Malabsorption And Malnutrition

Question 1

What is malnutrition

Answer 1

Insufficient dietary intake to meet metabolic requirements

Question 2

What is malabsorption

Answer 2

Disorder of the digestive tract resulting in ability to utilise an appropriate dietary intake

Question 3

What structures are designed for digestion?

Answer 3

Mouth
Stomach 
Pancreas
Biliary 
Small intestine

Question 4

What is the role of the mouth for digestion?

Answer 4

Mastication
Lubrication
Taste
Digestion
o Parotid, submandibular, submaxillary salivary glands o Amylases
o Lipases

Question 5

What is the role of the duodenum in digestion

Answer 5

• Chyme passed into duodenum
• Digestive juices from pancreas secreted
• Bile acids needed for emulsifications of fat

Question 6

What is the role of the exocrine pancreas?

Answer 6

Amylase
Lipase
Proteolytic enzymes
Regulated secretion into the duodenum

Question 7

What is the role of bile in digestion?

Answer 7

Emulsifies fats

Micelle formation – hydrophobic/hydrophilic elements

Question 8

How long is the small intestine

Answer 8

4-6 m

Question 9

What is the role of the jejunum?

Answer 9

Rapid digestion and absorption of macronutrients

Virtually all absorption complete ion distal jejunum

Question 10

What is the role of the ileum?

Answer 10

Intestinal contents: indigestible carbohydrate (fibre), bile acids and vitamin B12, IF
Specialised transport systems for bile acids and vitamin B12, IF in distal ileum

Question 11

What is the role of villus?

Answer 11

Surface area for absorption
Microvilli
Enzyme production
Leaky mucous membrane
Specific transport mechanisms o Vascular counter-current arcade o Lymphatic channels

Question 12

What are enterocytes?

Answer 12

Polarised cells – apical and basolateral membranes, electrochemical gradients o Intercellular spaces/junctions
Specific transport pathways for glucose, amino acids, lipids etc.

Question 13

How are malabsorptive diseases diagnosed based on?

Answer 13

The diseased organ
The disease specific deficiency
The malabsorbed food

Question 14

Where can diseases of the small intestine occur?

Answer 14

Luminal – infections, bacterial overgrowth
Mucosal- Loss of absorptive surface area – Crohn’s disease, surgery, lymphoma, Degeneration of absorptive surface area – coeliac disease (1/100 people approx.)
Post mucosal - lymphangiectasia

Question 15

What are luminal infections?

Answer 15

Giardiasis – bloating, steatorrhoea (fatty poo)
TB
Ancylostoma – Fe deficiency
Tropheryma whippelii – subtotal villous atrophy
Cryptosporidium, microsporidium, isopera (AIDS)

Question 16

give examples of luminal bacterial overgrowth?

Answer 16

Jejunal diverticulosis (weak outpouching of mucosa which bacteria colonise)

Blind loop syndrome
o Surgical, fistulation
o Section of bowel plumbed in and there is a redundant blind ending loop, making it a good area for bacteria to grow

Obstruction

Motility disorders
o Autonomic neuropathy (diabetes) – NS to bowel disordered and reduced peristalsis occurs
o Scleroderma – connective tissue disorder impairing bowel motility

Hypochlorhydria in the elderly

Question 17

What is coeliac disease

Answer 17

Gluten enteropathy
Immune mediated – direct inflammatory response to gluten, flattens villi, loss of SA for absorption
Subtotal villous atrophy
Crypt hyperplasia
Intraepithelial lymphocytes
Loss of surface area and villus maturation
Autoantibodies
o Anti-tissue transglutaminase (endomysial) – best test to identify coeliac disease
Coeliac disease leads to substrate deficiency due to degeneration of absorptive surface area:
o Fe deficiency
o Folate deficiency o Osteomalacia

Question 18

Where does 95% of bile salt absorption take place?

What is bile salt malabsorption called?

Answer 18

Terminal ileum

Bile Salt catharsis

Question 19

What are the consequences of B12 malabsorption?

What is needed for B12 absorption

Answer 19

Megaloblastic anaemia
Peripheral neuropathy o Optic atrophy
Dementia
SACD

Intrinsic factor is needed for B12 absorption

Question 20

Give examples of biliary disease?

Answer 20

Obstructed bile drainage (Intrahepatic/Extrahepatic)

ADEK malabsorption
o Coagulopathy
o Osteomalacia
o Ataxia
o Night blindness, xerophthalmia

Question 21

What is the main cause of chronic pancreatitis?

Answer 21

Alcohol

Question 22

What is Zollinger-Ellison syndrome?

Answer 22

Due to a neuroendocrine tumour causing excess gastric acid secretion
Can be due to MEN 1
Primary tumour usually in pancreas, duodenum

Question 23

Give examples of malnutrition?

Answer 23

Protein energy malnutrition (PEM)

Specific nutrient malnutrition

Question 24

Describe PEM in the developing world

Answer 24

Predominantly protein lack-Kwashiorkor (protein deficiency causing oedematous appearance)

Total dietary lack (caloric)-Marasmus (deficiency in calories and energy)

• Growth failure
• Apathy
• Diarrhoea
• Hepatomegaly
• Muscle wasting
• Oedema
• Anaemia
• Stomatitis

Question 25

What are the causes of PEM in the UK?

Answer 25

Anorexia (suppression of appetite) o Malignancy (cytokines) o Infection/inflammation (e.g. TB, AIDS) o Anorexia nervosa (mental illness) Neglect o Elderly (tea and toast) o Hospitalised o Neurological disease (e.g. MND affects swallowing) Dysphagia (inability to swallow) ``` Increased metabolic demands o Thyrotoxicosis (thyroid disease) ```

Question 26

What are the specific malnutrition’s common in the UK?

Answer 26

Iron deficiency - microlytic, hypochromic anaemia - menses, vegetarians Vit B complex -neuropathy ( B6), cardiomyopathy and encephalopathy (B1), stomatitis (B2), pellagra (niacin) Folic acid - megaloblastic anaemia - pregnancy (neural tube defect) Vit D - osteomalacia, rickets - Indian sub continent diet and lack of UV B12 - Megaloblastic anaemia - Neuropathy - SACD (subacute combined degeneration of the spinal cord) o Ataxia - Dementia Vitamin C -Scurvy/Rickets Vitamin K -Coagulopathy