ILLUSTRATIVE CASE
A 43-year-old woman presents to the clinic with diffuse, intermittent abdominal discomfort, bloating, and diarrhea that has slowly but steadily worsened over the past few years to now-daily symptoms. She states her overall health is otherwise good. Her review of systems is pertinent only for 8 lbs of unintentional weight loss over the past year and increased fatigue. She takes no supplements or routine over-the-counter or prescription medications, except for low-dose combination oral contraceptives, and is unaware of any family history of gastrointestinal (GI) diseases. She does not drink or smoke. She is up to date with immunizations and with cervical and breast cancer screening. Her body mass index is 23, her vital signs are within normal limits, and her physical exam is normal except for mild, diffuse abdominal tenderness without any masses, organomegaly, or peritoneal signs.
Her diagnostic work-up includes a complete metabolic panel, magnesium level, complete blood count, thyroid-stimulating hormone measurement, cytomegalovirus IgG and IgM serology, and stool studies for fecal leukocytes, ova and parasites, and fecal fat, in addition to a kidney, ureter, and bladder noncontrast computed tomography scan. All diagnostic testing is negative except for slightly elevated fecal fat, thereby decreasing the likelihood of infection, thyroid disorder, electrolyte abnormalities, or malignancy as a source of her symptoms.
She says that based on her online searches, her symptoms seem consistent with CD—with which you concur. However, she is fearful of an endoscopic procedure and asks if there is any other way to diagnose CD.
CD is an immune-mediated disorder in genetically susceptible people that is triggered by dietary gluten, causing damage to the small intestine.1-6 The estimated worldwide prevalence of CD is approximately 1%, with greater prevalence in females.1-6 A strong genetic predisposition also has been noted: prevalence among first-degree relatives is 10% to 44%.2,3,6 Although CD can be diagnosed at any age, in the United States the mean age at diagnosis is in the fifth decade of life.6
The incidence of CD is on the rise due to true increases in disease incidence and prevalence, increased detection through better diagnostic tools, and increased screening of at-risk populations (eg, first-degree relatives, those with specific human leukocyte antigen variant genotypes, and those with certain chromosomal disorders, such as Down syndrome and Turner syndrome).2-6 However, despite the increasing prevalence of CD, most patients remain undiagnosed.1
The diagnosis of CD in adults is typically made with elevated serum tTG-IgA and endomysial IgA antibodies (EMAs) on initial screening, followed by a duodenal biopsy via EGD for confirmatory testing and/or elucidation of differential diagnoses.7,8 In 2020, guidelines from the European Society for Paediatric Gastroenterology, Hepatology and Nutrition advised that the diagnosis of CD in children can be made without the need for biopsy.9 They stated that serum tTG-IgA antibodies ≥ 10 times the ULN, in conjunction with a positive serum EMA, effectively make the diagnosis without endoscopy. Although the gold standard of EGD with biopsy for diagnosing CD has its own inherent risks and can be expensive, a “no-biopsy” approach has yet to be adopted into guidelines for diagnosing CD in adults.7,8
STUDY SUMMARY
tTG-IgA titers were highly predictive of CD in 3 distinct cohorts
This 2021 hybrid prospective/retrospective study with 3 distinct cohorts aimed to assess the utility of serum tTG-IgA titers compared to traditional EGD with duodenal biopsy for the diagnosis of CD in adult participants (defined as ≥ 16 years of age). A serum tTG-IgA titer ≥ 10 times the ULN was set as the minimal cutoff value, and standardized duodenal biopsy sampling and evaluation for histologic mucosal changes consistent with Marsh 3 lesions was used as the diagnostic reference standard.
Continue to: Cohort 1 was a...
