The document discusses malabsorption and maldigestion, detailing their distinct pathophysiological mechanisms and interdependence in nutrient absorption. It covers clinical features, diagnostic approaches, specific disorders, and treatment strategies related to malabsorption in various conditions such as celiac disease, IBD, and congenital defects. Key diagnostic methods include stool tests, biopsies, and clinical assessments, while treatment focuses on addressing nutrient deficiencies and underlying causes.

1. MALABSORPTION
Dr Arun Aggarwal
Gastroenterologist

2. INTRODUCTION
 Malabsorption refers to impaired absorption of nutrients.
 Maldigestion: impaired digestion of nutrients within the intestinal
lumen or at the terminal digestive site of the brush border
membrane of mucosal epithelial cells.
 Although malabsorption and maldigestion are
pathophysiologically different, the processes underlying digestion
and absorption are interdependent.

3. INTRODUCTION
 Three steps are required for normal nutrient absorption :
 Luminal and brush border processing.
 Absorption into the intestinal mucosa.
 Transport into the circulation.
 Disruption in any of the 3 processes above can result in
malabsorption.
 May be due to congenital defects in the membrane transport
systems of the small intestinal epithelium or from acquired
defects in the epithelial absorptive surface.

5. MALABSORPTION DUE TO GENERALIZED
MUCOSAL DEFECT

6. MALABSORPTION DUE TO GENERALIZED
MUCOSAL DEFECT

7. CLINICAL FEATURES
 Depend on the extent and type of the
malabsorbed nutrient.
 May be global as in Celiac disease or
partial due to specific nutrient
malabsorption as in Vitamin B12
deficiency.
 Symptoms: Chronic diarrhea,
anorexia, flatulence, abdominal
distention, IBS like sx, failure to gain
weight, a fall in growth chart
percentiles.
 Signs:
 muscle wasting, loss of
subcutaneous fat with subsequent
loose skin folds.
 Edema is usually associated with
protein-losing enteropathy.

8. CLINICAL FEATURES
Signs:
 Perianal excoriation and gaseous abdominal distention with
carbohydrate malabsorption.
 Perianal and circumoral rash with acrodermatitis enteropathica.
 Abnormal hair with Menkes syndrome.
 Digital clubbing with cystic fibrosis and celiac disease.
 Osteopenia or increased risk of fractures due to celiac disease or
fat-soluble vitamin deficiency.
 The nutritional consequences of malabsorption are more dramatic in
toddlers because of the limited energy reserves and higher
proportion of calorie intake being used for weight gain and linear
growth.
 If malabsorption is untreated, linear growth slows, and with
prolonged malnutrition, death can follow.

9. DIAGNOSIS
 History:
 onset of diarrhea- at birth or early infancy or later childhood
 nature of the diarrhea- explosive diarrhea in CHO malabsorption
or foul-smelling, greasy large volume stools in CF.
 after introduction of a particular food as in celiac disease or
CMPI.
 ROS - abdominal pain, weight loss, joint pains, rashes
 Family History
 Physical examination for signs of specific nutrient malabsorbed.
 Plot growth parameters.

10. DIAGNOSIS
 Routine labs:
 Stool for culture, O & P, Guaiac, wbc’s - r/o Inflammatory disease or
Infection.
 Stool pH, reducing substances- CHO malabsorption.
 Stool Giardia Antigen.
 Stool for qualitative fat on a random specimen and later may need
72hr stool for quantitative fat- steatorrhea.
 CBC and Peripheral smear for Acanthocytes – Abetalipoproteinemia,
Neutropenia – Schwachman syndrome.
 Anti-endomysial Ig A and Ig G, Anti-TTG Ig A and Ig G (specially
in Ig A deficient patients), Serum Ig A – Celiac disease.
 Specific tests for CHO, fat, protein, vitamin/mineral malabsorption.

11. BASED ON PREDOMINANT NUTRIENT
MALABSORBED
 Presence of acidic stool, > 2+
reducing substances with a hx
of explosive diarrhea.
 Breath H2 tests for lactose,
fructose or sucrose
malabsorption.
 Specifically, small bowel
mucosal biopsies to test for
disaccharidase levels.
 Primary deficiency:
enzyme levels low with
normal villous
morphology.
 Secondary deficiency: low
enzyme levels with partial
or total villous atrophy.

12. BASED ON PREDOMINANT NUTRIENT
MALABSORBED
 Assess for stool fat- age dependent:
preterm: 65-70% absorbed, full-
term: 90% dietary fat absorbed,
older children > 95% absorbed.
 Start with random stool specimen
for qualitative fat by Sudan stain or
for fat globules. (Gold std is a 72hr
stool for fat).
 Patient should eat 70-120g/day fat
in diet: >14g/day stool fat is
abnormal.
 Stool fat concentration > 8% -
pancreatic exocrine insufficiency.
 Look for underlying cause: CF-
sweat chloride test, Low serum
cholesterol, TG and VLDL, LDL in
Abetalipoproteinemia, Vitamin
ADEK levels, PT.

13. BASED ON PREDOMINANT NUTRIENT
MALABSORBED
 Hypoalbuminemia – check urine
proteins (renal disease), liver
disease/decreased intake.
 Stool Alpha-1 antitrypsin for
PLE.
 Signs of Nicotinamide
deficiency due to low tryptophan
levels in Hartnup disease:
dermatitis, diarrhea, dementia
and death.

14. BASED ON PREDOMINANT NUTRIENT
MALABSORBED
 Stool for Na and Chloride levels,
check osmotic gap of stool.
 Zinc and ALP levels
 Ceruloplasmin and Copper
 Serum B12 and FA, Anti-parietal cell
antibodies, IF levels.
 EGD and colonoscopy for IBD,
Celiac disease
 Imaging studies: non-specific.
 Histology for Microvillous inclusion
disease, tufting enteropathy.
 Pancreatic exocrine insufficiency:
sweat test(CF), Stool elastase, Serum
trypsinogen- screen- low in
Pancreatic insufficiency in CF and
Schwachman syndrome.
 Gold std: Duodenal aspirate for
HCO3, trypsinogen, lipase after
secretin and CCK stim.

15. MALABSORPTION DUE TO CONGENITAL
MUCOSAL DEFECT

16. DIAGNOSIS OF INTESTINAL MUCOSAL
DISORDERS
 Histologic examination of small
bowel mucosal biopsies.
 Mucosal involvement can be
patchy, especially in celiac disease
and intestinal lymphangiectasia.
 Periodic acid–Schiff (PAS)
staining of mucosal biopsies and
electron microscopy are necessary
in congenital diarrhea to assess
congenital microvillus atrophy.
 Autoimmune enteropathy: Sx
occur after the 1st 6 mo of life
with chronic diarrhea,
malabsorption, and failure to
thrive.

17.  In contrast to gluten-sensitive enteropathy, an increase in intra-
epithelial lymphocytes is not a prominent feature of autoimmune
enteropathy.
 Specific serum anti- enterocyte antibodies can be identified in ≥50%
of patients by indirect immunofluorescent staining of normal small
bowel mucosa and kidney.
 Extra intestinal autoimmune disorders are usual.
 Exclude underlying primary immune deficiency, particularly in boys
with other autoimmune features (diabetes mellitus), because a
proportion have underlying Immune dysregulation,
Polyendocrinopathy, Enteropathy, X linked (IPEX) syndrome.
 Treatment: immune suppression drugs including prednisone,
azathioprine, cyclophosphamide, cyclosporine, and tacrolimus.
 Bone marrow transplantation is curative for children with IPEX
syndrome.

18. BILE ACID MALABSORPTION
 Primary bile acid malabsorption -
mutation of the ileal sodium–bile
acid co transporter gene.
 Secondary bile acid
malabsorption - ileal disease,
such as in Crohn disease, and
following an ileal resection.
 Presents as congenital diarrhea,
steatorrhea, interruption of
enterohepatic circulation of bile
acids, and reduced plasma
cholesterol levels.
 Treatment: restriction of dietary
fat, cholestyramine - an anion-
binding resin.

19. BACTERIAL OVERGROWTH
 Gastric acid pH, small bowel motility and the migrating motor
complex, the ileocecal valve, mucosal defenses such as mucin and
immunoglobulins prevent bacterial overgrowth in the small bowel.
 Bacterial overgrowth can result from clinical conditions that alter
the gastric pH or small bowel motility, including disorders such as
partial bowel obstruction, diverticula, short bowel, intestinal
duplications, diabetes mellitus, idiopathic intestinal pseudo-
obstruction syndrome, and scleroderma.
 Prematurity, immunodeficiency, and malnutrition are other factors
associated with bacterial overgrowth of the small bowel.
 Bacterial overgrowth leads to inefficient intraluminal processing of
dietary fat and to steatorrhea due to bacterial deconjugation of bile
salts, vitamin B12 malabsorption, and microvillus brush border
damage with malabsorption.

20.  Overproduction of d-lactate (the
isomer of l-lactate) can cause stupor,
neurologic dysfunction, and shock
from d-lactic acidosis
 Diagnosis: culturing small bowel
aspirate or by lactulose hydrogen
breath test.
 Treatment: treat the cause of partial
obstruction.
 Initial treatment with 2-4 wk of
metronidazole can provide relief for
many months.
 Cycling of antibiotics including
azithromycin, trimethoprim-
sulfamethoxazole, ciprofloxacin, and
metronidazole is required.
 Occasionally, antifungal therapy is
required to control fungal overgrowth
of the bowel.

21. IMMUNODEFICIENCY DISORDERS
 Malabsorption can occur with congenital immunodeficiency
disorders, and chronic diarrhea with failure to thrive is often the
mode of presentation.
 Malabsorption due to giardiasis or nonspecific enteropathy with
bacterial overgrowth can occur.
 Malabsorption associated with immunodeficiency is exacerbated by
villus atrophy and secondary disaccharidase deficiency.
 In chronic granulomatous disease, phagocytic function is impaired
and granulomas develop throughout the GI tract, mimicking Crohn
disease.
 In addition to failure to thrive, it is important to consider that
malabsorption associated with immunodeficiency is often
complicated by micronutrient deficiencies, including vitamins A, E,
and B12 and calcium, zinc, and iron.

22. MALNUTRITION IN IBD
 IBD is associated with malnutrition due to decreased intake,
malabsorption due to diarrhea and inflammation, chronic steroid use,
results in growth failure and micronutrient deficiencies.
 Optimizing nutritional status and growth are key priorities in the
management of IBD in children and adolescents.
 Energy intake should meet the added costs of catch-up growth and are
usually in the range of 40-70 kcal/kg ideal body weight per day.
 Protein requirements are higher in Crohn disease (1-1.5 g/kg/day).

23. NUTRIENT DEFICIENCIES IN IBD

24. TREATMENT
 Principles: 1. treat the underlying cause
 2. treat the diarrhea
 3. treat associated nutrient deficiencies.
 Loperamide is used to treat diarrhea.
 Avoid beverages with high sugar as soft drinks.
 Nutrition consultation.
 Supplement with iron, folic acid in celiac disease pts.
 Fat-soluble vitamin deficiency: supplement with water soluble forms of Vit A,
D, E, K -5-10 times of RDA.
 Dietary restrictions can help restore normal mucosal function: Gluten-free diet
in celiac disease.
 Elimination of specific Carbohydrates, as in lactose intolerance.
 MCT instead of LCT in diet –steatorrhea, as in short gut syndrome.
 Pancreatic insufficiency: Low fat diet and supplementation with encapsulated
pancrealipase enzyme.
 Each capsule has 30,000IU , 1 with each meal and ½ with snacks. Needs to be
adjusted based on age and weight.

25. REFERENCES
 Kliegman: Nelson Textbook of Pediatrics, 19th edition. Chapter 330:
Disorders of Malabsorption, pages:1305-1322.e3
 Walker-Smith et al, Chronic Diarrhea and Malabsorption (Including
Short Gut Syndrome): Working Group Report of the First World
Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.
Journal of Pediatric Gastroenterology and Nutrition, 35, 2002.
 www.uptodate.com – Clinical features and diagnosis of
malabsorption.
 www.uptodate.com - Overview of treatment of malabsorption.