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Lactose intolerance is a common causes of diarrhea, resulting from a deficiency in the enzyme lactase.
Primary lactose intolerance is seen in older children and adults, primarily of East Asian or African descent. LI has a prevalence of 80-90% in Chinese
Secondary lactose intolerance is transient and follows persisent diarrhea, ie post-infection, with celiac disease, or IBD.
A history of increased symptoms with lactose containing-foods - milk, cheese, etc is common. However, milk products may be found in unexpected sources.
A trial of lactose-free diet can be helpful.
Children show no failure to thrive.
Positive hydrogen breath test in children >6
stool shows acid pH and is positive for reducing sugars
Other causes of chronic diarrhea should be considered.
A lactose-free diet is recommended. Soy forumlas can be given to infants.
Lactase-containing pills or milk is available.
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