Malabsorption in a child (lactose intolerance, coeliac disease) Flashcards
What is a food intolerance vs food allergy?
Food intolerance - non-immunological hypersensitivity reaction to a specific food
Food allergy - pathological immune response (usually IgE mediated) against a specific food protein
What is the cause of most milk intolerance in children?
Allergy to cow’s milk protein and NOT lactase deficiency
What are 2 causes of lactose intolerance?
Primary lactase deficiency - this is the enzyme which converts lactose into monosaccharides, glucose and galactose and is present at the tips of the villi in small intestine
Postgastroenteritis intolerance - may start with vomiting and diarrhoeal illness and vomiting stops but watery stools may continue for several weeks
How does lactose intolerance incidence vary with age?
Ability to digest lactose is gradually lost from time of weaning onwards in most populations.
Premature infants may have developmental lactase deficiency which improved as the intestine matures
What is the epidemiology of lactose intolerance?
Prevalence is:
- 5-17% in Northern Europe
- 70-95% in Africa and Asia.
Individuals in countries where diet tends to include more dairy products (such as the UK) are more likely to inherit a retained ability to digest lactose and not experience symptoms.
What are the clinical features of lactose intolerance? What is the pathophysiology of these symptoms?
Bloating, flatulence and abdomial discomfort - reduced lactose absorption means it is instead broken down by bacterial producing gas and short-chain fatty acids
Loose water stools +/- urgency and perianal itching due to acidic stools - due to acidic and osmotic effects of undigested lactose
Malnutrition and failure to thrive is uncommon.
How can you diagnose lactose intolerance?
Lactose-free diet trial for 2 weeks - careful attention to labels. If symptoms resolve then recur on re-introduction then diagnosis can be made
Breath hydrogen test - in lactose intolerance bacterial overgrowth may occur in small intestine causing lactose to be fermented and hydrogen gas to be produced, absorbed into blood and excreted by lungs much earlier than would occur in large intestine. A rise in exhaled hydrogen concentration is therefore measured.
What formula is used in infants with lactose intolerance?
Specialised formula - the usual lactose which is the carbohydrate present in cow’s milk is hydrolysed or protein can also be derived from amino acids or soya.
What is the management of lactose intolerance? What are the complications?
Management: avoid milk and dairy products (although varying amounts may be tolerated depending on individual), lactase enzyme preparations are available in health shops but evidence of efficacy is variable
Complications: dehydration from chronic diarrhoea, avoiding milk may cause calcium deficiency especially in children (may cause faltering growth)
Prognosis: may recover spontaneously if intolerance caused by severe gastroenteritis.
Does breast milk contain lactose? Sholuld mothers stop breastfeeding in lactose intolerance?
Breastfeeding is the best form of nutrition for every child
Breastmilk contains lactose but also components which aid lactose absorption - mothers who are breastfeeding should continue doing so
Babies who are formula fed should be switched to a lactose free infant formula.
This 2-year-old boy had a history of poor growth from 12 months of age. His parents had noticed that he tended to be irritable and grumpy and had three or four foul-smelling stools a day. A duodenal biopsy at 2 years of age showed subtotal villous atrophy. What is the most likely diagnosis?
Coeliac disease - he was started on a gluten-free diet. Within a few days, his parents commented that his mood had improved and within a month he was a ‘different child’. He subsequently exhibited good catch-up growth.
Histology showsn lymphocytic infiltration and villous atrophy confirming coeliac disease
What features of Coeliac disease are seen on this 2 year old boy?
Wasting of the buttocks and distended abdomen
Define coeliac disease.
Gluten-sensitive enteropathy
How and when does coeliac disease usually present?
Presents at 8-24 months
- Abnormal stools
- Faltering growth
- Abdominal distension
- Muscle wasting
- Irritability (now rare)
Subtle signs (more common presentation now)- short stature, anaemia (iron and folate deficiency, B12 deficiency), persistent mouth ulcers, abdominal pain or can present during screening in increased risk (e.g. DM, AI thyroid disease, Down syndrome).
What is the pathophysiology of coeliac disease?
Gliadin found in gluten and other prolamines of wheat, barley and rye cause a damaging immunological response in the proximal small intestinal mucosa
This causes an increased rate of migration of absorptive cells in the villi (enterocytes) from crypts which is still insufficient to compensate for increased cell loss from villous tips
Villi become progressively shorter and then absent leaving a flat mucosa
Is there a genetic component to coeliac disease?
10-15% first-degree relatives will also be affected
Identical twin concordance is 70%
HLA-DQ2 and 8 association
How common is coeliac disease?
Affects 1% of the population
Age of presentation is partly influenced by age of introduction of gluten into diet
What investigations are used to diagnose coeliac disease?
Small bowel biopsy: provides definitive diagnosis as presence of antibodies may still cause asymptomatic disease. Shows mucosal changes (increased intraepithelial lymphocytes and a variable degree of villous atrophy and crypt hypertrophy)
Positive serology: total immunoglobulin A (IgA), IgA anti-tTG and IgA EMA (endomysial antibodies). Should be x10 upper limit of normal.
NB: there is no place for the empirical use of a gluten free diet as a diagnostic test. FBC and LFTs may show abnormalities.
Which products must be removed from the diet as part of coeliac disease management?
Wheat
Rye
Barley
Describe the overall management of coeliac disease in children.
Referall to paediatrician - for further investigations
Dietician support - removal of all products containing wheat, rye and barley for life
If the initial diagnosis is doubtful then a gluten challenge may be required later in childhood to demonstrate continuing susceptibility of small intestine mucosa to damage by gluten
What are the complications of non-adherence to a gluten free diet in coeliac disease?
Development of micronutrient deficiency including osteopenia
Small risk of bowel malignancy, especially small bowel lymphoma
