Normal Lab Values

Question 1

Fecal Occult Blood Testing

Answer 1

Bleeding into gut, warns of cancer and other serious disease. Point of care kits may not pick up all pt with occult blood, so send stool specimen off if good history and physical suggests GI dz. Done every year on pt >50

Question 2

Defer Fecal Occult Blood Testing if

Answer 2

Diarrhea, colitis, constipation, diverticulitis, ulcers, hemorrhoid flare ups, period. (dont want cross contamination)

Question 3

Foods to avoid before Feccal Occult Blood Testing. Why?

Answer 3

Contiain heme or peroxidase (false +) or strong reducing agents (false -)
Beets, broccoli, Red meat, Vitamin C, horseradish

Question 4

Stomach Anatomy and Physiology

Answer 4

storing, mixing, moving food into intestines
secrete IF for B12 absorption
Different areas/cells have diff fxn

Question 5

Helicobacter pylori

Answer 5

microbe that is the cause of most stomach and duodenal ulcers, chronic stomach inflammation and long term stomach upset.

Question 6

Urea Breath Test

Answer 6

for H. pylori.

C13 or C14 given by mouth. If H. pylori present, it breaks down urea to CO2, which the test detects

Question 7

Biopsy Urease Test

Answer 7

for H. pylori
fragment of stomach or duodenal mucosa obtained on enoscopy dropped onto a gell that contains urea and pH indicator
ammonia generated from the urea by H. pylori changes the pH and color

Question 8

Direct visualization, biopsy

Answer 8

for H. pylori
flagellated gram - rod
endoscopy - look for mucosal erythema, erosions granularity and nodularity
organisms can be seen on HandE or special stains in gastric mucin lining the pits

Question 9

Seeing Helicobacter

Answer 9

Special stains: Geimsa, Diff Quick
Silver stains: Warthin-Starry, Gena, Dieterle silver
Immunohistochemistry and direct flourescent antibody testing used most often. KNOW WHAT Ab YOU NEED

Question 10

Autoimmune Gastritis

Answer 10

immune mediated injury to gastric oxyntic mucosa
Gastric pH is alkaline or neutral (achlorhydria)
Serum pepsinogen likely reduced
Ab against H/K Atpase
IF Ab can also be present - low serum B12

Question 11

Achlorhydria

Answer 11

decreased production of acid by parietal cells
most common atrophic gastritis
anti acid meds induce artificial achlorhydria
High serum gastrin, low serum pepsinogen
24 hr gastric acid profile (NG gube)

Question 12

Hyperchlorhydria

Answer 12

gastric pH<2
remember gastrin stimulates acid production
Zollinger-Ellison syndrome= neuroendocrine tumor secreting gastrin.

Question 13

Malabsorption vs Maldigestion

Answer 13

Malabsorption=SI not fxnl
Maldigestion= exocrine pancreas not fxnl
both present with discomort, diarrhea, weight loss
low serum albumin, low faat soluble vitamins

Question 14

Fecal fat testing

Answer 14

both malabsorption and maldigestion fecal fat increased above 6g/day. have both qualitative and quantitative (72hr)

Question 15

Pancreatic Insufficiency

Answer 15

Pancreas produces many enzymes for digestion, and many things gan cause pancreatic insufficiency
Fecal elastase 1 is current best screen. usually reduced if pancreatic fxn poor enough to cause illness

Question 16

Small Bowel Insufficiency

Answer 16

Malabsorption due to celiac sprue/gluten enteropathy, Chron’s regional enteritis and others
prevents absorption of nutrients, despite them being well digested.
can screen for underlying condition of malabsorption and complications

Question 17

Things you may screen for in Small Bowel insufficiency

Answer 17

B12, Vit D, Vit A; PTT, Celiac disease, cystic fibrosis, pancreatic fxn, methylmalonic acid, hydrogen breath test, xylose absorption test, lactose absorption

Question 18

Other Testing for Small Bowel Insufficiency

Answer 18

Ultrasound, CT, endoscopy, ERCP endoscopic retrograde pancreatography

Question 19

D-xylose test

Answer 19

Screen for small bowel insufficiency
sugar taken by mouth, if small bowel normal, it is found in blood and urine soon after
Draw blood at 2 hrs. Collect all urine for 5hrs
Test is not routinely used

Question 20

D-xylose test: Results

Answer 20

High blood xylose and low urine levels suggests renal dysfxn
Low blood and urine levels suggest poor absorption (bacteria, parasites, short bowel, celiac)
Follow up with abnormal results

Question 21

Blind Loop Syndrome

Answer 21

small bowel bacterial overgrowth syndrome
follows bypass surgery, bacteria overgrow where there is less movement of food
bacteria produce products that interfere with absorption of nutrients
LOOK FOR DEFECTS IN ABSORBING VARIUS SUGARS AND BILE SALTS. diagnosis= quantitating the bacteria

Question 22

Malabsorption/Maldigestion impact on other labs

Answer 22

Albumin, total calcium, and BUN =LOW
Cholesterol=LOW
PT prolonged (lack VitK)
Decreased levels of Vit A,D,E,K (fat soluble)

Question 23

Gluten and Gliadin Sensitivity

Answer 23

Serologic tests, Biopsy tests

Important - Patient must be consuming gliadin for test to be positive, otherwise false negative will result

Question 24

Serologic Tests for Gluten and Gliadin Sensitivity

Answer 24

tTG -IgA has highest sensitivity and specificity
EMA
DGP IgA and IgG antibody is specific for celiac
IgA and EMA tends to decrease in 3-6 months, so useful for monitoring pt compliance, but may be too low for initial diagnosis

Question 25

Biopsy in Gluten sensitivity

Answer 25

Celiac disease= gross attenuated or absent vili | villous atrophy and cronic inflammation. count epithelial cells relative to lymphocytes

Question 26

Dermatitis herpetiformis biopsy

Answer 26

some ppl with celiac will develop this biopsy erythematous skin including that adjacent to lesions initially neutrophils develop around abcess, eosinophils may move in as progresses granular IgA deposits along tips of dermal papillae

Question 27

Lactose intolerance

Answer 27

lack of enzyme required to cleave lactose, unable to absorb it Diagnosis made based on history Hydrogen breath test (increased if +) Stool acidity measures lactic acid

Question 28

Disaccharidase deficiency

Answer 28

congenital/genetic or acquired from damage to SI brush border food challenge, withdrawl then rechallenge various breath tests, biopsy of small bowel

Question 29

Vasoactive intestinal poly peptide

Answer 29

can be produced ectopically by endocrine tumors and MEN-1 syndromes watery diarrhea, comfirmed by serum measurement

Question 30

Stool Culture

Answer 30

used to detect enteral bacterial infections | plates checked at 24 and 48 hrs

Question 31

Microscopic examination of stool

Answer 31

to detect ova and parasites in specimen. | 3 parts: direct wet mount, wet mount of stool concentrate, and preparation of permanent smear with staining

Question 32

Immune methods to detect organisms

Answer 32

immunologic techniques to detect a host of bacteria, prtozoans and helminths in stool

Question 33

Giardia Diagnosis

Answer 33

diagnosed on duodenal aspirate or biopsy when history is not classic. "bald professor" appearance under microscope

Question 34

The Trasnaminases

Answer 34

AST/SGOT ALT/SGPT included in general metabolic panel for general screening released form hepatocytes that are even mildly injured. AST comes from many different kinds of cells. ALT is specific for liver and lesser extend sk. m.

Question 35

Transaminitis

Answer 35

differential diagnosis when they are elevated, consider repeating test in two weeks off all alcohol and unneded meds, will "cure" may patients. otherwise assuming your patient complied, you'll need to consider several very serious treatable illnesses. proceed with lab workup

Question 36

AST/ALT Ratio

Answer 36

normal 1.15:1 (and in individuals with liver disease not related to alcohol abuse) 2-6 associated with liver disease intra hepatic cholestasis >1.5 Acute viral hepatitis .5-.8

Question 37

Bilirubin

Answer 37

Unconjugated (indirect) elevated, pt may have hemolysis or problem conjugating conjugated (direct) elevated, pt may have bile flow blockage both elevated probably damage to liver cells

Question 38

Urobilinogen

Answer 38

measured routinely on urinalysis. produced by gut flora working on bilirubin, mostly removed by liver. high levels suggest hemolysis or hepatocellular insufficiency

Question 39

Liver and alkaline phosphatase

Answer 39

elevated suggests cholestasis keep in mine physiologically higher in growing young adults, pregnancy, etc. CONTEXT important.

Question 40

CFTR Chloride Transporter

Answer 40

deficiency causes cystic fibrosis. sweat chloride test immunoreative trypsinogen performed on drop of blood.

Question 41

Wilson's disease

Answer 41

ATP7B copper transport required to remove excess copper is defective 24 hour urine copper level is very high in symptomatic patients. to confirm=genetic studies

Question 42

HFE mutations - Hemochromatosis

Answer 42

Iron overload involving GI tract (liver, pancreas) transferrin saturation and serum ferritin to screeen. pitfalls - someone who takes an iron pill or someone who is ill from other causes

Question 43

Alpha One antitrypsin deficiency

Answer 43

liver failure and emphysema serum antitrypsin assay. however, if patient is not in usu state of health, it will be elevated biopsy or genetic screening may be req'd

Question 44

Autoimmune hepatitis

Answer 44

``` elevated antinublear antibodies. most common autoantibody is anti-f-actin anti LKM (liver kidney microsome) defines the less common variant ```

Question 45

Primary Biliary Cirrhosis

Answer 45

small bile ducts are destroyed by autoimmunity | lab tests look for antimitochondrial Abs esp antibodies against pyruvate dehydrogenase

Question 46

Alcohol Abuse

Answer 46

lab tests suggest heavy drinking, but wont give diagnosis elevated transaminases, esp AST:ALT ratio around 2 elevated red cell mean corpuscular volume is a warning (but has other causes) as liver failure advances, proonged PT, low albumin AST around 400-1000 suggests alcoholic hepatitis. gamma glutamyl transferase or ethylene glucuronide to monitor sobriety

Question 47

Ethylene glucuronide

Answer 47

used in sobriety programs to monitor sobirety, bc made when person drinks alcohol, and stays in blood and urine for a day or more.

Question 48

Metabolic Syndrome

Answer 48

more common cause of fatty liver/ elevated transaminases than alcoholism. lower MCV, AST/ALT ratio around usual 1.

Question 49

Pancreatitis - Acute

Answer 49

medical emergency. physical exam and imaging are key. lab can vonfirm by finding elevated amylase and or lipase from injured cells. order blood and urine bc low urine despite high serum indicates macroamylasemia. (amylase autoantibody)

Question 50

Serum amylase

Answer 50

diagnosis of acute pancreatits. valuse 4-6 times the upper reference range. Urine and serum levels rise parallel, but urine may remain higher longer

Question 51

Serum lipase

Answer 51

acute pancreatitis lipase 5-10 times upper reference range rise within 4-8 hours, remain so for 7-14 days. levels not indicative of severity

Question 52

Chronic Pancreatitis

Answer 52

loss of most of exocrine pancreas. diagnosis made on history, endoscopy, imaging, maldigestion labs less helpful, though many patients have low serum trypsin/trypsinogen bc many pancreatic acinar cells no longer present