Gastrin improves pernicious anaemia diagnosis in absence of intrinsic factor antibodies

Serum gastrin levels enhance the noninvasive diagnosis of pernicious anaemia and lessen the need for endoscopy in B12-deficient patients with isolated anti-parietal cell antibodies (APCA), reports a study.

Eighty-six patients with B12 deficiency were prospectively enrolled and categorized into the following groups: confirmed pernicious anaemia with intrinsic factor antibodies (IFA group), suspected pernicious anaemia with APCA only (APCA group), and nonpernicious anaemia controls with chronic proton pump inhibitor (PPI) use (PPI group).

The authors evaluated serum gastrin, chromogranin A, pepsinogen I and II, and ghrelin. They also stratified analyses by PPI use.

Both gastrin and chromogranin A strongly correlated with pernicious anaemia among APCA patients, with gastrin being the most informative biomarker and showing an independent association with pernicious anaemia.

Notably, the use of PPIs had a significant impact on gastric levels, supporting stratified thresholds. The diagnostic accuracy of gastric was excellent (AUC 0.98 without PPI, 0.88 with PPI), with optimal thresholds of ≥75 pg/mL (sensitivity 92 percent, specificity 100 percent) without PPI and ≥500 pg/mL (sensitivity 67 percent, specificity 96 percent) with PPI.

“Diagnosis of pernicious anaemia remains challenging in patients with vitamin B12 deficiency and isolated APCA because of their limited specificity,” the authors said. “Prior biomarker studies mostly excluded patients receiving PPIs.”