Aims Cow’s milk protein intolerance (CMPI) is common in infancy, with a prevalence rate of approximately 2%–3% in the UK. The average of age diagnosis of CMPI is 3.5 months in typically developing infants. The clinical symptoms suggestive of CMPI are gastroesphageal reflux, change in bowel pattern, faltering growth, irritability, eczema and respiratory symptoms. These clinical symptoms are commonly present in infants with Down syndrome. In this study we wanted to determine the prevalence of CMPI in children with Down syndrome and if there was delay in diagnosis due to diagnostic overshadowing.

Methods One hundred and forty-eight children (0–19 years) were identified with Down syndrome, thirty-six children were under the five years. All 36 case notes of children under the age of five years were audited using the NICE (2015) guidance for CMPI.

Results 30/36 children (83.3%) had one or more symptoms (respiratory, gastrointestinal, skin, feeding difficulties and faltering growth) that could have been related to CMPI (table 1). 8/36 children (22.2%) were treated for CMPI. Mean age at diagnosis was 4.6 months and average symptoms per child was 2.8 with gastrointestinal symptoms present in 100% and feeding difficulties in 87.5% of children with CMPI. No children were identified as having IgE mediated CMPI. All eight children were initiated on a cow’s milk protein free diet, with an improvement of symptoms.

Conclusion In our study shows that in children with Down syndrome there is an increased prevalence of non-IgE mediated CMPI and there is a potential delay in diagnosis. We recommend that CMPI should be considered all infants with Down syndrome who have difficult to manage gastroesphageal reflux and more than one system involvement and consider using CoMiSS scoring, to prevent diagnostic overshadowing and prompt management according to current CMPI guidance.