Chronic Diarrhoea

•    Classified by pathophysiological type:

o    Watery: osmotic (e.g. lactose intolerance), secretory (e.g. VIPoma)

o    Fatty (steatorrhoea): malabsorption (e.g. coeliac disease, chronic pancreatitis)

o    Inflammatory: blood/mucus, tenesmus (e.g. IBD, infections)

•    History, stool analysis, and imaging help guide classification

Steatorrhoea

•    Fat malabsorption → pale, greasy, foul-smelling stools that float and are difficult to flush

•    Causes:

o    Coeliac disease

o    Chronic pancreatitis (↓ lipase)

o    Bile acid deficiency (e.g. terminal ileal disease or resection)

o    SIBO

•    Investigation: faecal fat estimation (qualitative or quantitative), faecal elastase (for pancreatic insufficiency)

Micronutrient Deficiencies

•    Iron → microcytic anaemia

o    Absorbed in duodenum; deficiency common in coeliac disease, chronic GI blood loss

•    Vitamin B12/folate → macrocytic anaemia

o    B12 absorbed in terminal ileum (requires intrinsic factor)

o    Folate absorbed in jejunum; rapidly depleted

•    Zinc → periorificial rash, diarrhoea, alopecia, impaired wound healing

•    Other important deficiencies:

o    Vitamin D → osteomalacia, hypocalcaemia

o    Vitamin A → night blindness, xerophthalmia

o    Vitamin K → coagulopathy (prolonged PT)

Refeeding Syndrome

•    Occurs in severely malnourished patients given aggressive nutritional support

•    Sudden ↑ insulin → intracellular shift of phosphate, K⁺, Mg²⁺

•    Features: weakness, arrhythmias, seizures, oedema

•    Prevention:

o    Identify at-risk patients (e.g. BMI <16, prolonged starvation)

o    Replace electrolytes before and during feeding

o    Start nutrition slowly and monitor closely

Total Parenteral Nutrition (TPN)

•    Indicated when enteral feeding is not possible (e.g. short bowel syndrome, bowel obstruction)

•    Complications:

o    Infection (line-related sepsis)

o    Liver dysfunction (cholestasis, steatosis)

o    Electrolyte disturbance

o    Refeeding syndrome

o    Micronutrient imbalances (e.g. trace elements, vitamins)

Feeding Tubes

•    Nasogastric (NG) tube:

o    Short-term use (e.g. <4–6 weeks)

o    Easy to place, less invasive

•    Percutaneous endoscopic gastrostomy (PEG):

o    Long-term feeding (>4–6 weeks)

o    Indicated in neurological dysphagia, head & neck cancers

•    Complications: aspiration, tube dislodgement, site infection