Sorted By Test Name - Mayo Medical Laboratories

FGIP
90171
GAST
8512
1 0.35-0.69 Equivocal
2 0.70-3.49 Positive
3 3.50-17.4 Positive
4 17.5-49.9 Strongly positive
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management by
Laboratory Methods. 21st edition. Edited by RA McPherson, MR Pincus. New York, WB Saunders
Company, 2007, Chapter 53, Part VI, pp 961-971
Gastric Inhibitory Polypeptide (GIP)
Clinical Information: Gastric Inhibitory Peptide is a 43 amino acid peptide structurally related to
Glucagon and Secretin and is found in the mucosa of upper intestine produced by K cells. GIP was
originally detected as a factor inhibiting the secretion of gastric acid and Gastrin secretion. Its major
action has now been determined to be a potent stimulant of B cells to release Insulin and is also known as
Glucose-Dependent Insulinotropic Peptide. Exaggerated increases in GIP are noted after glucose
administration to patients with Pancreatitis. This increase is also seen in patients with Diabetes Mellitus.
GIP levels are decreased by Calcitonin. Elevated levels are present in cases of Verner-Morrison
Syndrome.
Reference Values:
Fasting: Up to 50 pg/ml
Postprandial: 110 - 720 pg/ml
Test Performed by: Inter Science Institute
944 West Hyde Park
Inglewood, CA 90302
Gastrin, Serum
Clinical Information: Gastrin is a peptide hormone produced by mucosal G cells of the gastric
antrum. It is synthesized as preprogastrin, cleaved to progastrin, which undergoes several posttranslational
modifications, in particular sulfation, and is finally processed into the mature 34-amino acid, gastrin-34.
Gastrin-34 may be cleaved further into the shorter 17-amino acid, gastrin-17. Either may be secreted as a
c-terminal amidated or unamidated isoform. A number of additional, smaller gastrin fragments, as well as
gastrin molecules with atypical posttranslational modifications (eg, absent sulfation), may also be secreted
in small quantities. Gastrin half-life is short, 5 minutes for amidated gastrin-17, and 20 to 25 minutes for
amidated gastrin-34. Elimination occurs through peptidase cleavage and renal excretion. Gastrin-17 I
(nonsulfated form) and gastrin-17 II (sulfated) appear equipotent. Their biological effects are chiefly
associated with the amidated isoforms and consist of promotion of gastric epithelial cell proliferation and
differentiation to acid-secreting cells, direct promotion of acid secretion, and indirect stimulation of acid
production through histamine release. In addition, gastrin stimulates gastric motility and release of pepsin
and intrinsic factor. Most gastrin isoforms with atypical posttranslational modifications and most small
gastrin fragments display reduced or absent bioactivity. This assay measures predominately gastrin-17.
Larger precursors and smaller fragments have little or no cross-reactivity in the assay. Intraluminal
stomach pH is the main factor regulating gastrin production and secretion. Rising gastric pH levels result
in increasing serum gastrin levels, while falling pH levels are associated with mounting somatostatin
production in gastric D cells. Somatostatin, in turn, downregulates gastrin synthesis and release. Other,
weaker factors that stimulate gastrin secretion are gastric distention, protein-rich foods, and elevated
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