Lactose Intolerance

Question 1

Definition of lactose intolerance

Answer 1

A form of malabsorption, where the lactase enzyme is not expressed on the microvilli of the intestine. As a result lactose is not broken down into glucose and galactose. Symptoms of lactose intolerance may overlap with non-IgE mediated cow’s milk protein allergy if there is cow’s milk-induced enteropathy

Question 2

Classification of lactose intolerance

Answer 2

• Congenital lactase deficiency (50% enzyme activity required for normal metabolism)- this is very rare and does not usually manifest before 5 years of age. Is only seen in small populations in Finland and Russia
• Acquired or secondary lactose intolerance- usually transient and may occur with mucosal damage due to underlying GI conditions, following gastroenteritis for example

Question 3

Presentation of lactose intolerance

Answer 3

• May present with abdominal pain, bloating, and explosive diarrhoea typically 30–60 minutes following ingestion of lactose-containing foods
• Stool will be loose and have a foul ‘yeasty’ smell
• Some may also experience nausea and vomiting
• Lactose intolerance should be suspected in all children with acute gastroenteritis who uncommonly have loose stools persisting for more than 2 weeks
• Congenital lactose intolerance should be suspected where there is infantile diarrhoea and failure to thrive
• Where other symptoms are present such as rashes, eczema, rhinitis, vomiting, reflux, constipation and faltering growth, the child is more likely to have cow’s milk allergy

Question 4

Investigations for lactose intolerance

Answer 4

• Diagnosis can be made if the diarrhoea resolves within 2 weeks of exclusion of lactose from the diet
• Lactose intolerance for longer than six to eight weeks is extremely rare in infants and young children and a low lactose formula should not be used for longer than this.
• Hydrogen breath test: detects H2 in breath 3-6 hours after ingestion of lactose
• Jejunal biopsy: rarely needed bt can be used to differentiate from coeliac disease

Question 5

Management of acquired lactose intolerace

Answer 5

• Parents/carers should be advised to give their infant a lactose free infant formula, OR remove lactose from diet under advice of a dietician- may require calcium + vitamin D supplementation
• Intolerance should resolve within 6-8 weeks of gastroenteritis episode- children should be re-challenged with lactose after this (suspect non-IgE mediated Cow’s milk if unsuccessful)
• Mother wo breastfeed should be encouraged to continue and should restrict lactose in their diet
• Refer to support groups such as Allergy UK

Question 6

Management of primary lactose intolerance

Answer 6

o There will be a gradual reduction in the amount of tolerated lactose-containing dairy products- need to discover threshold under advice of a paediatric dietician
o Can give low lactose products and calcium/ vitamin D supplementation