The health visitor has asked you to see an 8-month-old baby girl as she has not been gaining weight recently. Her weight at the age of 6 months was on the 25th centile and it is now on the 2nd. She had an episode of gastroenteritis when she was 26 weeks old. She has recovered but still has loose stools. Her mother says that she has become rather irritable, and is not feeding as well as she used to.
On examination her length is on the 50th centile, as is her head circumference. She looks thin, and her abdomen protrudes somewhat. Otherwise her physical examination is normal.
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(a) What are the possible causes of her poor weight gain?
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The most common reasons for poor weight gain are "psychosocial". However, you need to consider the following in your differential diagnosis:
• lactose intolerance (secondary to her gastroenteritis)
• occult infection, e.g. urinary tract infection
• coeliac disease
• cystic fibrosis
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(b) What might suggest an organic rather than a psychosocial cause?
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This baby has loose stools and a protruding abdomen, which should raise your suspicion that she may have an organic cause. Problems in any organ system can be associated with poor weight gain so she needs a thorough history and physical examination, especially focusing on evidence of chest infections, heart murmur, vomiting, recurrent fever, developmental delay, hepatosplenomegaly and neurological signs.
It is important too to look for non-organic symptoms (rather than consider this as a diagnosis of exclusion). Enquire about eating difficulties, difficulties in the home, limitations in the parents, disturbed attachment between mother and child, and maternal depression or psychiatric disorder. Uncommonly, neglect might be a factor.
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(c) How would you manage this baby?
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This baby has had an episode of gastroenteritis. It is not uncommon for lactose intolerance to develop due to the enzyme lactase being "stripped off" by the inflammation. You could check her stool for low pH and sugar-reducing substances. Alternatively it is acceptable to give her a trial of lactose-free formula. She should begin to gain weight rapidly if she is lactose intolerant.
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(d) What investigations might you consider?
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The combination of loose stools, poor weight gain and irritability around the time of introduction of wheat products suggests coeliac disease and she therefore requires coeliac antibodies to be measured with confirmation by jejunal biopsy. Another important cause of malabsorption, even though she has not experienced chest infections, is cystic fibrosis and a sweat test is also required. Other investigations usually considered include a full blood count, creatinine and electrolytes, fecal elastase, liver function tests and urine for analysis and culture.
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(e) If your investigations come back normal, what would your next step be?
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If investigations were normal you would be more concerned that there might be psychosocial factors. You should discuss this with the mother, and also suggest that the health visitor paid another home visit to observe a meal and see the interaction around feeding and how the baby eats. You could admit her to hospital, but this is often less helpful. Depending on what the issues are, you might involve the GP, refer to a dietitian, suggest placement in a nursery or involve social services.
