Fecal analysis

small intestine

Final breakdown and reabsorption of proteins, CHO, & fats

large intestine

• absorption of water, some minerals, and vitamins

• can absorb ~3000mL (3L) of water

diarrhea

• increase in daily stool weight above 200g

secretory

• Increased secretion of water due to enterotoxin-producing organisms

osmotic

• poor absorption due to incomplete breakdown (MALDIGESTION) or reabsorption of food (MALABSORPTION) which exerts osmotic pressure across the intestinal mucosa.

osmotic gap

290- [2 (Fecal sodium + fecal potassium)]

<50 Osm/kg

• Osmolal gap of secretory

>75 Osm/kg

• Osmolal gap of osmotic

>90 mmol/L

• Stool Na of secretory

<60 mmol/L

• Stool Na of osmotic

>5.6

• pH of secretory

• Reducing sugar: NEGATIVE

<5.3

• pH of osmotic

• Reducing sugar: POSITIVE

random

Types of specimen

• collected in plastic or glass containers and suitable for QUALItative testing of blood and microscopic examination of leukocytes, muscle fibers and fecal fats

3 day or 72 hour

Types of specimen

• collected in large containers for QUANTitative fecal fat testing

chemical preservations

• formalin

• 95% ethanol

• glycerol in NSS

• MIF,

• PVA

7.0 - 8.0

Normal values of Fecal

• pH?

100 to 200 g/day

Normal values of Fecal

• Quantity

gray

Macroscopic characteristics

red

Macroscopic characteristics

black

Macroscopic characteristics

steatorrhea

Consistency

• Bulky, frothy, greasy, spongy

bloody mucus clinging to fecal mass

Other mucus

invasive bacteria

Fecal Leukocytes

• 3 neutrophils/HPF (or any per OIF)

  • Salmonella

  • Shigella

  • Campylobacter

  • Yersinia

toxin producing bacteria

Fecal Leukocytes

• Absence neutrophils

  • S. aureus,

  • Vibrio spp

  • Viruses

  • Parasites

lactofferin latex agglutination test

Fecal Leukocytes: Methods

• available for detecting fecal leukocytes and remains sensitive in refrigerated and frozen specimens

• Positive result for diarrhea caused by invasive pathogens

creatorrhea

• Increased number of meat fibers

muscle fibers

• helpful in diagnosis and monitoring of patients with

  • pancreatic insufficiency

  • biliary obstruction

  • gastrocolic fistulas

undigested

Muscle Fibers

udigested, partially, digested

Muscle Fibers

7 grams

maldigestion

Evaluative causes of Steatorrhea

malabsorption

Evaluative causes of Steatorrhea

celiac disease

D-xylose test

Celiac

d xylose

itestinal, pancreatic

qualitative fecal test

Maldigestion

Qualitative fecal tests

Malabsorption

Qualitative fecal tests

neutral fat (tag)

fa salts soaps and fa

cholesterol

quantitative fecal testing

Van de kamer titration

Acid steatocrit

2.5 mL/150g

Guaiac based (gFOBT)

FOBT

false negative

FOBT: Guaiac based (gFOBT)

false positive

FOBT: Guaiac based (gFOBT)

Immunochemical based (iFOBT)

FOBT:

Porphyrin based FOBT = HEMOQUANT

FOBT:

apt test for fetal hemoglobin

Trypsin

fecal enzymes

Chymotrypsin

fecal enzymes

Elastase I

fecal enzymes

Dissaccharidase Deficienc

Copper reduction test (CLINITEST)

Carbohydrates

Serum carbohydrate tolerance test

Carbohydrates