Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (949 page)

   Monitoring response to dietary therapy

   When TTG-IgA is normal in patients with villous atrophy

   Patients with a high pretest probability of celiac disease but a negative TTG- IgA: guiding a decision regarding the need for endoscopy and biopsy

   Interpretation

Increased In

   Celiac disease

   Dermatitis herpetiformis

   Limitations

   Biopsy of the proximal small intestine is indicated to confirm the diagnosis of celiac disease in a patient with positive serologic test(s) for antibodies to TTG or deamidated gliadin. It is recommended that multiple tissue specimens be taken at biopsy to avoid false-negative histology in patients with focal disease.

   The levels of antibodies to TTG and deamidated gliadin peptides decline slowly in patients treated with a gluten-free diet, and serologic testing may be repeated to assess the response to treatment. In a typical patient, it may take up to 1 year for results to normalize. Persistently elevated results suggest poor adherence to the gluten-free diet.

GLUCAGON

   Definition

   Polypeptide hormone secreted by the islet alpha cells in the pancreas. Stimulates the production of glucose in the liver and the oxidation of fatty acids

   
Normal range
(by age):

   Newborn (1–3 days): 0–1,750 pg/mL