Week3: malabsorption Flashcards
Signs of malabsorption
-malodorous stools
-chronic diarrhea
-failure to thrive
-weight loss
-subnormal growth
SEVERE
-edema
-rickets
-potbelly
-decreased muscle mass
-decreased fat stores
-excessive bruising or bleeding
Failure to thrive and workup
-need to categorize whether failure to thrive is due to deficient diet, malabsorption, or abnormal energy utilization
Workup
1. history: dietary intake, family environment, developmental milestones
2. physical exam
-height, weight, head circumference
-findings: anemia, short stature, fat stores, rash, joint swelling, goiter, organomegaly
Nutrient absorption
- mostly in the proximal small intestines
- B12 and bile acids in the terminal ileum
Causes of defects in fat, carb, and protein digestion
- Fat -defective intraluminal phase of digestion
- pancreatic insufficiency due to CF
- hepatobiliary dysfunction associated with biliary atresia and primary biliary cirrhosis - Carbs- usually defective mucosal phase
- secondary to excess intake, mucosal damage, short bowel syndrome, congenital intestinal trasport/enzyme deficiencies - Proteins
- hypoproteinemia more likely due to deficient dietary intake and excessive intestinal protein loss *protein losing enteropathy
- celiac, crohn’s, elevated fecal alpha-1-antitrypsin
Secretory diarrhea-malabsorption
- can result in malabsorption if severe
- seen in infections, short bowel syndrome, severe GI mucosal injury, secretory tumors
- electrolyte content of stool approaches serum
Causes of malabsorption
- pancreatic disorders
- chronic cholestasis
- GI surface injury
- celiac, crohn’s, short bowel syndrome, infectious and post infectious diarrhea, congenital intestinal enterocyte brush border enzyme deficiencies, bacterial overgrowth - abnormal lymphatic drainage
GI presentation in CF
- inspissated (thickening by dehydration) plugging by proteinaceous secretions in pancreas
- bulkly loose stools in infants, cholestasis, pancreatitis
- 20% of CF patients have meconium ileum -thickened and congested meconium in ileum
- constipation
- Tests of pancreatic sufficiency: stool trypsin (if present, it is good)
rare causes of pancreatic insufficiency
- shwachman diamond syndrome
- autosomal recessive disorder,
- lipomatosis of pancreas with congenital pancreatic insufficiency
- short stature, skeletal abnormalities - Johanson-blizzard syndrome
- fatty replacement of pancreas
- GI anomalies: imperorate anus
- birdbeak nose, deafness, hypothyroidism
Chronic cholestasis
- any hepatobiliary disorder that results in chronic cholestasis can cause fat malabsorption
- can have fat-soluble vitamin deficiencies
- Vit E def. -ataxia, hyporeflexia, ocular palsy, hemolytic anemia
- Vit K: reduced coag factors
- Vit D: rickets, osteopenia
- VIt A: night blindness
- Presentation: jaundice since infancy
- children in early infancy have biliary atresia
- Alagille syndrome: cholestasis, congenital heart disease, short stature, characteristic facies, skeletal/rib abnormalities
Causes of malabsorption due to GI mucosal surface injury
- Celiac disease
2. Crohn’s disease
Infectious diarrhea causing malabsorption
- Giardia -non bloody diarrhea
- Cryptosporidium -watery and non bloody diarrhea. affects immunocompromised
- post-infectious diarrhea
- sustained acute diarrheal illness
- lactose malabsorption can occur in patients with repetitive diarrhea, previous GI disease, live in developing country
- intractable diarrhea of infancy: longer than 2-3 weeks - Rotavirus: injury of brush border by toxin. early childhood.
Congenital intestinal enterocyte brush border enzymes deficiency
- presentation: watery diarrhea, bloating, abdominal distension, acidosis, dehydration after birth
- rare diseases
- stools test positive for acid and reducing substances
- hydrogen breath test
- lactose intolerance: nonresistance of lactase after childhood is normal. Secondary intolerance is common, loss of lactase secondary to other diseases. Congenital is rare.
Primary intestinal lymphangiectasia
- findings of malabsorption of long chain fatty acids, low fat soluble vitamin levels, lymphopenia, abnormal lymphatic imaging studies
- there is abnormal draining of lymphatics.
- short and medium chain fatty acids can be absorbed and transported directly through mesenteric venous blood to liver
secondary intestinal lymphangiectasia
-results as a consequence of many disorders, e.g. Crohn’s, mycobacterial infections, radiation enteritis, lymphatic turbos, other neoplasms, heart disease
Screening tests for Malabsorption
Blood -Celiac panel with IgA level -CF DNA mutations in CFTR -fat soluble vitamin levels -other vitamin levels Stool -FA1AT for PLE- celiac, crohns -trypsin -stain for fat -24 hour fecal fat -pH -Clinitest: tests for reducing substances in urine. (lactose malabsorption, or other sugars) Other -sweat chloride test for CF -Hydrogen breath test for carb malabsorption
