Iron deficiency in autoimmune gastritis

Background. IIron deficiency (nonanemic iron deficiency and iron-deficiency anemia) remains the most common condition in the general clinical practice. Iron deficiency negatively affects the prognosis of the underlying disease and reduces the quality of patient’s life. One of the most common and difficult-to-diagnose cause of iron deficiency in clinical practice is autoimmune gastritis.

Objective. The aim of the study was to determine the incidence of iron deficiency (nonanemic iron deficiency and iron-deficiency anemia) in patients with autoimmune gastritis and to identify the factors contributing to its development.

Material and methods. Sixty-two patients previously diagnosed with autoimmune gastritis were included in a cohort observational study. The mean age of patients was 53.5 ± 12.6 years (from 25 to 79 years). By gender, there were predominantly females – 52 (83.9%), and 10 (16.1%) males. All patients underwent laboratory tests: complete blood count, iron metabolism parameters (ferritin, serum iron), antiparietal cell antibodies, anti-intrinsic factor antibodies, serological biomarkers of gastric atrophy.

Results. According to the patients’ history data and laboratory tests, iron deficiency was determined in 38 (61.3%) patients. At the time of inclusion to the study, iron-deficiency anemia was found in 7 (11.3%), anemia of complex etiology (iron deficiency and vitamin B12 deficiency) – in 2 (3.2%), nonanemic iron deficiency (ferritin < 30 μg/l) – in 8 (12.9%) patients. According to the hemoglobin level anemia grade was mild in the majority of patients – 21 (70.0%), moderate – in 6 (20.0%), severe – in 3 (10.0%) patients. The time period between iron-deficiency anemia detection and diagnosing of autoimmune gastritis ranged from several months to 25 years, with average mean 48.7 months (SD = 67.39). The frequency of iron deficiency among females and males was different –67.3% and 30.0%, respectively (χ² = 4.92, p = 0.027; OR = 4,08 [95% CI 1.103-20.923]). Iron deficiency was more common among women of reproductive age then among menopausal women (80.0% vs 29.6%, χ2 = 13.252, p < 0.001; OR = 9,5 [95% CI 2,637-34,227]). Serological biomarkers of gastric atrophy (pepsinogen I < 30 μg/L, pepsinogen I/pepsinogen II ratio < 3.0) were detected more frequently in patients with iron deficiency than in patients without them (89.5% vs 58.3%, χ² = 8.160, p = 0.005; OR = 6.071 [95% CI 1.628-22.638]). Iron deficiency was detected in all patients with hypothyroidism, while in patients with euthyroidism it was less common (100% vs 36.8%, χ² = 7.287, p = 0.007). Oral iron supplements were noneffective in 60.5% of patients and were associated with adverse events in 23.7% of patients.

Conclusion. Autoimmune gastritis should be included in the differential diagnosis of iron deficiency of unknown etiology, especially in cases of refractoriness to oral iron supplements. Nonanemic iron deficiency and iron-deficiency anemia in autoimmune gastritis develop primarily due to a decrease in acid production and proteolytic activity of the stomach, and additional factors include female gender, reproductive age, and hypothyroidism.

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