II. Physiology
- Polypeptide secreted by the gastric mucosa
- Increases secretion of Stomach digestive substances
- Gastric acid
- Pepsin
- Intrinsic Factor
- Factors that increase Gastrin
- Vagus Nerve Stimulation
- Duodenal Distention
- Peptides within Stomach
- Factor that decrease Gastrin
- Secretin
- Gastric inhibitory peptide
- Increased Stomach acidity (low pH)
III. Labs
- Normal Serum Gastrin: <180 pg/ml
IV. Causes: Increased - Most important causes
- Medications (most common cause)
- Proton Pump Inhibitors (e.g. Omeprazole)
- Associated with 2-5 fold increase in Gastrin level
- H2 Blockers
- Proton Pump Inhibitors (e.g. Omeprazole)
-
Pernicious Anemia
- Very low Stomach acid level (contrast with Zollinger-Ellison)
- Zollinger-Ellison Syndrome or Gastrinoma (rare)
- Very high Gastrin level
- Gastrin Level remains increased despite withdrawal of Proton Pump Inhibitors and other possible causes
- High Stomach acid level
- Measured with nasogastric suction over one hour
- Contrast with very low Stomach acid level in Pernicious Anemia
V. Causes: Increased - Other Causes
- Hyperparathyroidism
- Retained gastric antrum
- Chronic atrophic Gastritis
- Pyloric obstruction
- Gastric neoplasm
- Chronic Renal Failure