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Monday, December 3, 2012

GASTROINTESTINAL FUNCTION TESTS


GASTROINTESTINAL FUNCTION TESTS

Indications:

Diagnosis of:

  • Gastric-ulcer/ Peptic-ulcer
  • Pernicious anaemia
  • Zollinger Ellison Syndrome
  • Completion of surgical vagotomy

Classification:

Examination of
  • resting juice content.
  • fractional gastric juice.
  • gastric juice after stimulation.

alcohol stimulation
caffeine
histamine
insulin/ pantagastrin

  • Tubeless gastric analysis (Azure-A-resin)/ cation exchange resin - excreted into urine (H+ conc) 

Sample collection: Ryle’s Tube

ABNORMALITIES OF GASTRIC FUNCTION:

Increased Gastric HCl: 

  1. Zollinger – Ellison Syndrome (a tumor of gastrin secreting cells of the pancreas)
  2. Chronic duodenal ulcer
  3. Excessive histamine production 

Decreased Gastric HCl:  Gastritis, gastric carcinoma, pernicious anaemia.


 TESTS FOR INTESTINAL FUNCTION:


Lactose Tolerance Test –
  • 50 gm lactose in 200 ml of water
  • Blood specimen at Fasting, 30, 60 and 120 minutes.
  • Normal : More than 30mg/dL.
  • 20-30mg/dL borderline and <20mg/dL - lactase deficiency


D-Xylose absorption test –
  • 25 gm (0.5 gm/kg body weight in children) in 250ml  water
  • blood level after 30’, 1 hr and 2 hrs.      (<25 mg/dL abnormal).
  • urine for 5 hrs (normally 4 gm excretion) (> 20%)
  • normal blood concentration with decreased urinary excretion ---> renal impairment/ incomplete urine collection

To differentiate pancreatic steatorrhoea and malabsorption steatorrhoea

Serum carotenoids –
e.g. lycopene, xanthophyll and carotene malabsorption  
carotenoids  (normal ranges 50 - 250mg/dL)

Fecal fat analysis –

  • normally 1 - 4gm/ 24 hrs (lipid free diet)
  • < 7gm / (lipid rich diet)
  • excretion in biliary obstruction
  • exocrine pancreatic insufficiency
  • diseases of small intestine


Qualitative screening test –
  • Sudan staining for fecal fat
  • Normally 40 to 50 small neutral lipid droplets/ high power


Quantitative fecal fat analysis –
  • 72 hrs stool collection
  • lipid rich diet for 2 days prior to test
  • 50 – 100 gm of lipid each day
  • reference range – 1 to 7gm/ 24 hrs 

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