Definition: reduction in gut function to below the minimum necessary for both adequate absorption of macronutrients and/or water and electrolytes. 

Classification:

Type 1 IF: 

• common, acute onset, usually self limiting condition 
• few long term sequelae
• following abdominal surgery or in the context of critical illness. 
• IV fluid and  electrolyte support may be required for a few days to weeks. 

Type 2 IF: 

• far less common, 
• following an acute intra abdominal event (ischaemia, volvulus, trauma or perioperative complication) often with septic and metabolic problems, creating complex  nutritional issues, requiring support for weeks to months with  multidisciplinary input 

Type 3 IF: 

• chronic condition in which patients are metabolically stable but require full intravenous nutrition support over months to years. It may or may not be reversible. 

Causes of Intestinal Failure:

• Short bowel syndrome
• Chronic intestinal dysmotility 
• Chronic intestinal pseudo-obstruction 

Complication:

• Protein energy malnutrition, weight loss, 
• Diarrhea → dehydration, Na & Mg depletion, ARF
• The absence of the ileum leads to → 
  • Deficiencies of vitamin B12 and fat soluble vitamins. 
  • Decreased absorption of drugs: thyroxine, digoxin and warfarin.
  • Gallstones, calcium oxalate renal stones 

Mechanism of gall stone, renal stone formation in ileal disease or ileal resection