Pepsinogen I Blood Test (PGI)

Pepsinogen I (PGI) is a proenzyme produced almost exclusively by the chief cells of the gastric mucosa, and its concentration in the blood reflects the functional mass of the gastric glands. This test is particularly useful for individuals with chronic indigestion, a family history of gastric cancer, known or suspected chronic atrophic gastritis, pernicious anaemia, or Helicobacter pylori infection, and for those being monitored for gastric mucosal atrophy. A simple blood sample is analysed using an immunoassay to quantify circulating PGI, giving a reliable, non-invasive indication of gastric mucosal status without the need for endoscopy.

The test screens for:

Gastric Mucosal Biomarker
- Pepsinogen I (PGI): the primary proenzyme secreted by gastric chief cells. Reduced serum PGI is a recognised marker of chronic atrophic gastritis and gastric mucosal atrophy, while markedly elevated levels can be seen in certain inflammatory or hyperplastic states. The PGI level, and in particular the PGI:PGII ratio when measured alongside pepsinogen II, is widely used as a serological screen for gastric cancer risk and for monitoring the progression of atrophic changes in the stomach lining.

Why it matters
Gastric atrophy and chronic atrophic gastritis often develop silently over many years and are established precursors to gastric cancer. Measuring PGI provides an early, accessible signal of mucosal deterioration, allowing clinicians to identify at-risk individuals, guide decisions about endoscopy, and monitor the effect of treatment for H. pylori or other gastric conditions. For patients, it offers a straightforward blood test that can reveal important information about stomach health long before symptoms become severe.