Genetic tests can confirm celiac disease diagnosis
This week’s Your Child’s Health was written by Dr. Pankaj Vohra, a pediatric Gastroenterologist at the University of New Mexico Hospital. He is available for questions or comments at pvohra@salud.unm.edu.
Q: Our family practitioner tells me that my 12-year-old grandson may have celiac disease as he is having recurrent diarrhea. Can you please tell me more about this condition and what do I have to do about it?
A: Celiac disease is a permanent intolerance to gluten. Gluten is a protein found in wheat, rye and barely. Some celiac disease patients also do not tolerate the gluten found in oats. This disease is becoming more common. It affects anywhere from 0.7-1 percent of the population.
There is a genetic basis to the disease, i.e. almost 99 percent of the patients diagnosed with celiac disease have one or the other gene — HLA DQ2 or HLA D. However, the disease can present at any age — in children or adults. They just need to be consuming gluten in some form or the other. Unfortunately, we don’t know yet what the trigger could be that initiates the disease. However, keep in mind that almost 30%-40% of the population has one of these genes, but only a small percentage of them go on to develop the disease. Looking at it another way, if the gene is absent, then it is very unlikely that you have or will develop celiac disease. This means that the mere presence of the gene does not confirm that you have celiac
disease.
Celiac disease can present in many ways. Children often present with gastrointestinal symptoms just like your grandson. These could include non-bloody diarrhea, abdominal pain, bloating, weight loss, vomiting and sometimes constipation. A smaller percentage of children present with symptoms outside the intestinal tract, including anemia, liver disease, headaches, bone loss resulting in frequent fractures, itchy skin rash, short stature, delayed puberty or an association with another autoimmune disease like hypothyroidism or insulin-dependent diabetes. In fact, celiac disease should be considered in almost any non-febrile chronic condition that does not have a specific cause or is not responding to standard therapy.
Diagnosis of celiac disease is easy once you think about it. A blood test is a screening test and the most commonly used one is called Tissue Transglutaminase IgA antibody (tTG IgA). This is the test I am assuming your grandson had and which came back positive. A negative tTG antibody in the presence of sufficient Immunoglobulin A levels (these 2 tests are often done together) makes the likelihood of celiac disease very low (except in the children under 2 years old), but a positive result may or may not mean definite celiac disease.
As the disease is lifelong, and requires a special and strict diet, the standard recommendation is to get an upper gastrointestinal endoscopy with duodenal biopsy. This test is an outpatient procedure, is safe for children, and in children is performed under anesthesia. The duodenum is the scientific name given to the bowel that is attached to the stomach and bears the brunt of celiac disease. A small bit of tissue from here is checked under the microscope and that clinches the diagnosis.
Once the diagnosis of celiac disease is made based on the biopsy, we need to plan treatment, which means the patient must go on a complete gluten-free diet (GFD). GFD must be lifelong and has to be 100 percent, with no exceptions. There are plenty of gluten-free food options and many products available that allow you to cook a healthy, balanced GFD at home. GFD options are available in schools and colleges, as well.
Initially, some patients when diagnosed will be anemic, with vitamin and mineral deficiencies, and should be supplemented for the initial few months. With a strict GFD, the patient shows improvement within weeks and the tTG antibody level slowly starts to reduce and becomes negative within two years of diagnosis. Children who follow a strict GFD enjoy a wonderful quality of life. Their growth, mental and physical development, and capacity is second to none.
Finally, three further points to consider:
Don’t start a GFD before confirmation of the diagnosis.
Once diagnosed, celiac disease or another autoimmune disease may be present in the child or the immediate relatives, and hence should be looked for.
An annual visit to the gastroenterologist is recommended.