NCGS is characterized by gastrointestinal symptoms such as bloating, diarrhoea, weight loss, and abdominal pain. The symptoms can be similar to irritable bowel syndrome (IBS), making it difficult sometimes to differentiate between the two. There can also be extra-intestinal symptoms such as myalgia, bone pain, tiredness, headache, tingling of the extremities, leg or arm numbness and eczema.
Children with NCGS mainly have gastrointestinal symptoms such as abdominal pain, chronic diarrhoea without weight loss. Less frequently, they present with extra-intestinal manifestations, including fatigue and attention-deficit disorders. Currently, it is difficult to know how common this condition is in the paediatric population, but in the adult population, it is thought to be possibly more common than coeliac disease itself.
Symptoms can occur within hours or days of ingesting gluten, and disappear when gluten is removed from the diet.
It is not clear how gluten causes this. Patients do not have positive coeliac serology. They will have negative transglutaminase and deamidated gliadin peptide and endomysial antibodies. Interestingly, they often have positive antigliadin antibodies which are no longer in common use as they lack specificity and sensitivity. (The antigliadin antibodies are different to the newer deamidated gliadin peptide)
Patients also do not have an abnormal small bowel biopsy if this happens to have been done.
It is important that other conditions which can present with similar symptoms be excluded. These include wheat allergy and IBS. Sometimes, the improvement in symptoms when gluten is removed, is actually due to FODMAP foods (fermentable oligo- and disaccharides, monosaccharides and polyols). This group includes a wide range of foods. They include fruit such as apples, pears, watermelon, tinned fruit in their natural juice, lactose containing foods such as milk, cheeses, yoghurt, cereals when consumed in large amounts such as bread, pasta, biscuits, crackers, and vegetables such as asparagus, beetroot, Brussel sprouts, broccoli, cabbage and onions.