Gastric Secretory Disease Flashcards
What are the causes of elevated acid secretion?
Elevated Gastrin
Elevated vagal tone
Elevated histamine (mastocytosis, basophilic granulocytic leukemia)
Elevated parietal cell mass/idiopathic
Paraneoplastic syndrome (non-gastrin: rare)
When is gastrin expected to be elevated?
Is antrum pH indicative of gastrin levels?
Expected response to reduced delivery of acid to antrum
Elevation can occur independent of antrum pH
What is Zollinger-Ellison Syndrome?
What are the types?
How is the prognosis for each?
Where is each localized?
Gastrin secreting neuroendocrine tumor
Isolated gastrinoma (75%)
Can be localized and removed
Duodenum and pancreas
Multiple Endocrine Neoplasia I (25%)
Multifocal, not curable
Associated HPTH, other islet cell tumors
What are the essential diagnostic features of ZE syndrome?
Elevated basal acid secretion (15 mEq/hr)
Gastrin > 150 pg/ml (>1000 with low pH is diagnostic)
Secretin stimulation increases gastrin > 120 pg/ml
PPI use can cause false negative results
What are the two main manifestations of ZE and what consequences are associated with them?
More severe ulcer disease
Extends distal duodenum/jejunum
Relapsing ulcer, high PPI dose to cure
Diarrhea
Large acidic fluid volume
Inactivation of pancreatic enzymes
Hypokalemia, steatorrhea, weight loss
What are the alternative causes for gastrin elevation?
H. pylori
Antral G-cell hyperplasia
Gastric outlet obstruction
Retained antrum from gastric surgery
Cysteamine treatment
Showt bowel syndrome
Renal failure
What are the causes of low acid secretion?
Medications - PPI, H2RA, Anti-cholinergics
Inflammatory destruction of parietal cells (gastritis)
Acute H. pyloriinfection
Vagal injury/transection
VIP producing tumors
What aare the consequences of low acid secretion?
Overall well tolerated with modern diet; impaired protein digestion
Impaired absorption of Fe, Ca, B12
Gastric bacterial overgrowth
Enteric infections/TB
Small bowel bacterial overgrowth
Impaired delivery of certain drugs
What is intrinsic factor?
What produces it?
What conditions affect its secretion?
IF: Carrier glycoprotein that binds to Vitamin B12 to permit active transport in ileum
Produced by parietal cell
Conditions affecting acid secretion affect IF secretion (not PPI)
What is the procedure of the Schilling Test?
Replace B12 parenterally
24 hr urine collection of radiolabeled B12 orally
If low repeat while giving IF
If still low, repeat after empiric antibiotic treatment for SBBO
If still low: pancreatic insufficiency or terminal ileal diseae
What causes pepsin/lipase reduced secretion?
What are the effects of protein/lipase reduced secretion?
Affected by conditions that inhibit acid secretion (not PPI for lipase)
Perhaps less important for digestion with modern diet
Play a role in killing ingested infectious agents
What causes reduced secretion of bicarbonate/mucous?
What is the major consequence?
Causes similar to those affected gastric acid secretion
In addition, affected by inhibition of prostaglandin synthesis (NSAIDs)
Major consequence: mucosal injury
