Serology an increasingly important indicator of celiac disease

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - 9/1/2019

Serology has gained importance in the diagnosis of celiac disease (CD), due to improvements in assay performance over the last decade, according to updated advice for clinical practice.

"This expert review addresses advances in the detection and diagnosis of celiac disease. It is clear that blood tests have become an indispensable and usually initial test to detect celiac disease," co-author Dr. Joseph A. Murray of Mayo Clinic in Rochester, Minnesota, told Reuters Health by email.

CD diagnosis relies on symptom recognition, serology and histological analysis of duodenal biopsies, Dr. Murray and colleagues write note in their Best Practice Advice report in Gastroenterology, online December 19.

"In children and adolescents, repeated serological testing with high TG2-IgA levels may render a gastroscopy with biopsy unnecessary. Cases with IgA-deficiency deserve special recognition. Treatment consists foremost of a GFD (gluten-free diet)," they explain. "It is important not to initiate a GFD before measurement of antibodies and biopsy. Follow-up secures the avoidance of long-term side effects of the GFD and aids the adherence to the GFD. The utility of serology vs. histology in follow-up has not been definitively settled."

The researchers reviewed published evidence, including cohort and case-control studies of CD diagnosis and controlled and descriptive studies of CD management.

Their recommendations highlight the following points:

  • Serology, especially tissue transglutaminase-IgA (TG2-IgA), IgA testing, and endomysial IgA testing, is an important tool to help diagnose celiac disease. TG2-IgA level higher than ten times the upper normal limit is an accurate and reliable indicator of active CD.
  • Testing of duodenal biopsies according to the Marsh classification, counting lymphocytes per high-power field, and cell shape all help providers determine whether their patients have celiac disease.
  • Before they begin a gluten-free diet, patients diagnosed with celiac disease by intestinal biopsies should undergo celiac-specific serology to confirm that they actually have CD.
  • Individuals who have already begun a gluten-free diet before being diagnosed with CD are advised to go back on a normal diet with three slices of wheat bread daily for one to three months if possible, then have their TG2-IgA retested.
  • Persistent positive serology is usually a sign of ongoing intestinal damage and gluten exposure, the authors explain. But in people who have continued intestinal injury and are being treated for it, negative serology does not necessarily mean that the intestinal mucosa has healed. These patients need to undergo follow-up serology six and 12 months after diagnosis, then every year.
  • Patients with persistent or relapsing symptoms that can't easily be explained should undergo endoscopic biopsies to evaluate healing despite negative TG2-IgA.

SOURCE: https://bit.ly/2FiS0Xj Gastroenterology 2018.

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