Miscellaneous Urine Testing and Fecal Testing Flashcards

(46 cards)

1
Q

Phsyiologic process that leads to eventual hemosiderin in the blood

A
  1. RBCs break in the lumen of the vessel
  2. Haptoglobin picks up the free hemoglobin
  3. Haptoglobin-hemoglobin complex goes to the liver for further catabolism
  4. Any unbound hemoglobin is filtered by the glomerulus and enters the urine
  5. PCT reabsorbs hemoglobin and will catabolize to form biliverdin (degrades into bilirubin) and ferritin
  6. Ferritin denatures into hemosiderin
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2
Q

Ferritin

- Water solubility

A

Water soluble

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3
Q

Ferritin

- Visibility w/ a light microscope

A

Not visible w/ a light microscope

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4
Q

Ferritin

- Visibility w/ an iron stain

A

Prussian blue negative

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5
Q

Hemosiderin

- Water solubility

A

Insoluble in water

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6
Q

Hemosiderin

- Visiblity w/ a light microscope

A

Visible w/ a light microscope

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7
Q

Hemosiderin

- Visibility w/ iron stain

A

Prussian blue positive

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8
Q

Causes of hemosiderinuria

A
  • Intravascular hemolysis
  • Ineffective erythropoietin
  • Diseases requiring multiple blood txns
  • Primary hemochromatosis
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9
Q

What does hemosiderin look like in a urine analysis?

A
  • Will be found either free, w/in renal tubular cells, or in casts
  • Yellow-brownish in color
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10
Q

What is the time delay b/w the hemolytic episode and the formation of hemosiderin granules?

A

Hemosiderinuria is positive 2-3 days after an acute hemolytic episode and may persist for weeks for patients w/ or w/o a healthy liver

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11
Q

____ is uncommon in patients w/ a healthy liver

A

Bilirubinuria

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12
Q

Causes of myoglobinuria

A
  • Rhabdomylosis
  • Trauma (crushing injury to muscle, extensive muscular activity, myocardial infarction, contact sports)
  • Infections (sometimes w/ EBV and influenza)
  • Toxins (Alcohol, CO, angel dust = PCP)
  • Primary muscle diseases (polymyositis, dermatomyositis)
  • Hereditary (Familial Paroxysmal Myoglobinuria)
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13
Q

____ is extremely toxic to the kidneys

A

Myoglobin

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14
Q

If myoglobin is positive in the urine, physicians may induce diuresis w/ ____ or perform ____ ____ in order to prevent renal damage

A

Mannitol; renal dialysis

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15
Q

What does myoglobin look like in the urine?

A
  • Urine is red if fresh; light brown or black upon standing
  • RBCs may be in sediment
  • Reduced urine volume
  • Positive reagent strip for hemoglobin/blood
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16
Q

Two confirmatory methods for myoglobinuria

A
  • Chromatography

- Ammonium Sulfate Method

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17
Q

Describe the ammonium sulfate confirmatory test

A
  • Causes hemoglobin to precipitate out of solution

- Positive strip testing following the addition of ammonium sulfate and centrifugation will confirm

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18
Q

Three types of diarrhea

A
  • Secretory
  • Osmotic
  • Hypermobility
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19
Q

Secretory diarrhea

  • “Definition”
  • What causes it?
A
  • Def: increased secretion of water into the lumen

- Caused by enterotoxin-producing organisms

20
Q

Osmotic diarrhea

  • “Definition”
  • What causes it?
A
  • Def: injection of osmotically active solutes preventing water absorption
  • Caused by maldigestion and/or malabsorption
21
Q

What causes maldigestion leading to osmotic diarrhea?

A
  • Def: pancreatic or hepatic disorder preventing the conversion of foodstuffs into readily absorbable substances
  • Caused by lactose intolerance, fructose intolerance
22
Q

What causes malabsorption leading to osmotic diarrhe?

A
  • Def: normal digestive ability but inability to properly absorb foodstuffs
  • Caused by celiac disease, tropical sprue, ulcerative colitis, surgical procedures
23
Q

Hypermobility diarrhea

  • “Definition”
  • What acuases it?
A
  • Def: decreases fecal matter’s transit time

- Caused by laxatives, fibers, nerves, hormones, emotions, gasterectomy, gastric bypass

24
Q

Why is stool brown?

A

Urobilinogen → stercobilinogen → urobilin

25
Appearance | - Pale stool = ?
Blockage of bile duct preventing conjugated bilirubin from entering the small intestine
26
Appearance | - Black tarry stool = ?
Blood from eosphagus, stomach, duodenum | - Blood from colon usually appears bright red
27
Appearance | - Small-hard stools = ?
Constipation
28
Appearance | - Slender ribbon-like stools = ?
Obstruction
29
Appearance | - Mucus-coated stool = ?
Intestinal inflammation or irritation (Crohns and colitis)
30
This occurs when fecal fat exceeds 7g/day
Steatorrhea
31
What causes malabsorption leading to steatorrhea?
- Celiac disease - Lymphoma - Whipple's disease
32
What causes maldigestion leading to steatorrhea?
- ↓ pancreatic enzymes → pancreatitis, cystic fibrosis, pancreatic cancer - ↓ bile acid enzymes → hepatocellualr disease, bile duct obstruction
33
Steatorrhea | - Physical characteristics
Pale, greasy, spongy, pasty, extremely foul smelling
34
Steatorrhea | - Stains
Sudan III, Sudan IV, Oil Red O stains (neutral fats stain an orange-red color)
35
How many fat globules of neutral fat/hpf will normal feces contain?
< 60 globules/hpf; patients w/ steatorrhea will have more
36
Steatorrhea | - Polarized microscopy
?
37
Two methods of occult blood testing
- Guaiac-based fecal occult blood (hemoccult) | - Immunochemical fecal occult blood (hemosure)
38
Guaiac-based fecal occult blood | - Principle
Based on the pseudoperoxidase properties of hemoglobin, other peroxidasess will interfere
39
Guaiac-based fecal occult blood | - Sensitivity
Not very sensitive so it won't detect the normal amounts of blood found in stool
40
Guaiac-based fecal occult blood | - Specificity
?
41
Immunochemical fecal occult blood | - Principle
Uses polyclonal Abs directed aginst the globin portion of UNDEGRADED human hemoglobin (blood from LARGE intestine)
42
Immunochemical fecal occult blood | - Sensitivity
Since hemoglobin will degrade in the GI system, these tests are most sensitive to hemoglobin originating in the large intestine
43
Immunochemical fecal occult blood | - Specificity
?
44
Guaiac-based fecal occultl blood | - False positives
- Rare red meats - Certain vegetables and fruits - Salicylates and NSAIDS (w/in prior to 7 days)
45
Guaiac-based fecal occult blood | - False negatives
Ascorbic acid
46
Apt test | - Principle
- Used to test fetal feces for the presence of maternal blood - Based on relative resistance of fetal hemoglobin to alkali denaturation compared to adult hemoglobin A - Adult hemoglobin denatures to yellow-brown hematin in alkali solutions