Celiac disease (CD) is diagnosed by evaluating symptoms, reviewing family and medical history, conducting blood tests and a small intestinal endoscopy (biopsy).

People with CD can have many different symptoms or no symptoms at all, up to 200 symptoms are associated with CD, here are some of the most common ones:

Gastrointestinal

• Diarrhea
• Fatty stools
• Constipation
• Cramps
• Bloating
• Flatulence
• Lactose intolerance
• Acid reflux
• Nausea
• Vomiting

Malabsorption- related

• Anemia-Iron deficiency
• Vitamin deficiencies
• Calcium malabsorption leading to osteopenia, osteoporosis
• Protein and calorie malnutrition
• Weight loss or muscle atrophy
• Poor growth in children
• Failure to thrive

Non-Gastrointestinal

• Fatigue
• Depression
• Joint pain
• Muscle aches, cramps
• Peripheral neuropathies
• Infertility
• Menstrual irregularities
• Dental abnormalities
• Brain Fog

Blood tests: Blood is tested for celiac-specific antibodies (referred to as a celiac panel). These antibodies are proteins in the blood that are produced in response to gluten ingestion.

Here are some of the most common blood tests:

• tTG IgA (anti-tissue transglutaminase antibody)
• Total IgA (if deficient alternate testing may be needed)
• EMA (anti-endomysial antibody)

Endoscopy: The next step is an endoscopy of the small intestine, also called a biopsy – this is a test to check for inflammation and damaged villi. This is considered the “gold standard” for diagnosing CD. During an endoscopy, a scope with a small camera at the end is passed down the mouth, esophagus, stomach and into the small intestine. The doctor will look for damage and inflammation and several samples are taken of the intestinal lining. ¹

NOTE: Starting a GF diet before diagnosis may lead to a false negative test, therefore it is important to keep eating a gluten-containing diet through the diagnostic procedures.

You can also do genetic testing for celiac associated genes, but genetic testing will ONLY rule out CD, and cannot be used as a diagnostic test, less than 5% of those with the celiac-related genes will develop CD.  The names of the genes are HLA DQ2 and HLA DQ8.

 You can read more about genetic testing in these two answers by Melinda Dennis:

https://nationalceliac.org/celiac-disease-questions/ancestry-type-testing-for-celiac-genes/

https://nationalceliac.org/blog/celiac-genes/

Check out this infographic that explains the different celiac-related tests.

Reference:

1. National Celiac Association. Gluten-Free, Off to A Fresh Start. Presentation. May 4, 2018.

Reviewed and updated October 20, 2022.