Usually severe and life threatening. May have been polyhydramnios prior to birth. Abdominal distension, even ileus at presentation, weight loss, nappy rash (if acidic stool).

In some of these conditions, symptoms improve through childhood, but may be susceptible to severe gastroenteritis.

Causes –

• Congenital sodium diarrhoea – metabolic acidosis, low sodium. Can be associated with atresia choanae. Associated with later IBD.
• Congenital chloride diarrhoea – metabolic alkalosis, low chloride. Treat with salt supplementation.
• Congenital sucrase-maltase deficiency – no problem with breast milk, may not present until food aversion/intolerance emerges. Higher rates in Eskimo, where diet traditionally low in carbohydrate!
• Congenital lactase deficiency esp Finland!
• Congenital fructose (cf fructose malabsorption, IBS like) – hypoglycaemia, jaundice. Sucrose also triggers.
• Glucose-Galactose intolerance – high sodium.
• Lysinuric protein intolerance
• Tufting enteropathy
• Microvillous inclusion disease

Some lists include pancreatic disorders eg CF, Schwachmann-Diamond, other causes are abetalipoproteinaemia (so check lipids) and IPEX.

If diarrhoea stops with feed withholding, then osmotic rather than secretory. Anion gap (Na+K-Cl-Bic) in the stool greater than 50 (normal 10-20) indicates unidentified acidic substances.

Reducing substances in stool suggest carbohydrate malabsorption but not reliable (and test no longer made) – bacteria break down complex carbohydrates so false pos, molecular methods better.

Low albumin suggests protein losing enteropathy eg IPEX.

[ Int J Mol Sci. 2012; 13(4): 4168–4185. doi: 10.3390/ijms13044168]