Gastrin

The cut-off applies to a fasting sample off acid-lowering medicines; UK specialist labs commonly print below 40 pmol/L, while labs reporting in ng/L print figures such as below 100, and the printed cut-off is the one to use.

Gastrin is a hormone made by cells in the lower part of the stomach that tells the stomach to make acid. When there is plenty of acid, gastrin falls; when acid is low or blocked, gastrin rises. It is measured mainly to look for a rare gastrin-producing tumour, and to help understand low stomach acid.

It is a specialist test requested when ulcers keep returning or appear in unusual places, when there is severe reflux with diarrhoea, or in families with an inherited endocrine tumour condition, to look for a gastrinoma. It is also used in the work-up of pernicious anaemia and atrophic gastritis, where it runs high because the stomach makes little acid.

• Acid-lowering medicines of the proton pump inhibitor class (omeprazole, lansoprazole and similar), which commonly raise it several-fold
• Atrophic gastritis and pernicious anaemia, where the stomach makes little acid
• Helicobacter pylori infection
• Gastrinoma (Zollinger-Ellison syndrome), which is rare
• Long-term kidney disease
• A recent meal, and previous stomach surgery

• A value below the cut-off is the expected finding
• Fasting, in the general population
• Rarely, after removal of the lower part of the stomach

• Proton pump inhibitors are by far the commonest reason for a raised value; they are usually stopped for two weeks before the test under medical supervision
• A non-fasting sample reads higher
• Kidney disease raises it
• The sample must be separated and frozen promptly or it breaks down

Fasting overnight, off proton pump inhibitors for at least two weeks (and other acid-lowering tablets for a shorter time) under medical supervision, into a tube that is chilled, separated and frozen promptly. It is sent to a specialist laboratory.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.