Lactose intolerance

Question 1

Define malaborption

Answer 1

Manifestations of malabsorption:

1. Abnormal stools: True malabsorption stool is difficult to flush and has a potent smell
   NOTE: colour is not a good gauge of abnormality
2. Poor weight gain or faltering growth in most but not all cases
3. Specific nutrient deficiencies, either singly or combined

Some disorders affecting the small intestine mucosa and pancreas e.g. chronic pancreatic insufficiency => may lead to malabsorption of many nutrients (pan-malabsorption)

Other disorders can be highly specific e.g. zinc malabsorption in acrodermatitis enteropathica

DEFINITION of acrodermatitis enteropathica: autosomal recessive metabolic disorder characterised by malabsorption of zinc which results in:
1. Diarrhoea
2. Inflammatory rash around the mouth and/ or anus
3. Hair loss

Question 2

Define lactose intolerance

Answer 2

The development of gastrointestinal and/or systemic symptoms secondary to malabsorption of lactose caused by hypolactasia

Lactase deficiency (lactose → glucose and galactose) à lactose ferments in gut à ↑ waste gas à pain and bloating

o RFs: FHx, ethnicity

o Affects up to 75% of world’s population (less Caucasian, more Asian, African and Hispanic)

Question 3

Aetiology

Answer 3

Reduced lactase enzyme concentration in the microvilli of the small intestine, usually at the age of weaning

• Lactase deficiency -> lactose ferments in gut => waste gas => pain and bloating
• Affects up to 75% of world’s population (less Caucasian, more Asian, African and Hispanic)
• Comorbid predisposes diseases include: HIV enteropathy, CF, diabetic gastropathy, Kwashiorkor, Zollinger-Ellison syndrome, Whipple’s disease

Primary (70%) / AR → deficient lactase (Asian, African, Hispanics)

Secondary (30%) → damage to gut, temporary lactase deficiency (gastroenteritis, Crohn’s, coeliac, alcoholism)

o I.E. previous bout of gastroenteritis and full resolution with persistent diarrhoea from temporary damage

o Exclude: gastroenteritis (stool sample), Crohn’s (faecal calprotectin, colonoscopy) Coeliac’s (anti-tTG/EMA)

Question 4

Clinical presentation

Answer 4

• Diarrhoea
• Distension
• Lethargy
• Failure to thrive
• Abdominal pain/ discomfort
• Flatulence
• Mouth ulceration
• Headache
• Eczema, skin rashes
• Muscle and joint pain

Question 5

Investigations

Answer 5

1. Abdominal examination/ observations
2. Food diary
3. Clinical diagnosis (trial lactose-free diet for 2 weeks and see how symptoms are)
4. . Breath hydrogen test:
   Lactose hydrogen breath test- given lactose solution and measure hydrogen levels (if high levels after drinking solution, then lactose intolerant)

• Normal = unabsorbed CHO fermented by large intestine GIT bacteria to produce H2 which is absorbed by the blood and exhaled from the lungs a period of time after initial ingestion
• Pathology = GIT bacteria extend to small intestine from large intestine (due to overgrowth) and CHO metabolism occurs earlier in digestion leading to an earlier rise in exhaled H2 following CHO ingestion

.5. Lactose intolerance test (outdated):
* Lactose tolerance test- drink lactose solution and measure blood glucose (no rise/ slow rise = intolerant) - outdates

.6. FBC (rule out secondary disease => anaemia, ↑WCC)

Question 6

Management

Answer 6

Dietician referral

1. Avoid milk and dairy products => provide calcium and vitamin-D supplementation
   NOTE: soya formula is NOT recommended for children < 6 months as it may interfere with sexual and physical development

For primary LD:

1. Experiment with diet – different with each child, need to discover individual lactose threshold
2. Potential foods:
   High-fat dairy (lower lactose)
   Hard cheeses
   Milk substitutes (almond, soya, coconut)

For secondary LD:
* Cut out dairy and allow gut time to heal
* May need Ca2+ and Vitamin D supplements
* Digestive enzymes can be taken in a capsule before eating lactose until gut heals/matures

Question 7

Complications

Answer 7

Complications
* Osteoporosis
* Rickets
* Malnutrition
* Failure to thrive
* Growth failure

Prognosis
* Excellent with lactase reduction
* Persistent symptoms are either due to ongoing inadvertent lactose exposure, IBS or poorly controlled underlying disorders of secondary lactase deficiency
* Treatment is LIFELONG
* Adherence may be a problem