What investigations should I consider for a patient with suspected chronic gastritis?

For a patient with suspected chronic gastritis, initial investigations should focus on detecting Helicobacter pylori infection, as it is a common and treatable cause. The recommended tests are the carbon-13 urea breath test or the stool antigen test, both of which have high sensitivity and specificity (~95%) and are preferred in primary care settings. It is important to ensure the patient has not taken proton pump inhibitors (PPIs) for at least 2 weeks or antibiotics for 4 weeks prior to testing to avoid false negatives. Serological testing is generally not recommended due to poor positive predictive value and inability to distinguish active from past infection, except where locally validated tests are available ¹,⁴.

If H. pylori infection is confirmed, eradication therapy should be offered, tailored to antibiotic history and allergies, to reduce gastritis progression and risk of complications such as peptic ulcer disease and gastric malignancy ¹,⁴.

In cases where symptoms persist despite eradication or if H. pylori is excluded, consider endoscopic evaluation to assess mucosal changes, exclude malignancy, and obtain biopsies for histological confirmation of chronic gastritis and to identify other causes such as autoimmune gastritis or rare conditions. Endoscopy is particularly indicated if alarm features are present or symptoms are refractory to initial management ¹,⁴.

Additional laboratory tests may include full blood count to check for anemia, and in selected cases, serum gastrin or intrinsic factor antibodies if autoimmune gastritis is suspected. However, these are usually guided by clinical context and specialist advice ¹.

Recent literature highlights advances in diagnostic modalities for H. pylori, including molecular methods and improved non-invasive tests, but current UK guidelines prioritize breath and stool antigen tests for initial diagnosis in primary care ¹(Ghazanfar et al., 2024).