Download Coeliac disease

MALABSORPTION SYNDROME
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Learning objectives
Understand definition of malabsorption.
Discuss causes and mechanism of malabsorption.
Discuss commonest diseases associated with malabsorption
Malabsorption syndrome
Malabsorption syndrome is an alteration in the ability of the intestine to
absorb nutrients adequately into the bloodstream. It may refer to
malabsorption of one specific nutrient or for specific carbohydrates, fats, or
trace elements (micronutrients).
-Impairment can be of single or multiple nutrients depending on the
abnormality.
-This may lead to malnutrition and a variety of anaemias.
Malabsorption syndrome
Malabsorption constitutes the pathological interference with the normal
physiological sequence of digestion (intraluminal process), absorption
(mucosal process) and transport (postmucosal events) of nutrients.
Intestinal malabsorption can be due to:
1. digestive failure caused by enzyme deficiencies
2. structural defects
3. mucosal abnormality
4. infective agents
5. systemic diseases affecting GI tract
Causes:
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Due to digestive failure:
Pancreatic insufficiencies:
cystic fibrosis
chronic pancreatitis
carcinoma of pancreas
Bile salt insufficiency:
obstructive jaundice
bacterial overgrowth
2. Due to structural defects:
•Inflammatory bowel diseases commonly: Crohn's Disease
• Gastrectomy and gastro-jejunostomy
• Fistulae, diverticulae and strictures.
• Infiltrative conditions such as amyloidosis, lymphoma.
• Eosinophilic gastroenteropathy.
• Radiation enteritis.
• Systemic sclerosis and collagen vascular diseases.
• Short bowel syndrome.
3. Due to mucosal abnormality:
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Coeliac disease
4. Due to enzyme deficiencies:
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Lactase deficiency inducing lactose intolerance
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Disaccharidase deficiency
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Enteropeptidase deficiency
5. Due to infective agents:
-Whipple's disease
-Intestinal tuberculosis
-Tropical sprue
-Parasites e.g. Giardia lamblia.
6. Due to other systemic diseases affecting GI tract:
-Hypothyroidism and hyperthyroidism
-Diabetes mellitus
-Hyperparathyroidism and Hypoparathyroidism
-Carcinoid syndrome
-Malnutrition.
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Clinical picture:
Symptoms can be intestinal or extra-intestinal - the former predominates
in severe malabsorption.
Diarrhoea, often steatorrhoea is the most common feature. It is due to
impaired water, carbohydrate and electrolyte absorption.
Latter also results in bloating, flatulence and abdominal discomfort.
Weight loss
Growth retardation, failure to thrive, delayed puberty in children
Swelling or edema from loss of protein
Anaemias, commonly from vitamin B12, folic acid and iron deficiency
presenting as fatigue and weakness.
Muscle cramp from decreased vitamin D, calcium absorption. Also lead
to osteomalacia and osteoporosis
Bleeding tendencies from vitamin K and other coagulation factor
deficiency.
Management of malabsorption syndrome:
Replacement of nutrients, electrolytes and fluid may be necessary.
In severe deficiency, hospital admission may be required for parenteral
administration.
Pancreatic enzymes are supplemented orally in pancreatic
insufficiency.
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Dietary modification is important in some conditions:
– Gluten-free diet in coeliac disease.
– Lactose avoidance in lactose intolerance.
Antibiotic therapy will treat Small Bowel Bacterial overgrowth.
COMMON MALABSORPTIONS
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Lactose intolerance
lactose is the only disaccharide carbohydrate present in milk
Lactose essential for survival of an infant
the enzyme lactase is essential for babies
an adult deficiency disease
Ingestion of milk in these individuals causes nausea, diarrhoea and
stomach cramps.
Symptoms disappear if milk is excluded from the diet or
if a source of lactase is ingested along with or before ingestion of milk
The bacteria that are involved in the production of yoghurt contain the
enzyme lactase
Coeliac disease
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results in an immune response in the intestine to the protein gliadin
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a constituent of the germ of wheat, barley, oats and rye
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Sensitivity to gliadin arises through stimulation of B-lymphocytes
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produce antibodies of class E which activate mast cells
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toxic compounds released from mast cells results in loss of villi
especially in the proximal part of the small intestine
Symptoms
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pale, bulky, loose, offensive stools
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abdominal distortion and discomfort
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caused by failure of the small intestine to digest a considerable
proportion of the food which then passes into the colon where it is
fermented.
Treatment
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gluten-free diet
Sprue (post-infective malabsorption)
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The healthy small intestine contains only a small bacterial population,
unlike the colon
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an acute infection of the mucosa by a virus, bacterium or other parasite
can reduce its motility, allowing a huge proliferation of the
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resident bacteria.
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Absorption of both macro- and micronutrients is impaired, resulting in
the disorder known as sprue
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Folic acid is particularly poorly absorbed, causing reduced rates of
repair of mucosal cells
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Damage persists and worsens to create a vicious circle
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clinical presentation includes bulky stools, steatorrhoea (fatty faeces)
and weight loss.
Treatment
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involves administration of an antibiotic to kill the bacteria and folic acid to
allow damaged tissue to recover
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Crohn’s disease
segments of the intestine suffer chronic inflammation
The cause is unknown but it may be an autoimmune disease.
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