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Management of the Bariatric Surgery Patient
Gastrointestinal Hormones
Gastrointestinal Hormones
TOP 10 TAKEAWAY MESSAGES:
Gastrointestinal (GI) Hormones
- Gastrointestinal hormones regulate caloric balance, hunger/ satiety food digestion, and nutrient utilization via central nervous system signaling, effects on GI motility, and GI enzyme release.
- Common GI hormone action in response to eating includes a decrease in hunger and facilitation of digestion (delayed gastric emptying, digestive enzyme release, and post-absorptive nutrient metabolism).
- The jejunum, the second longest segment of the small intestine, absorbs the greatest amount of simple sugars, fatty acids, proteins, minerals and vitamins.
- The ileum, the longest segment of the small intestine, absorbs bile salts, vitamin B12, some vitamins and some minerals.
- After food intake, most GI hormones decrease hunger/increase satiety.
- Among the few GI hormones that increase hunger between meals are ghrelin (“hunger hormone”) and neuropeptide Y (NPY). Positive caloric balance may not always be hunger-related.
- Illustrative GI hormones produced by the stomach include ghrelin and gastrin.
- Illustrative hormones produced by the pancreas include insulin, glucagon, pancreatic polypeptide (PP), amylin, and somatostatin.
- Illustrative GI hormones produced by the small intestine include cholecystokinin (CCK), secretin, motilin, and glucose-dependent insulinotropic peptide (GIP — also known as gastric inhibitory peptide).
- Illustrative GI hormones produced by the ileum and/or large intestine include fibroblast growth factor (FGF) 19, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and peptide YY (PYY).
Nutrient Absorption
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GI Hormone Regulation of Caloric Balance, Food Digestion, and Nutrient Utilization
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Illustrative Gastrointestinal Hormones and Function
Where Secreted | Gastrointestinal Hormone | Effect of Hormone on Eating Behavior | Effect of Eating on Hormone Secretion | Notes | Effect of Gastric By-pass and Sleeve Gastrectomy |
Stomach | Ghrelin (secreted by P/D1 cells) | ↑ Hunger | ↓ | ↑ With fasting ↑ Gastric emptying/ growth hormone (GH) | Ghrelin likely to decrease with sleeve gastrectomy (not so with gastric bypass) |
Gastrin (secreted by G cells in antrum) | ↓ Hunger | ↑ | ↑ Hydrochloride (HCI) acid and pepsinogen | ↓ Gastric bypass −/↑ Sleeve | |
Pancreas | Insulin (secreted by pancreatic beta cells) | ↓ Hunger | ↑ | ↑ Hunger with hypoglycemia ↑ Glucose transporter 4 in adipose tissue/muscle, glycogenesis, lipoprotein lipase activity, lipogenesis | ↓ Insulin resistance/ fasting insulin ↑ Insulin sensitivity/ insulin responsiveness |
Glucagon (secreted by pancreatic alpha cells) | ↓ Hunger | ↓ | ↑ Glycogen to glucose ↑ Postprandial glucagon in patients with type 2 diabetes mellitus (glucagon not suppressed) | Variable | |
PP [secreted by PP (F) cells] | ↓ Hunger | ↑ | ↓ Pancreatic exocrine secretion | Variable | |
Amylin (secreted by pancreatic beta cells) | ↓ Hunger | ↑ | ↓ Gastric emptying, glucagon | −/↓ | |
Somatostatin (secreted by D cells pylori antrum, duodenum, and pancreatic islets) | ↓ Hunger | ↑ | ↓ Growth hormone, gastrin, HCI, secretin, CCK, insulin, glucagon | −/↑ | |
Small Intestine (Mainly Duodenum and Jejunum) | CCK (secreted by I-cells) | ↓ Hunger | ↑ | ↑ Gall bladder contractility and bile, pancreatic enzymes ↓ Gastric emptying | ↑ Postprandial |
Secretin (secreted by S cells) | −− | ↑ | ↑ Pancreatic bicarbonate and bile ↓ Intestinal motility and gastric acid | Variable | |
GIP; Also known as Gastric Inhibitory Peptide – secreted by K cells | −− | ↑ | ↑ Insulin ↑ Glucagon postprandial | Variable | |
Motilin (secreted by M or Mo cells) | ↓ Hunger | ↓ (↑ with fasting) | ↑ Gastric motility, interdigestive migratory contractions (borborygmi) | ? | |
Ileum and/ or Large Intestine | FGF 19 [FGF 21 is produced by the liver] (secreted by ileal cells and regulated by farnesoid X receptors [FXR]) | ↓ Hunger | ↑ | ↓ Bile acids, glucose production ↑ Insulin sensitivity, glycogen synthesis | ↑ |
Glucagon like peptide-1 (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↑ Insulin ↓ Glucagon, gastric emptying | ↑ | |
Glucagon like peptide-2 (secreted by ileum/colon L-cells) | ↓ Hunger | ↑↑ | ↑ Glucose metabolism, intestinal mucosal growth, increases absorptive surface, epithelial brush-border nutrient transporters and digestive enzymes, intestinal blood flow, postprandial chylomicron secretion ↓ Gastrointestinal motility | ↑ | |
Oxyntomodulin (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↑ Glucagon-like peptide-1 (GLP-1) and glucagon receptor activity ↓ Gastric acid and gastric emptying | ↑ Gastric bypass − Sleeve gastrectomy | |
Peptide YY (secreted by ileum/colon L-cells) | ↓ Hunger | ↑ | ↓ Gall bladder and pancreatic secretions, gastric emptying | ↑ |
Bariatric Surgery
...tric Surgery
...P 10 TAKEAWAY MESSAGES: Bariatric Surgery...
...ariatric Surgery Poor Candidates Patient is no...
...al Bariatric Surgery Patient
...rgical ProceduresHaving trouble viewing table? Ex...
...tric Surgical Proced...
...ndoscopic Sleeve Gastroplasty (ESG) P...
...Mechanisms of Weight Loss with ESG R...
...ioperative and Post-Operative...
...ations Some medications that increase periop...
...ression Clear liquid diet (CLD): Anythin...
Complication...
...st 30 Days) General post-operative complic...
...e (>30 Days) Gastro-gastric fistula (RNY)...
...r Late Intestinal (small bowel) obstruc...
...fter Surgery Hair loss: Any weight loss can...
Nutrient Considerations
...ient Considerations...
...AY MESSAGES: Bariatric Surgery Nutrient...
...AKEAWAY MESSAGES: Microbiome The microb...
Common Micronutrient Deficienciesa Vitami...
Micronutrient Deficiency Replacement After Bariat...