• Malabsorption syndrome:
• Objectives:• Malabsorption syndrome:
• Definition.
• Causes.
• Celiac disease:
• Pathogenesis.
• Clinical Manifestations.
• Investigations.
• Treatment.
• Malabsorption syndrome:
• Definition:• Malabsorption syndrome refers to a number of disorders in which the intestine can’t adequately absorb certain nutrients into the bloodstream. It include the absorption of macronutrients (proteins, carbohydrates, and fats), micronutrients (vitamins and minerals), or both.
• Causes:
• Malabsorption due to generalized mucosal defect:• Food induced enteropathy e.g. celiac disease , cow's milk and other protein sensitive enteropathy.
• Congenital bowel mucosal defects e.g. microvillous inclusion disease.
• Protein losing enteropathy e.g. lymphangiectasia, disorders causing bowel mucosal inflammation.
• Infection induced e.g. parasitic infection especially giardiasis, bacterial overgrowth, tropical sprue and postinfectious enteropathy.
• Immunodeficiency disorders e.g. congenital or acquired immunodeficiency disorders, immunosuppressive therapy.
• Miscellaneous e.g. short bowel syndrome, chronic malnutrition and radiation enteritis.
• Malabsorption due to predominant nutrient malabsorption:
• Carbohydrate malabsorption e.g. lactose malabsorption, congenital lactase deficiency, congenital sucrase- isomaltase deficiency.• Fat malabsorption e.g. pancreatic exocrine insufficiency, cystic fibrosis, shwachman-diamond syndrome, chronic pancreatitis, protein-callorie malnutrition, liver and biliary disorders.
• Amino acid malabsorption e.g. hartnup disease ( defect in free neutral amino acids ), blue diaper syndrome ( isolated tryptophan malabsorption ).
• Minerals and vitamins malabsorption e.g. congenital chloride diarrhea, congenital sodium absorption defect, acrodermatitis enteropathica ( zinc malabsorption ), menke disease ( copper malabsorption ), folate malabsorption and vitamin B12 malabsorption.
• Drug-induced malabsorption e.g. sulfasalazine ( folic acid ), phenytoin ( calcium ) and cholestyramine ( calcium and fat ).
• CELIAC DISEASE
• ( GLUTEN- SENSITIVE ENTEROPATHY )• It is a common disease that found in at least 1% of population. The concordance in monozygotic twins approaching 100%, but the incidence in HLA identical siblings about 30-50 % and in HLA non identical siblings about 2-5 % . The vast majority of people with coeliac have one of two types of the HLA-DQ protein.
• Pathogenesis:
• It is an autoimmune-mediated enteropathy caused by permanent sensitivity to gluten in genetically susceptible individuals, although environmental factors also play a role. Gluten protein is found in wheat, rye, barly and infrequently oat, it react with transglutaminase enzyme in the gut and it is a potent inducer of T- cell lines.The inflammatory process, mediated by T cells, leads to disruption of the structure and function of the small bowel's mucosal lining and causes malabsorption as it impairs the body's ability to absorb nutrients, minerals and vitamins from food
• Clinical Manifestations:
• History:
• Typical presentation usually within first 2 years of life after introduction of gluten in the diet, it include one or more of the following:-
• FTT.
• Diarrhea.
• Vomiting.
• Irritability.
• Anorexia ( sometimes increase appitite ).
• Abdominal pain and distention.
• Loose, bulky and foul-smell stools.
• Rarely, rectal prolapse.
• Examination:
• Decrease growth parameters.• Muscles wasting and hypotonia.
• Abdominal distention.
• Edema.
• Rarely, clubbing of fingers.
• Extra-intestinal manifestations and associations with celiac disease:
• Iron deficiency anaemia, hypoplasia of permanent teeth, osteoporosis, short stature, delayed puberty, hepatitis, arthritis, headache, epilepsy and depression.• Autoimmunity e.g. type 1 DM, thyroiditis, Addison disease and IgA deficiency.
• Syndromes e.g. Turner, Down and William.
• Malignancy ( if untreated ) e.g. adenocarcinoma and NHL of small bowel.
• Investigations:
• Blood test:
• Anti-transglutaminase IgA antibody and anti-ndomyseal IgA antibody are highly sensitive and specific tests but measurement of serum IgA concentration is manditary to exclude false-negative results if celiac disease is associated with IgA deficiency, which if present we have to shift to anti-transglutaminase IgG antibody ( instead of IgA ) and anti-endomyseal IgG.
• Note: These antibodies should decrease after withdrawal of gluten from diet.
• Small intestinal biopsy:
• It is the definitive test for celiac disease but since mucosal involvement is usually patchy, so multiple biopsies should be obtained. Histologic changes include partial or total villous atrophy, crypt elongation and increase number and mitotic index of lymphocytes.• Because of the presence of conditions that can produce similar histologic changes, therefore 2 biopsies are required for diagnosis:
• Initial biopsy at presentation and the second biopsy to document healing on gluten withdrawal from the diet, although this may not be required when there is good clinical and biochemical response to gluten-free diet, as well as gluten challenge is currently not considered mandatory except in situations when there is doubt about initial diagnosis.
• Genetic test:
• The absence of HLA DQ2 and/or HLA DQ8 have a stronge negative predictive value for diagnosis of celiac disease, whereas their presence have very weak positive predictive value.• Treatment:
• The only treatment for celiac disease is life-long gluten-free diet which require exclusion of wheat, barley and rye as well as unpurified oat.• After gluten withdrawal, a rapid remission of symptoms will occur ( within one week ) and level of transglutaminases should also decrease after six months of gluten withdrawal.