Iron deficiency workup reveals high incidence of autoimmune gastritis with parietal cell antibody as reliable screening test.

Iron deficiency (ID) workup is a common challenge for gastrointestinal endoscopy. In premenopausal women current guidelines recommend serologic evaluation of coeliac disease only. Here we systematically tested serologic screening for autoimmune gastritis (AIG) in a large cohort of patients with ID. This is a retrospective analysis of patients who attended an out-patient clinic specialized for ID. Patients with ferritin <50 µg/L or transferrin saturation <15% were included. Laboratory workup included endomysial antibodies and parietal-cell antibodies (PCA). Upper gastrointestinal endoscopy with pH-measurement of gastric juice and histology was performed to confirm positive serologic results. Three hundred seventy-three patients with ID were included, about half of whom were anemic. Patients were predominately female with a median age of 40 (confidence interval 11). Positive endomysial antibodies were found in 4 (1%) patients, elevated levels of PCA (>20 U/mL) were found in 69 (18.5%) patients, PCA >100 U/mL in 23 (6.2%). Twenty-six were followed up by gastroscopy; in 12 of 26 patients the diagnosis of AIG was confirmed by histology with 2 additional patients diagnosed as early and/or questionable AIG. A sensitivity of 93% and a specificity of 98% were estimated for a PCA cut-off of 100 U/mL. In 20 patients gastric pH was measured. Achlorhydria was found in 7 patients all diagnosed with AIG. In this ID cohort AIG is by far more common than coeliac disease. PCA above 100 U/mL are a sensitive and specific cut-off for workup of patients with ID prior to endoscopy. Serologic suspicion of AIG helps preselection of patients for endoscopic workup for ID.