ua 11

occult blood

colorectal cancer screening, anemia investigation, guaiac and immunochemical method

guaiac vs immunochemical method

pseudoperoxidase activity of hgb= color change vs ab specific for human hgb, false neg- stool not dry, heat breaks down hgb if closed container, too much hgb> prozone

fecal leukocytes

ulcerative colitis, infectious diarrhea, wright stain

fecal fats and elastase

pancreatic insufficiency, quantitative testing

feces specimen contain

bacteria, cellulose, undigested food, GI secretions, bile pig, intestinal wall cells, electrolytes, water, 100-200 g excreted/24hrs

small intestine

main site of breakdown and reabsorption of proteins, carbs, fats, aided by pancreatic enzymes and bile salts

digestive tract

9000 mL of ingested fluid saliva gastic, liver, pancreatic, and intestinal secretions enter/day, most are reabsorbed, 150 excreted in feces

excess water

>3000 reaching large intestine= diarrhea

diarrhea

>200 g stool/day with high liquid more than 3/day, >4 week chronic, <4 acute, pH <5.6 sugar malabsorption, Na K osmolarity= fecal osmotic gap

diarrhea factors

illness duration, mechanism (secretory, osmotic, altered motility), severity, stool characteristics

fecal osmolarity

290, gap 290 [2x (Na + K)], osmolarity diarrhea >75, secretory diarrhea <50 high electrolytes

secretory diarrhea

bacterial, viral, protozoan infec> high secretion of water and electrolytes, drugs laxatives hormones, inflam bowl disease, endocrine disorder, malignancy, collagen vascular disease, <50 mOsm

osmotic diarrhea

poor absorption exerts pressure across intestinal mucosa, incomplete digestion or reabsorption(malnut) of food high water retention in large intestine, lactose intolerance, celiac sprue, (malabsorption), poorly absorbed sugars, amebiasis, abx, laxatives, antacids, >75 mOsm

IBS

hyper motility and constipation (stool in colon longer, water reabsorbed by fecal), caused by food, chemicals, stress, exercise

healthy emptying vs rapid gastric emptying RGE

35-100 min, based on age/gender vs dumping syndrome <35 min, early- symp 10-30 min, late 2-3 hrs

altered motility in

IBS, RGE, Gastrectomy, gastric bypass, post-vagotomy status, Zollinger-Ellison syndrome, duodenal ulcer, diabetes mellitus

steatorrhea

>6 g/day of fat in stool, pancreatic insufficiency, malabsorption, lack of bile salts (triglyceride digestion), malignancy, cystic fibrosis

maldigestion vs malabsorption

impaired breakdown of food (lack of pancreatic enzymes or bile salts) vs impaired uptake of nutrients by the intestine

d-xylose test for malabsorption

low level in urine, not digested but is reabsorbed to appear in urine, if norm maldigestion

causes of malabsorption

bacteria overgrowth, intestinal resection, celiac, chrons, tropical sprue, lymphoma, whipple disease, giardia lamblia infestation, intestinal ischemia

quantitative collection

72 hrs, time required to pass through intestine, open container slowly due to gas accumulation

brown stool vs pale acholic

urobilin vs bile duct blockage, barium sulfate

blood stool

red-black depending on digestive tract area bleeding, black- upper, meds, iron, bismuth, charcoal, red-lower, beets

green stool

abx, bilirubin to biliverdin

ribbon like stool

obstruction

steatorrhea stool appearance

pale, bulky, frothy, foul odor, greasy, floats

mucus coated stool vs blood streaked mucus

intestinal irritation, inflammation, colitis, Chron’s, colon cancer, straining vs intestinal wall damage, dysentery, malignancy, report both

primary neutrophils in feces

in bacterial dysentery by Salmonella, Shigella, Campylobacter, Yersinia, and E. coli bs invade intestinal wall; bacterial toxins; staph, Vibrio no leukocytes

microscopic exam

wet prep, methylene blue, wrights or GS for pos or neg bacteria, 3 neutrophils/hpf sig, any neutroph/oil 70% sig for invasive bac

lactoferrin latex agglutination

older specimens, fridge or frozen, lactoferrin is in neutrophil granules

methylene blue stain procedure for leukocytes

mucus or drop of liquid stool on slide, add 2 drops Loffler methylene blue, mix with wooden stick, stand 2-3 min, examine neutrophils on hpf

muscle fibers

pancreatic insufficiency, CF, undigested striated muscle, pts must eat red meat before collection

muscle fibers slides

feces in 10% alc eosin, examine for 5 min, count fibers w/ well preserved striations, undigested- vertical & horizontal striations, partial- in 1 direction, digested- none, >10 undigested abnorm

qualitative decal fats

microscope screening for steatorrhea, lipids- neutral fat (trig), fatty acid salts (soap), FA and cholesterol, 2 part test- neutral and split

neutral fat vs split fat

large red-orange droplets, 60/hpf= steatorrhea vs more indicitive of steatorrhea

neutral fat staining procedure

homogenize 1 part stool w/ 2 parts water, mix stool w/ 1 drop 95% ethyl alc on slide, + 2 drops saturated sudan III in 95% ethanol, mix, cover slip, hpf

split fat stain

free FA and FA from soap hydrolysis and neutral fats, 100<4um/hpf norm, 100 1-8 slight increase, 100 6-75 increase, cholesterol crystals after heating and cooling

split fat stain procedure

mix stool w/ 1 drop of 35% acetic acid, +2 drops saturated sudan III, mix, cover slip, heat gently almost boiling, hpf

fecal occult (hidden) blood testing FOBT

black tarry- upper GI tract, lower- red, 2.5 mL of blood/150 g stool sig, mass screening, yearly >50 yr old, high predictive value for colorectal cancer

guaiac based fecal occult blood tests

pseudoperoxidase activity of hgb, hgb + H2O2 + guaiac pseudoperoxidase> oxidized guaiac (BLUE) + H2O

guaiac

less sensitive than UA reagent bc up to 2.5 mL of blood in stool norm, no false pos from vegetable, bacterial peroxidases and diet

guaiac lab testing

commercial kits with guaiac impregnated filter paper, several test areas, pos and neg control

guaiac lab testing procedure

apply stool to 2-3 testing areas, samples from diff areas of stool (hemorrhoids), add peroxide to back of filter paper containing stool and controls, blue= pos

commercial guaiac testing kit pt instructions

2 sample from 3 diff stool confirm neg, 3 days no red meat horseradish melons broccoli cauliflower turnips vit C iron, 7 days aspirin anti inflam agents, testing 7 days

immunochemical fecal occult blood test iFOBT

more sensitive, antihuman hgb abs specific for globin portion of hgb, colorectal cancer, only detects GI bleed (less false pos)

porphyrin based fecal occult blood test

measure intact hgb and hgb converted to prophyrins, false pos from upper GI bleed or nonhuman source of blood- no red meat 3 days, ref lab

porphyrin based fecal occult blood test false pos

aspirin anti inflam med, red mean, horseradish, raw broccoli, cauliflower, radishes, turnips, melons, menstral and hemorrhoid contaimination

porphyrin based fecal occult blood test false neg

vit C >250, iron supplement with vit C, not waiting specific time after sample is applied to add the developer agent

quantitative fecal fat testing

confirms steatorrhea, 3 day collection with diet and fat restriction (50-150g/d of fat 2-3 d before and during collection), Van de Kamer titration

quantitative fecal fat specimen collection

large preweighed container, fridge to slow bacterial actions (gases)

Van de Kamer titration

FA titrated to neutral endpoint with NaOH, quantitates fat testing to confirm steatorrhea

fecal fat reporting

grams of fat or coefficient of fat retention based on 100g/d intake of fat, 1-6 g/d or coefficient of fat retention of at least 95%

coefficient of fat retention equation

dietary fat- fecal fat / dietary fat x 100

hydrogen nuclear magnetic resonance spec H NMR

quantitative fecal fat test, rapid 5 min, safe, specimen is microwaved dried and analyzed

acid steatocrit

rapid estimate of fat, monitors therapy, screen for peds, 5g specimen homogenized & acidified, spin in reg hct tube, measure length of fatty top layer & length of solid bottom layer

acid steatocrit calculation

fatty layer in cm/ fatty layer + solid layer cm x 100, adults <31%,

kids <15, [0.1939 x acid steatocrit%]- o.2174, kids <10%, >20 abnorm

near infrared reflectance spec NIRS

48-72 hr collection, scan surface of stool with infrared light 1400-2600 nM, calculate with calibration curve, quantitates water fat and nitrogen

APT test (fecal hgb)

checking blood stool and vomit that swallowed mom blood, pink= alkali resistant, yellow-brown maternal hgb

APT test (fecal hgb) procedure

specimen in water, centrifuge, pink supernatant into 2 tubes, +1% NaOH to 1 tube, 2 min, compare color w/ control (cord blood & adult blood)

APT test (fecal hgb) interference

maternal thalassemia major due to high HbF

fecal enzymes- pancreatic

associated with pancreatic insufficiency and CF, trypsin, chymotrypsin, elastase-1

classic trypsin test vs chymotrypsin

stool dissolves in gelatin on x-ray paper, not very sensitive vs more sensitive, less degraded, measure woth spectro

elastase-1

isoenzyme, high concentrations, resists degradation by gastric motility and mucosal defects, pancreas specific, differentiates panc from nonpanc steatorrhea

elastase-1 ELISA

immunoassay kit, single specimen, monoclonal ab

carbs

high in stool by osmotic diarrgea bc excess water needed to remove, due to inability to reabsorb or lack of digestive enzymes

carbs- idiopathic, maldigestion, malabsorption

lactase def in Africa asia S european Greek pop; lactose tolerance test; D-xylose tolerance test

carb testing on infants

pH- fermentation of excess carbs by intestinal bacteria, 7-8, <5.5= high carbs, clinitest, distinguish carb and bacterial/viral caused diarrhea

clinitest of carbs

1 part stool in 2 parts water, perform routine test, >0.5= carb intolerance, if pos do tolerance test

Which condition is most likely to cause osmotic diarrhea?

Disaccharidase deficiency