How is Celiac Disease Tested?
What is Celiac Disease and How Does it Develop?
Celiac disease is the most common autoimmune small intestine disease affecting 1-2% of individuals in most populations of Caucasian ancestry (these include Europe, North and South America, the Arab region, India, Pakistan, and possibly northern China), and it is also the most frequent cause of chronic diarrhea. Celiac disease typically affects the small intestine and is a condition where there is a permanent intolerance to gluten, leading to deterioration of health. However, a systemic presentation of the disease is now seen in about half of patients. It is an example of a multifactorial disease involving genetic, environmental, and immunological factors. While some genetic factors are not sufficient for disease development, their presence is absolutely necessary. These necessary factors are HLA allotypes. The allotype most strongly associated with celiac disease is a variant of HLA-DQ2, called HLA-DQ2.5, found in 90-95% of people with celiac disease. Homozygosity for DQ2 is associated with early-onset and classic celiac disease. The remaining patients carry HLA-DQ8, called DQ2.2, or another HLA-DQ2 variant. Gluten is a significant environmental factor that triggers the development of celiac disease. The term gluten, which causes a range of effects in cell culture systems, refers to a mixture of gliadin and glutenin proteins derived from grains such as wheat, barley, and rye. It is a lifelong disease.
What are the Common Clinical Manifestations of Celiac Disease?
In children, it presents as diarrhea, growth and developmental delay, short stature, abdominal distension, and abdominal pain. In adults, common symptoms include iron deficiency anemia and diarrhea.
How is Celiac Disease Diagnosed?
Diagnosis is made by the presence of classic symptoms, response to a gluten-free diet, the onset of classic symptoms upon exposure to gluten compared to its absence, and positive serological findings.
How is Celiac Disease Tested?
Celiac disease is tested using serological tests (blood tests). Endoscopic biopsy may also be performed to confirm the diagnosis and monitor the course of the disease. The serological tests performed are as follows: IgA tTG (tissue transglutaminase antibody): This is the first-step test used for screening for celiac disease. IgG DGP (deamidated gliadin peptide): This is the first-step test used for screening for celiac disease in patients with IgA deficiency. IgA EMA (endomyseal antibody): This is the second-step test used to confirm celiac disease. IgG tTG (tissue transglutaminase antibody): This is not recommended for routine use due to its lower sensitivity compared to IgG DGP. IgA DGP (deamidated gliadin peptide): This is not recommended for routine use due to its lower sensitivity compared to IgA tTG and IgA EMA.
Who Should Be Screened for Celiac Disease?
Patients with any unexplained chronic diarrhea, patients with malabsorption syndromes (digestive and absorption disorders), individuals with unexplained vitamin and mineral deficiencies, patients with anemia (folic acid, iron deficiency), patients with osteoporosis, individuals with unexplained transaminase elevations, first-degree relatives of celiac patients, those with autoimmune diseases such as type 1 diabetes, primary biliary cirrhosis, Sjögren's syndrome, individuals with Down syndrome and Turner syndrome, individuals with unexplained neurological conditions such as peripheral neuropathy, epilepsy, and ataxia, should be screened for celiac disease.
