gastric function tests and interpretation

Gastric function testsDr. S.Sethupathy

After overnight, 20-50- ml More than 100-120 ml – abnormal volume Causes: hypersecretion of acid Retention due to pyloric obstruction Regurgitation from duodenum Consistency- fluid No food particles Clear Red/dark red/ brown- ulcer ,bleeding Coffee ground – ca.stomach

Resting gastric juice

Bile- reflux gastritis Mucus- carcinoma stomach Free acid- 0-30 mmol/L More than 50 mmol/L – hyperacidity Total acid – 10- 40 mmol/L Organic acids- achlorhydria ,

hypochlorhydria

Gastric juice

Cancer stomach Perinicious anaemia Advanced gastritis

No acid – to investigate

Achylica gastrica

Two pieces of toast and tea or oat meal porridge

Residual content removed before meal Gastric juice collected at intervals Free acid more than 50 mmol/L –

duodenal,gastric ulcer, Zollinger Ellison syndrome, Pyloric stenosis, ch.cholecystitis

Fractional test meal

7% ethanol stimulation 100 ml Overnight fast , residual contents removed Sample every 15 mins Total and free acidity Easy to administer than oat meal Rapid and gastric emptying is better Unphysiological and free acid is more Caffeine S.Test -500mg in 200 ml - similar

to alcohol stimulation

Alcohol stimulation

Pentragastrin is a pentapeptide having the same terminal sequence of four amino acids - as gastrin

It is butyl oxy carbonyl-beta alanine-Trp-Met-Asp-Phe-CONH2

BAO, MAO, PAO are increased in Zollinger Ellison syndrome.

In atrophic gastritis, pernicious anemia and gastric carcinoma, there is achlorhydria.

Pentagastrin stimulation test

Histamine is a potent stimulus of gastric secretion

test is done by giving 0.04 mg/kg histamine s.c. Histamine fast achlorhydria is due to

pernicious anemia. Hypotension. Antihistamine to block H1 receptor effects of

histamine. Cimetidine, a H2 histamine receptor blocker is

used in peptic ulcer.

Augmented histamine test

Histamine analog – Histalog 3-beta amino ethyl pyrazole 10-50- mg No side effects

Histamine analog

Insulin stimulates HCl secretion Duodenal ulcer Hypoglycemia 15 units soluble iv

Insulin stimulation test (HOLLANDER’S)

Basal acid output (BAO) is less than 10 mmol/hour in males and less than 5.5 mmol/hour in females.

It is increased (more than 15 mmol/hour) in Zollinger Ellison syndrome.

Maximal acid output (MAO) is 7-45 mmol/hour and is after stimulation.

Peak acid output (PAO) after stimulation is 12-60 mmol/hour.

BAO MAO PAO

BAO, MAO, ratio

It is increased in gastrinoma, Zollinger Ellison syndrome.

Moderate elevation of gastrin is also seen in pernicious anemia, hyper secretion of gastrin by antral G cells and renal failure, proton pump inhibitors intake.

After secretin , serum gastrin level increases in ZES but not in other conditions.

Serum Gastrin

Condition serum gastrin (pg/ml) Normal < 500

Antral gastritis low to normal

Duodenal ulcer 300 - 500

Fundal gastritis 300 - 60,000

Z.E. syndrome 3,500 - 60,000

Serum gastrin levels

Pancreatic gastrin producing cells(Common) Gastric gastrin producing cells Peptic ulcer, diarrhea, steatorrhea Fasting serum gastrin- >1000pg/mL Secretin test- 2,5,10,15,20 mins –difference

> 200pg/mL

Zollinger syndrome

Gastric secretion is stimulated and after one hour, a dye bound to resin (Azure-A) is given orally.

Based on the surrounding pH, the resin releases the dye

It is absorbed and excreted in urine. The quantity of dye in urine indicates the

acidity of gastric juice. It rules out achlorhydria.

It is used as a screening test.

Tubeless gastric analysis

H.pylori infection is playing a role in acid peptic disease.

Urease enzyme The presence of urease- pyloric infection. Urea breath test 13 C, 14 C- urea Breath CO2 Serological tests – less reliable

Helicobacter pylori

Vitamin B12 deficiency is macrocytic anemia and c megaloblastic

Low serum vitamin B12 concentrations Pernicious anemia –intrinsic factor deficiency or to

intestinal malabsorption or dietary deficiency. The test involves - two orally administered test

doses of radioactive labelled vitamin B12 Measuring radioactivity in a urine specimen

collected for five hours. The first test dose -alone The 2nd test dose - three days later) - with intrinsic

factor.

The Schilling test

ConditionResults

1st Stage 2nd Stage

normal absorption absorptiondietary deficiency absorption absorption

intestinal disease malabsorption malabsorption

pernicious anemia malabsorption absorption

Limited but specific uses in certain conditions

Perinicious anaemia ZES Peptic ulcer Now endoscopy plays a major role Biopsy can be taken

Importance

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