Secondary lactose intolerance (secondary lactase deficiency)
Presents as a result of mucosal damage, usually following severe gastroenteritis but also when the epithelium is damaged such as in coeliac disease and cow’s milk allergy
- lactase deficiency may also be a secondary occurrence bowel surgery, cystic fibrosis, or immune disorders. It has also been seen transiently in infants exposed to phototherapy and antibiotic therapy
- usually reversible once the epithelial lining has repaired
- children with suspected lactose intolerance do not usually require any testing and should improve within 48 hours on a low lactose diet
- in secondary lactose intolerance, for example after severe gastroenteritis, lactose can usually be tolerated again by 6 weeks
- if a bout of gastroenteritis or use of antibiotics occurs around the time of the GI symptoms, a secondary lactose deficiency should be suspected. In the intestinal insult that often occurs with secondary lactose intolerance, lactase is the first enzyme to be negatively impacted and the last to recover as the insult resolves
Tests (4)
- Exclusion diet (low lactose) (symptom improvement) and then reintroduction (symptom recurrence). Usually improve within 48 hours of exclusion
Dietary advice (4)
- Low lactose diet - exclude cow’s milk and foods containing cow’s milk, although some with low lactose may be tolerated by some individuals If secondary, should resolve by 6 weeks
Notes:
- symptoms occur only in the bowel - for example, abdominal pain, bloating, flatus, and diarrhoea; lactose intolerance does not cause of rectal bleeding (which may occur in cow's milk allergy) (3,4)
- breastmilk contains lactose (as does any mammalian milk) and decreasing dairy intake in maternal diet does not alter the amount of lactose in breastmilk (5)
- secondary lactose intolerance is temporary, as long as the gut damage can heal. When the cause of the damage to the gut is removed, the gut will heal, even if the baby is still fed breastmilk, or their usual formula (5)
- continuing to breastfeed (or their usual formula) will not cause any harm as long as the baby is otherwise well and growing normally (5)
- lactose intolerance does not cause vomiting or GORD (5)
Reference:
- 1. Host A., Clinical course of cow's milk protein allergy and intolerance. Pediatr Allergy Immunol 1998; 9 (Suppl 11):48-52
- 2. Host A. Cow's milk protein allergy and intolerance in infancy. Pediatr Allergy Immunol 1994;5:5-36.
- 3. Wilson J. Milk Intolerance: Lactose Intolerance and Cow's Milk Protein Allergy. Newborn and Infant Nursing Reviews 2005; 5 (4): 203-207.
- 4. Walsh J et al. Differentiating milk allergy (IgE and non-IgE mediated) from lactose intolerance: understanding the underlying mechanisms and presentations. Br J Gen Pract 2016; DOI: 10.3399/bjgp16X686521
- 5. Wessex Infant Feeding Guidelines and Appropriate Prescribing of Specialist Infant Formulae (Accessed 8/3/2020)