Testing for coeliac disease is most accurate when a person is still consuming gluten. Starting a gluten free diet before testing can cause falsely negative and unreliable results. If gluten has been removed from the diet for a number of months, a gluten challenge will be required to allow for a conclusive diagnosis.
A HLA gene test, if negative, can be used to exclude a diagnosis of coeliac disease.
A positive HLA gene test result is not diagnostic and a gluten challenge followed by testing will still be required to establishthe diagnosis.
The following options can be discussed with your patient:
Option 1
Recommend a gluten challenge. One option is to recommend 8-10g gluten per day (for adults) for 6 weeks prior to testing. This is equivalent to approximately 4 slices of wheat-based bread per day. Our fact sheet, Gluten Challenge, has more information.
Option 2
If your patient is reluctant or unable to complete a gluten challenge, offer HLA-DQ2/8 gene testing. If HLA DQ2/8 gene testing is negative, coeliac disease can be safely excluded. If it is positive, then option 1 is the only feasible diagnostic approach.
Gluten challenge is discouraged in children under the age of 5 years and during the pubertal growth spurt because of potential negative effects on growth.
