Can celiac disease or Helicobacter pylori–associated gastritis cause iron deficiency without elevating CRP?

Gastrointestinal (GI) pathologies, specifically celiac disease and Helicobacter pylori–associated gastritis, are established drivers of iron deficiency (ID) and iron deficiency anemia (IDA). These conditions frequently present as occult causes of ID, often evading detection when practitioners rely solely on systemic inflammatory markers like C-reactive protein (CRP).

Clinical and effectiveness evidence

In cases of unexplained or refractory iron deficiency, underlying GI conditions are frequently identified upon further investigation.

• Celiac Disease: Approximately 3.2% to 4.2% of patients presenting with iron deficiency anemia are found to have celiac disease. In many cases, IDA is the sole presenting symptom, occurring in up to 10–15% of patients without classic diarrheal symptoms.
• H. pylori Gastritis: Chronic H. pylori infection is strongly associated with IDA, particularly in adult women. Meta-analyses demonstrate that H. pylori eradication significantly improves hemoglobin and serum ferritin levels, confirming the causative link between the infection and iron depletion.

Mechanistic explanations

These conditions impair iron status through distinct physiological pathways:

• Mucosal Damage (Celiac): Celiac disease causes villous atrophy in the duodenum, the primary site of iron absorption. This destruction reduces the surface area and the expression of essential transport proteins, such as divalent metal transporter 1 (DMT1) and ferroportin, directly blocking iron uptake.
• Acid Reduction and Sequestration (H. pylori): H. pylori induces chronic gastritis that can lead to hypochlorhydria (reduced stomach acid). This elevation in gastric pH prevents the conversion of dietary ferric iron (Fe³⁺) into the more soluble ferrous form (Fe²⁺) required for absorption. Additionally, the bacteria may sequester iron for their own metabolic needs and induce localized cytokine release that triggers hepcidin-mediated iron sequestration.

Diagnostic considerations and CRP

A critical clinical challenge is that both conditions can cause significant iron deficiency without elevating systemic inflammatory markers.

• Localized Inflammation: The inflammatory response in celiac disease is often sequestered within the intestinal mucosa (involving intraepithelial lymphocytes), while H. pylori remains localized to the gastric lining.
• CRP Sensitivity: Because these processes are often confined to the GI tract, they may not activate the systemic IL-6 signaling pathway required to trigger hepatic production of CRP. Consequently, a normal CRP level cannot be used to rule out these gastrointestinal causes of iron deficiency.

Bottom line

Celiac disease and H. pylori are primary causes of iron malabsorption that frequently occur with normal CRP levels. In patients with iron deficiency, a normal CRP does not exclude these GI conditions, and targeted diagnostic testing (e.g., serology or endoscopy) is often required.