Atrophic Gastritis and Calcium Deficiency
Yes, atrophic gastritis can cause calcium deficiency through impaired calcium absorption due to hypochlorhydria or achlorhydria, which reduces the dissolution and ionization of calcium salts necessary for proper absorption in the small intestine. 1, 2, 3
Mechanism of Calcium Malabsorption
The pathophysiology is straightforward and well-established:
Gastric acid is essential for calcium absorption because it dissolves poorly soluble calcium salts (particularly calcium carbonate) and converts them to ionized calcium (Ca²⁺), which is the form that can be absorbed in the proximal small intestine 2
Atrophic gastritis destroys parietal cells, leading to hypochlorhydria or achlorhydria (reduced or absent stomach acid production), which markedly impairs the dissolution and ionization of dietary calcium salts 1, 2
The acid-free or severely hypochlorhydric stomach that results from advanced atrophic gastritis creates a high-risk condition for calcium malabsorption and subsequent osteoporosis 2, 3
Clinical Context and Associated Deficiencies
Calcium deficiency in atrophic gastritis occurs alongside other well-documented nutritional deficiencies:
Multiple micronutrient deficiencies are common, with older persons having increased risk due to reduced nutrient bioavailability from gastrointestinal diseases like atrophic gastritis, specifically affecting vitamin B12, calcium, and iron absorption 1
Iron deficiency occurs in up to 50% of patients with corpus-predominant atrophic gastritis and typically presents earlier than vitamin B12 deficiency 4
Vitamin D deficiency is highly prevalent, occurring in the majority of atrophic gastritis patients, with mean levels significantly lower than healthy controls (18.8 vs. 27.0 ng/ml) 5, 6
The combination of calcium and vitamin D deficiency creates a particularly high risk for bone health complications 7, 6
Screening and Management Approach
All patients with atrophic gastritis should be evaluated for calcium status along with other micronutrient deficiencies:
Screen for calcium levels in conjunction with vitamin D, iron studies, and vitamin B12 in all patients with confirmed atrophic gastritis, particularly those with corpus-predominant disease 1, 4
Consider calcium supplementation in patients with documented deficiency, and these deficiencies should be corrected by supplementation 1
Use calcium citrate rather than calcium carbonate when supplementing patients with hypochlorhydria, as calcium citrate does not require gastric acid for absorption (this is standard clinical practice, though not explicitly stated in the provided evidence)
Important Clinical Pitfalls
Calcium deficiency may be overlooked because clinical attention often focuses on the more commonly discussed vitamin B12 and iron deficiencies in atrophic gastritis 7
Long-term consequences include osteoporosis risk, making calcium deficiency a significant concern for morbidity and quality of life, particularly in older patients who already have age-related bone density loss 2, 3
Severe atrophic gastritis with advanced gastric atrophy carries the highest risk for multiple nutritional deficiencies including calcium 3