Congenital Diarrhoea
Ix
Serum electrolytes, osmolarity
Stool electrolytes, osmolarity, pH, reducing substances
Trial of fasting (secretory continues, osmotic stops)
Mucosal biopsy
stool osmo >40mOsmo higher than serum = osmotic
steatorrhoea: greasy
Stool reducing substances pick up all monosaccarides (gluc/galac/fruct), lactose, maltose but not sucrose)
if neg if sucrase deficiency
Congenital secretory diarrheas (often mistaken for urine)
- Congenital chloride diarrhoea (histo normal)
- SLC26A3 (solute-linked carrier family 26 member A3) gene, encodes an epithelial anion exchanger
- hyponatraemia, hypochloremia, and metabolic alkalosis (unlike the metabolic acidosis present in most chronic diarrheas); there may be a history of polyhydramnios
- Urine Cl > cations ?CCD (not as sensitive it not in balance ie chronic as hypochloraemic Rx Cl
- Congenital sodium diarrhoea (histo normal)
- Hyponatraemia, met acidosis,
- if SPINT2 gene mutations, comes with choanal or anal atresia
- Microvillus inclusion disease (histo: villous atrophy and inclusion bodies)
- Tufting enteropathy (histo: villous atrophy with focal crowding and tufts)
- can have ophthalmological assiciations: superficial punctate keratitis, conjunctival erosions
Rx ? TPN / intestinal transplant
Congenital osmotic (malabsorptive) diarrheas
- Glucose-galactose malabsorption (normal histo)
- deficiency in the intestinal sodium/glucose transporter, encoded by the solute carrier family 5, member 1 gene (SLC5A1)
- ceased with fasting or cessation of lactose and its two monosaccarides: glucose and galactose.
- Hydrogen breath test confirms (with normal biopsy)
- Rx fructose formula, lifelong exclusion of above 3 sugars
- Congenital sucrase-isomaltase deficiency
- Inuits are the main population
- asymptomatic while exclusively breastfeed
- symptomatic once sucrose formula/food commenced
- cant hydrolyse sucrose, maltose, starch
- Enteric anendocrinosis (histo absence of enteroendocrine cells)
- mutations in neurogenin-3 (NEUROG3) causing paucity of enteroendocrine cells in the pancreas and intestine
- initial osmotic diarrhoea, later insulin depended DM without islet antibodies
Maldigestion of fat
= steatorrhoea, FTT, fat soluble vitamin deficiencies
Pancreatic enzyme deficiency
- Cystic fibrosis
- Shwachman-Diamond syndrome (marrow failure and skeletal anomalies)
- Pancreatic lipase deficiency
- Abetalipoproteinemia: cant form chylomicrons
- Primary bile acid malabsorption
- Chylomicron retention disease (enterocyte distended with lipids, can cause secondary carb/protein malabs)
- Diacylglycerol acyltransferase 1 deficiency