IRT level is elevated, an infant may have cystic fibrosis; an infant or adult may have abnormal pancreatic enzyme production, pancreatitis, or pancreatic cancer; or the elevated IRT may be a false positive. Elevated levels need to be followed with further testing.
Tests for gastric, duodenal secretions
MV GASATAYA, M.D.
• The mucous membrane of the stomach has tubular
gastric glands that secrete:
1. Hydrochloric acid
• From the parietal cells
• Needed to convert pepsinogen to pepsin
•Hydrolyze polypeptides and disaccharides directly
• From the goblet cells and the mucous glands
• Protective to stomach wall
•Complex mixture of mucoproteins and
3. Intrinsic factor
• From the parietal cells
• Is required for vitamin B12 absorption
Gastric secretions – cont.
- gastric secretion contains all the electrolytes found in
other body fluids in a combined osmolar concentration equal to
or slightly greater than plasma.
5. Digestive Enzymes
PEPSIN – major digestive enzyme of gastric secretion
- secreted by chief/peptic cells as 2 proenzymes:
pepsinogen and zymogen (activated by gastric acid)
- catalyzes degradation of proteins to proteases and
OTHER DIGESTIVE ENZYMES (GASTRIC)
- Gastric lipase = digestion of dietary fat
- renin (chymosin) = secreted by chief cells
- gastricsin (pepsinogen C)
6. Non-Digestive Enzymes:
LDH, aspartate amino transferase, isocitric
dehydrogenase, alkaline phosphatase
Secretions of the Small Intestine
• In addition to mucous-secreting goblet cells, there are many
specialized mucous-secreting glands (Brunner’s glands) that secrete a
thick, alkaline mucus in response to certain stimuli
• Enzymes in the membranes of the microvilli include:
• Peptidase – breaks down peptides into amino acids
• Sucrase, maltase, lactase – break down disaccharides into
• Lipase – breaks down fats into fatty acids and glycerol
• Enterokinase – converts trypsinogen to trypsin
• Somatostatin – hormone that inhibits acid secretion by
• Cholecystokinin – hormone that inhibits gastric glands,
stimulates pancreas to release enzymes in pancreatic juice, and
stimulates the gallbladder to release bile
• Secretin – stimulates the pancreas to release bicarbonate ions in
Examination of Gastric Contents
1. To determine if the patient can secrete gastric acid
2. To measure the amt. of acid produced by a patient with
symptoms of peptic ulcer
3. To support a hypersecretory state characteristic of
4. To determine the completeness of vagotomy
5. To aid in the differential diagnosis of gastric ulcer from
Summary: to evaluate the possibility of hyperchlorhydria or
ADDITIONAL PROCEDURES NOW IN USE
FOR THE DETECTION OF THESE
1. Direct examination of lesion by endoscopy
2. Improved radiologic techniques – air contrast
3. pH sensitive electrodes that will transmit pH readings
when passed into the stomach
4. measurement of serum gastrin levels
5. cytologic exam of gastric contents for malignant cells
6. immunologic testing of serum for the precense of antiintrinsic factor and antiparietal cell antibodies seen in
By nasal or oral intubation of the Px. A Levin Tube is
passed thru the nose or a Rehfuss or similar tube is passed
thru the mouth. Performed in a fasting state.
To ensure complete collection, position of the tube is
checked by flouroscopic examination of the stomach
Px. Should be instructed not to swallow excessive
amounts of saliva during collection since it would
neutralize gastric acidity
Acidity testing is routinely performed on 15-min. interval
specimens. Aspirate placed in time labeled containers that
represent each 15 min of the required collection period &
not as a single specimen.
ROUTINE GASTRIC ANALYSIS
1. PHYSICAL APPEARANCE
- normal fasting gastric secretion is pale gray, translucent,
slightly viscous fluid with a fairly pungent odor.
- after a 12-hr. fast-presence of food particles is abnormal
& indicates delayed gastric emptying, often a result of
- large amounts of bile produces a yellow green aspirate
- blood = from other gastric lesions: gastritis, ulcer, CA or
can be from lesions in mouth, nasopharynx or respi tract
-if bld is present, confirm by orthotoluidine or guaic tests
- Gastroccult = a guaic based slide test specifically designed for
detecting occult blood in gastric secretions
- measured in ml. & is used with titrable acidity to determine
total acid output. Volume should increase following gastric
- pH meter used and correlation with the titrable acidity values
- Anacidity =failure to produce pH less than 6.0 following
4. TITRABLE ACIDITY
- currently the measurement of overall H+ conc. is the
- both the ionized & un-ionized hydrogen are measured
simultaneously by titrating the specimen with 0.1 N
NaOH to pH 7.0
- using the indicator phenol red, which changes from
yellow to red in the pH range of 6.6 to 8.0
- titration results are reported as milliequivqlents or
millimoles per liter of titratable acid
- milliequivalents/L of titratable acid are calculated
Calculate the milliequivalents/L of titrable acid in a 20 ml
specimen when 2.0 ml. of 0.1N NaOH are used to reach
pH 7.0 (x=mEq/L of titrable acid in 20 ml specimen)
(0.1N NaOH)(2 ml.) = (x)(20 ml.)
0.2 = 20x
x = 0.2 = 0.01 equivalents/L*
1N = equiv/L
1 equiv = 1000 mEq
x = 0.01 x 1000
x = 10 mEq/L of titratable acid
Because titrable acidity represents mEq or mmol/L and the
typical gastric secretion specimen is of considerably less
volume, it also becomes necessary to calculate the
ACTUAL ACID OUTPUT.
ACTUAL ACID OUTPUT
= specimen volume in liters X titrable acidity
The first 15-min. specimen of a 1 hr. basal collection has a
volume of 25 ml. To titrate 10 ml. of this specimen to the
end point of phenol red, 5 ml. of 0.1N naOH is used.
Calculate the: A) Titrable acidity
B) acid output of the patient
A. (0.1N NaOH )(5 ml. ) = x(10 ml.)
0.5 = 10x
x = 0.5 = 0.05 equiv./L
(0.05 equiv./L)(1000) = 50 mEq/L (titratable acidity)
B. 25 ml x 50 = 1.25 mEq /L (acid output)
BASAL GASTRIC ACIDITY
Basal Gastric Specimen is a 1-hr. collection, usually
consisting of four 15-min fasting specimens
The volume, pH, titrable acidity and acid output of the
sample that constitute the basal specimen are determined
Normal values for volume and acidity are based on the
total 1 hour specimen, so individual sample results must
be combined to provide the 1-hr. interval
BASAL ACID OUTPUT is the sum of all the acid
outputs of the four 15-min basal samples
In general, the normal basal secretion has a volume of
about 30-60 ml. & contains a low acid output of approx.
1 to 4 mEq/hr.
Major Diagnostic Value:
markedly elevated acidity = indicative of ZollingerEllison Syndrome (condition of hypersecretion of gastric
acid due to a gastrin-secreting tumor of the pancreas)
POST STIMULATION GASTRIC
Inability to produce gastric acid cannot be determined just
from the analysis of basal gastric secretion alone
Need to perform post-stimulation gastric acidity tests
which utilize the principle of introducing a gastric
stimulant into the patient ff. the basal collection.
The stimulant of choice = PENTAGASTRIN – a synthetic
compound resembling gastrin & does not cause the patient
discomfort that occurs with histamine administration.
Pentagastrin produces a more rapid response than histalog.
(subQ = 6ug/kg body weight)
When pentagastrin or histamine is used as a stimulant
specimens are collected at 15-min. intervals for 1 hr.
following the injection.
All post-stimulation specimens are analyzed in the same
manner as the Basal specimen by measuring volume, pH,
titrable acidity & calculating the actual acid output.
The hourly acid output is calculated and is now referred as
the MAXIMUM ACID OUTPUT.
The PEAK ACID OUTPUT which is considered more
reproducible by some laboratories is also determiend by
taking the total of the two-highest 15-min acid outputs and
multiplying this figure by 2 to arrive at the hourly acid
Acid ouputs in mEq/L
Stimulated specimen #1 = 1.95
2 = 6.0 highest
3 = 6.2
4 = 4.5
Peak Acid Output = 6.0 + 6.2 = 12.2 X 2 = 24.4 mEq/hr
-using pentagastrin, the peak acidity is usually seen within
15-45 min. post injection
-normal values are again variable. However, normal
individuals will usually not produce a maximum acid
output over 40 mEq.
Normal individuals will exhibit a fall in pH to below 3.5
Hourly basal & maximum outputs that are representative of
conditions that produce abnormal gastric acidity are
provided in the table:
MICROSCOPIC EXAM. OF
Structures seen in the normal stomach:
= erythrocytes, leukocytes, epithelial cells, yeast,
bacteria, & particles of mucus
Cellular elements are usually in various stages of
autolysis so difficult to identify
-Erythrocytes=in small amounts – of no consequence
-Leukocytes=can be of gastric origin or from swallowed
secretions. Increased numbers can result from
inflammation of gastric mucousa, mouth or URT.
-Epithelial cells :
Squamous cells – can be dislodged from mouth, nose,
pharynx or esophagus
Columnar cells- significant increase in gastritis
Mycobactrial species = in pulmonary TB
Heliobacter (Campylobacter) pylori – antral gastritis with
gastric and duodenal ulcerations. H. pylori is charac.
found in or under the mucus layer of enterocytes.
Yeasts = large numbers in the retention of gastic contents,
such as pyloric obstruction
G. lamblia trophocytes or cysts, Strongyloides larvae or
ascaris or hookworm ova can also be found
INSULIN HYPOGLYCEMIA TEST
Hypoglycemia resulting from administration of insulin
is a potent stimulus to gastric secretion
Major component of stimulus is transmitted by the
vagus nerves & this can be abolished by vagotomy
Valid only if the blood glucose falls below 50 mg/dl at
some point in the test = usually after 30 min of insulin
Vagotomy is complete if the acid output in the greater
of the 2 post-insulin hours is less than the greater of
the 2 basal hour
Incomplete vagotomy = if the acid output in the 2 hr. post
insulin period exceeds that of the 2 hr. basal period by
more than 0.5 mEq OR if there is an acid output greater
than 2 mEq in either basal hr.
1. Intubation of patient after a 12-hr. overnight fast. A
2-hr. basal secretion is obtained in 15-min. samples.
2. Blood sample for glucose determination is taken upon
completion of the basal secretion study & at 30, 60 & 90
min. after insulin injection.
3. Insulin is administered intravenously either at a fixed
dosage of 15 or 20 units or at a calculated dosage of
0.20 units/kg. body weight. It is essential that a 50 ml.
syringe filled with 50% (w/v) glucose solution be
readily available for IV injection
4. Gastric secretion is collected in 15 min. samples for 2
hrs. after insulin injection.
5. For each basal and post-insulin gastric sample =
determine the volume, titrable acidity & acid output.
TUBELESS GASTRIC ANALYSIS
Use of an orally administered ion-exchange resin to detect
the presence of H+ in gastric fluid
Marketed under the trade name, DIAGNEX BLUE
Based on the use of a carboxyl-acid cationic resin
(amberlite XE-96) with an innocuous indicator dye,
Azure A coupled to it.
H+ in gastric secretion combined with the resin & liberate
azure-A ions, which are then absorbed into the
bloodstream in the small intestine and subsequently
excreted in the urine.
- In principle, the presence of H+ in the gastric fluid can be
determined by an estimate of the urine Azure A
- Caffeine sodium benzoate was used as a gastric stimuant
- Many sources of false (+) and false (-) and quantification
of gastric acid is not possible
Relative contradictions for
2. Prothrombin time >3 seconds over control
3. Platelet count <100,000/microliter
4. Bleeding time less than 10 min
5. Coma, unless patient is intubated
6. Myocardial ischemia
7. Thoracic aortic aneurysm
9. Zenker’s diverticulum
COMPOSITION OF DUODENAL CONTENTS
1. Endocrine Pancreatic Secretions
3. Intestinal Secretion (Succus entericus) mixed with
Pancreatic Exocrine Secretion (Major contributor to
=exceeds 1,500 ml per day in normal adult
=colorless, clear, non-viscid, alkaline solution (pH aprox. 8)
PANCREATIC EXOCRINE SECRETION
1. 1 to 2% ORGANIC MATERIAL, mostly enzymes or
their precursors (Trypsinogen, chymotrypsinogen,
amylase, lipase, lecithinase, elastase, collagenase, leucine
aminopepetidase & various esterases)
2. 1% INORGNIC MATERIAL
Sodium = major cation
Bicarbonate = major anion
Na+ & K+ are present in the same conc. in serum while
Ca++ & Mg+ are present in lower concentration
The HCO3 conc. varies directly with the rate of pancreatic
secretion, while chloride varies inversely with the rate of
secretion, so that the sum of these 2 ions remain constant.
STIMULI TO PANCREATIC EXOCRINE SECRETION
1. Vagal Stimulus – relatively slight & results in a small vol. of
secretion that is rich in enzymes.
2. Hormonal Stimuli (2 subst. secreted by duodenal mucousa)
A. Secretin = HCl stimulates its release and results in a
copious flow of pancreatic secretion that is low in
enzyme content & high in HCO3.
B. Pancreozymin = (Cholecystokinin) stimulate the pancreas
to secrete enzymes
*Gastrin = weak stimulus but may cause pancreatic exocrine
Approx. 500-1000 ml. enters the duodenum daily
usually alkaline (pH 7.0-8.5), color:yellow to brown/green
Contains bile salts (chiefly sodium glycholate &
taurocholate), billirubin pigments, cholesterol,
phospholipids, various inorganic salts.
Alkaline phosphatase = only enzyme present in significant
amount but no function in digestion.
daily volume is not known
Contains a variety of digestive enzymes that are capable
of breaking down ingested foods but enzymatic activities
are considered to be relatively weak
COLLECTION OF FLUID
Done by duodenal intubation in the fasting state using:
1. a double lumen tube (Diamond or Dreiling tube)
2. a three lumen tube
3. certain types of instruments for small bowel biopsies
= tube is equipped with a radiopaque tip thus position can be
- In the fasting state, the residual content of the duodenum
varies up to 20 ml.
- Fluid is transparent or slightly translucent, pearl gray and
moderately viscid, slightly turbid if with gastric secretions
- Slight blood streaking = from the intubation procedure
*large amt. of bld. = suggest CA of Ampulla of Vater
*presence of food particles = indicates either pyloric
obstruction or pyloric stenosis
*sediment or flocculent debris = inflamm. of duodenal
mucosa, pancreas or biliary tract
MICROS. EXAM. OF CELLULAR ELEMENTS
-should be collected in containers chilled in an ice bath &
-examined unstained following centrifugation
-Normal: few leukocytes or epithelial cells
*increased # of PMN & exfoliated epith. cells with or
without masses of bacteria, enmeshed in mucus = inflam.
of the duodenum, bile ducts or pancreas
*parasites = rarely seen are larvae of S. stercoralis, cyst
or troph of G. lamblia or E. hist., ova of hookworm or
SUBST. THAT ENHANCE BILE FLOW
=subs. which increase bile secretion by the hepatic cells
ex. Bile salts and secretin
=increase bile flow by causing the contraction of the gall
bladder and relaxation of the sphincter of the common bile
ex. Magnesium sulfate
CHEMICAL EXAMINATION OF DUODENAL
I. EXAMINATION OF STIMULATED BILE
Duodenal intubation is performed. Following aspiration of the
residual content, 50 to 100 ml. of sterile 25% saturated
MgSO4 is introduced through the duodenal tube. After a
minute or so, the MgSO4 & duodenal contents are aspirated,
the collections are pooled and discarded until a yellow bile
first appears, requiring about 2-10 ml.
Three fractions of the bile are subsequently collected in
“A” Bile – the first to appear which is light yellow & watey
After 1 to 3 minutes, it will normally give way abruptly
to a viscid deep yellow brown bile – the “B” bile.
Eventually, the bile again becomes pale yellow and watery
which is the “C” bile.
“A” Bile usually amounts to 5 to 20 ml.
“B” Bile is about 30-75 ml.
Absence of “B” Bile may be seen in:
Advanced Cholecyctitis, Cholelithiasis with
Obstruction of the Cystic Duct or Cholecyctctomy
The finding of Bile Sand (deep red-brown bile
microscopically seen as cholesterol crystals or calcium
bilirubinate) is highly suggestive of cholelithiasis or
calculus in the biliary tract.
Culture of stimulated Bile:
Coliform organisms, staphylococci, B-hemolytic
streptococci, enterococci and various species of
salmonella are often found in an acute or chronic
cholecystitis and cholangitis.
TESTS FOR PANCREATIC FUNCTION
1. Determination of Amylase & Body Fluids
- for the diagnosis of acute & chronic pancreatitis =
increased levels of pancreatic enzymes in the blood &
2. Immunoreactive Trypsin Det. In plasma by RIA
3. Secretin Test – the exocrine secretory function of the
pancreas can be assessed by duodenal intubation &
subjecting the pancreas to stimulation with secretin &
pancreozymin. Includes measurement of the volume &
quantitative analysis of pancreatic juice for HCO3 &
enzyme content specifically Amylase activity.
4. Augmented Secretin Test
- of particular value since augmented stimulation enhance
secretory deficiencies as in inflammation & CA.
5. Miscellaneous Tests:
A. Leukocytosis & wbc count sometimes reaching
30,000/ cu mm. in acute pancreatitis
B. decreasing serum calcium – points to a more serious
from of pancreatitis
C. hyperbilirubinemia & other liver function tests – with
D. Test for malabsorption syndrome (caused by
inadequacy of pancreatic secretion resulting from chronic
pancreatitis or pancreatic CA)
1. serum carotenoid level
2. glucose tolerance test
3. c-labeled triglyceride breath test
4. starch tolerance test
5. 3-day fecal fat determination
6. d-xylose test (useful to distinguish malabsorption
syndrome caused by pancreatic disorders from that of
E. Tests for Cystic Fibrosis (mucoviscidosis) of the
Characterized by abnormal secretion of by the various
exocrine glands of the body including the pancreas,
salivary glands, peritracheal & peribronchial glands. The
laboratory diagnosis depends largely of the increase of Na
and Cl in the sweat.
Principle: Pilocarpine is iontophoresed into the skin to
stimulate locally – increased sweat gland secretion. The
resulting sweat is absorbed by filter paper or gauze pad,
weighed, diluted with water and analyzed for Na & Cl
F. Recent Tests that provide a better indicator of pancreatic
function as well as diagnosis of pancreatic carcinoma /CA
1. Lactoferrin determination in pancreatic juice
- lactoferrin is higher in patients with chronic
pancreatitis than in patients with pancreatic carcinoma
2. Det. of Galactosyltransferase Isoenzyme II
- found to be raised in pancreatic CA, but is nonspecific; may be elevated in other GIT CA.
3. Tubeless techniques with oral administration of Nbenzal-L-tyrosyl-p-aminobenzoic acid.