a severe, life-threatening illness.
• Chronic pancreatitis involves progressive, irreversible morphological changes and gradual fibrotic replacement of the pancreatic tissue
• Carcinoma of the pancreas is a cancer of the pancreas, often found in the head of the pancreas, detectable earlier and with a lower survival rate.
• Cystic fibrosis is a genetic disorder primarily affecting the lungs, but also the pancreas, liver, kidneys, and intestine. It's characterized by mucus and exocrine gland dysfunction due a mutation in CFTR protein.

Functions of the GI Tract

• Digestion
• Absorption
• Synthesis of paracrine hormones
• Controlling gut motility
• Release of digestive enzymes

Carbohydrate Digestion and Absorption

• Digestion and absorption of polysaccharides (CHO) depend on normal pancreatic function.
• The digestion of carbohydrates begins with amylase, breaking down polysaccharides like amylose and amylopectin.
• Brush border enzymes such as sucrase, isomaltase, maltase, and lactase further break down disaccharides and oligosaccharides, aiding in the absorption of simples sugars within the small intestine.

Protein Digestion and Absorption

• Protein digestion is initiated by pepsinogen, converted to pepsin, in the stomach.
• Pancreatic enzymes such as trypsin, chymotrypsin, and carboxypeptidase play critical roles in protein breakdown in the small intestine, converting polypeptides into small peptides and amino acids.

Lipid Digestion and Absorption

• Lingual lipase (lingual glands) and gastric lipase are important in breaking down triglycerides containing short and medium-chain fatty acids, significantly impacting milk fat digestion in infants.
• Bile salts, released from the gallbladder stimulated by CCK, emulsify lipids, increasing surface area for the pancreatic lipase to act.
• Micelles form, facilitating lipid absorption. The emulsified fats then form into micelles for proper absorption and transport to blood.
• Triglycerides are reformed in mucosal cells, packaged into chylomicrons, and released into the lymphatic system.

Pancreatic Juice

• Pancreatic juice is a mixture of enzymes and buffers (sodium bicarbonate).
• It is secreted by acinar cells into the pancreatic duct and released into the duodenum.
• Pancreatic juice contains amylase for starch digestion and proteases (trypsin, chymotrypsin, carboxypeptidase) for protein breakdown.
• It also contains lipase for lipid digestion and nucleases for RNA and DNA digestion.
• Sodium bicarbonate neutralizes acidic chyme, creating the alkaline pH needed for enzyme function in the small intestine.

Cystic Fibrosis Manifestations

• Intestinal obstruction in newborns
• Excessive pulmonary infections in children
• Pancreatogenous malabsorption in adults

Cystic Fibrosis Diagnosis

• Sweat test measuring chloride levels; >60 mEq/L indicates cystic fibrosis.

Pancreatic Disease Diagnostic Tests

• Blood tests (amylase, lipase, trypsin)
• Secretin Stimulation Test (pancreas' response to secretin)
• Fecal Elastase Test
• Imaging studies (CT scan, abdominal ultrasound, ERCP, Endoscopic ultrasound, MRCP)

Serum Amylase

• An enzyme produced by the pancreas primarily.
• Used for diagnosing pancreatitis.
• Not specific enough for diagnosis (can have elevated levels in other diseases.)

Amylase and Lipase in Acute Pancreatitis

• Lipase is more specific for diagnosing acute pancreatitis.
• Levels rise within 4-8 hours of symptom onset and return to normal within a week, reaching 3 times the normal limit to confirm the diagnosis.
• Amylase, while less specific, also rises within 4-8 hours after the onset, but can be elevated in other conditions.

Secretin/CCK Test

• Measures the exocrine capacity of the pancreas.
• Involves intubation, fasting for 6 hours, and I.V. administration of secretin and CCK to stimulate pancreatic secretions.
• Collected secretions are tested for pH, enzymatic activity (trypsin, amylase, lipase), and bicarbonate amounts.
• Low levels of these indicate possible pancreatic obstruction or disease.

Malabsorption

• A decrease in the ability to digest or absorb nutrients.
• Includes disturbances in electrolyte, water, vitamin (especially fat-soluble), and mineral absorption.
• Seen in various diseases, potentially leading to general malnutrition and symptoms in specific nutrients like vitamin B12 and lactose.

Causes of Malabsorption

• Digestive problems such as bile insufficiency and pancreatic enzyme insufficiency.
• Absorption issues impacting intestinal cells or tissues, shortened intestines, and lymphatic system problems.
• Cystic fibrosis may also cause malabsorption.

Signs and Symptoms of Malabsorption

• Includes general symptoms like weight loss (despite normal appetite), pale stool, diarrhea (often greasy offensive in fat malabsorption), edema, muscle atrophy, and amenorrhea.
• Also encompasses specific nutrient deficiencies: vitamin A, D, E, K, B12, folic acid, iron, calcium, and vitamin D.
• Manifestations vary based on the affected nutrient and disease entity.

Carbohydrate Malabsorption

• Results in defects of disaccharidases, hereditary or acquired conditions.
• Lactose intolerance is a type of carbohydrate malabsorption, often due to lactase deficiency causing excess gas, abdominal pain, and diarrhea.
• Tolerance testing (hydrogen, H₂) is often conducted to diagnose.

Protein Malabsorption

• Results from pancreatic failure (enzyme dysfunction).
• Secondary protein malabsorption is frequently seen in chronic pancreatitis, cystic fibrosis, and pancreas removal surgeries.

Protein Losing Enteropathy

• Results from excessive plasma protein loss into the gastrointestinal lumen.
• Leads to hypoalbuminemia, generalized edema, and ascites.
• Factors associated with protein losing enteropathy include: Celiac disease, Crohn's disease, short bowel syndrome and others.

Kwashiorkor

• Results when insufficient protein is present in the diet.
• Primarily affects slightly older children.
• Leads to edema, fatty liver, anemia, and reduced immune function, increasing risk for infections.

Lipid Malabsorption

• Loss of fats in the stool (steatorrhea).
• Deficiencies in vitamins (A, D, E, and K). A critical element of malabsorption.
• Often connected to pancreatic problems, bile issues, intestinal problems, and nutritional deficiencies.

Fecal Fat Determination

• Used to diagnose lipid malabsorption.
• 3-day stool collection and fat measurement; >7g/day is abnormal (steatorrhea).

• 14g/day, further investigation might be required (PERT).

Lactose Intolerance

• Results from lactose maldigestion in the small intestine. This can lead to problems in the colon due to bacterial fermentation of the undigested lactose, causing symptoms like bloating, gas, diarrhea, and abdominal discomfort.
• Diagnosis includes: hydrogen breath test, lactose tolerance blood test, stool acidity test, and enzyme measurement/genetic mutation.

Lactase Deficiency

• Commonly occurs later in life, 35% of adults experiencing some form.
• Primary lactase deficiency is genetically determined.
• Secondary lactase deficiency arises from underlying diseases or conditions.
• Congenital lactase deficiency occurs in newborns.

This quiz covers pancreatic disorders, including acute and chronic pancreatitis, pancreatic carcinoma, and cystic fibrosis. It also explores the essential functions of the gastrointestinal tract, such as digestion, absorption, and hormone synthesis. Test your knowledge on these critical topics related to human health.