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Senior - GU Test 1 > 4 - Lab Testing > Flashcards

4 - Lab Testing Flashcards

1
Q

He said

A

This stuff is high yield, maybe focus a little more on it

But i’m not your mom do what you want

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2
Q

Pt evals for suspected renal disease must include (at a min):

A
  • H/P
  • UA w dipstick/microscope
  • BUN and
  • serum creatinine
  • assessment of GFR
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3
Q

UA is aka?

A

Poor man’s renal biopsy

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4
Q

Urine is assessed for?

A

Assessed for:

  • Apperance
  • chemical test (dipstick)
  • microscopic exam
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5
Q

Preferred collection method?

A

Clean catch, midstream sample

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6
Q

What does the exam of the urine sediment tell you?

A

Valuable clues about renal parenchyma

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7
Q

Apperiance factors for urine?

A

Color
Clarity
Odor

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8
Q

Urine color indicates?

A

Normally clear-dark yellow

Color darkens

  • H concentration (dehydration)
  • myoglobinuria
  • bilirubinuria
  • kidney disease

Color changes:

  • orange: phhenazopyrieind, nitrofurantoin, rifampin, metrnidazol
  • pink: hemolysis

Pic on slide 11

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9
Q

Clarity values?

A
  • cloudy -> pyruia and suspended crystals

- alkaline urine

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10
Q

Examples of normal results and dipstick pics?

A

Slides 12-16

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11
Q

What is leukocyte esterase?

A

An enzyme produced by neutrophils

POS: WBCs in urine

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12
Q

False pos/neg for leukocyte esterase?

A

False pos: contamination

False neg: glycosuria, concentrated urine, drugs, not waiting long enough for testing

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13
Q

What causes nitrites?

A

Many gram-neg bacteria (esp e. Coli) can reduce nitrate to nitrite

1st morning void is best

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14
Q

Positive nitrite?

A

Bacterial infection

- neg doesnt r/o bacterial infection

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15
Q

Trace protein =

A

= 150mg

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16
Q

Protein indicates?

A

Usually 1st indication of renal disease

Mostly albumin on dipsticks

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17
Q

Normal pH?

A
  1. 0-6.0 - 1st morning sample
  2. 5-8.0 - random samples

The dipstick shows 5.0-8.5 so random is basically useless

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18
Q

Urinary pH is useful in the diagnosis of?

A

UTIs
Urinary stone
Disease
Renal tubular acidosis

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19
Q

Blood is 7.4ish so how does urine get more acidic?

A

Glomerular filtrate enters the tubule at normal physiologic pH (7.4) and acidifies in the DCT and collecting duct

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20
Q

What does the blood square measure?

A

Intact erythrocytes
Free hemoglobin
Myoglobin

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21
Q

False pos/neg blood?

A

False pos: menses, concentrated urine

False neg: high ascorbic acid

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22
Q

Normal specific gravity?

A

1.005-1.030

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23
Q

Spec gives indication of?

A

Insight into

  • urine osmolality
  • dehydration and shock (high)
  • overhydration or impaired ability to concentrate (lower)
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24
Q

Ketones

A

Detects acetic acid

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25
Q

Normal urobilinogen?

A

0.2-1.0mg/dL

(Shows as “normal” on the dipstick

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26
Q

Where does urobilinogen come from?

A

Formed in intestinal tract by bacterial breakdown
of conjugated bilirubin
– 50% reabsorbed into portal circulation & reprocessed
by liver
– small amount is normally excreted in urine
– majority is excreted via feces

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27
Q

High urobilinogen suggest?

A

Hemolysis
Hepatocellular disease
- hepatitis and cirrhosis

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28
Q

If you still dont understand the bili process

A

Slide 32 has a pic

Cant hurt its only been taught 5-6 times maybe this time itll stick

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29
Q

High bilirubin in serum (bilirubinemia) leads to:

A

Bilirubinuria (bilirubin in the urine)(normally urine should have NO bilirubin)

Suggest hepatocellular disease

  • liver can’t clear conjugated bili
  • cirrhosis or hepatitis
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30
Q

Normal glucose?

A

<0.1% (below the sensitivity level of UA dipstick)

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31
Q

How is the microscopic analyses processed?

A

Centrifuged urine sediment exam under microscope

You must request “micro”

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32
Q

What is “significant” level of erythrocytes?

A

> 3 RBCs per HPF (high power field)

The need a further workup

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33
Q

RBC appearance/morphology?

A

Round/normal: disease in epithelial tract

Dysmorphic: (irregular) nephrotic syndrome

Creanated (shrunken/scalloped) concentrated urine

Cell ghosts: swollen RBCs due to dilute urine

Regular ghosts: paranormal infection

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34
Q

Presence of leukocytes (microscopic)

A

Pyuria

> 5 leukocytes per HPF

35
Q

Leukocyte findings?

A

Neutorphils - bacteria
Eosinophils - allergic interstitial nephritis

Pyuria - UT injury

36
Q

sterile pyuria?

A

WBC present but neg culture

37
Q

Other causes of pyuria?

A 
– Stones
– Strictures
– Neoplasm
– GU tuberculosis
– Glomerulonephropathy
– Interstitial nephritis
38
Q

Epithelial cell findings?

A

Squamous epithelial - contamination

Transitional (urothelial cells)

  • normal (maybe)
  • neoplasm
39
Q

Renal tubular epithelial cells?

A

Clinically relevant

Diagnostic for ischemic/nephrotic acute tubular necrosis (ATN)

40
Q

Casts are?

A

Formed in distal convoluted tubules (DCTs) and collecting ducts

Named by shape and origin

41
Q

Casts suggest?

A

Renal parenchymal disease

42
Q

red cell casts?

A

Bleeding

Hallmark of glomerulonephritis

43
Q

White cell casts

A

Acute pyelonephritis
- also seen in acute interstitial nephritis (eosinophils)

Useful in distinguishing acute pyelonephritis from lower tract infection

44
Q

Renal tubular epithelial cell casts

A

Sloughed tubular cells -> acute tubular necrosis (ATN)

45
Q

Granular casts

A

Aka muddy brown casts

degenerating cells of various origins

  • nonspecific but pathologic
  • ATN maybe
46
Q

Waxy casts

A

Severe urine stasis in renal tubules

- chronic renal failure

47
Q

Broad casts?

A

Tubules are dilated and atrophic

  • chronic parenchymal disease
  • severe urinary stasis
  • ESR failure
48
Q

Fatty casts?

A

Numerous renal disease

- esp nephrotic syndrome

49
Q

Hyaline casts

A

Associated w/

  • concentrated urine
  • febrile disease
  • strenuous exe
  • diuretic therapy

Not specific

50
Q

Urine crystals formation depends on?

A
  • concentration
  • urine pH
  • presence/absence of crystallization inhibitors
51
Q

Crystal types?

A 
– Uric Acid
– Calcium phosphate &amp; Oxalate
– Cystine → hereditary cystinuria
– Struvite → “infection stones”; urease producing
organisms such as Proteus or Klebsiella
52
Q

Bacteria in urine is called?

A

Bacteriuria

Get a culture

53
Q

MC yeast in urine?

A

Candida albicans

54
Q

Yeast is common in?

A 
– Elderly (esp., female) 
– Antibiotic use 
– Diabetes 
– Catheter use 
– Post-surgery

Buds and hyphae

55
Q

Trichomonas looks like?

A

Pear shaped

Flagellated

56
Q

Urine culture is ordered if?

A

Cases of suspected UTI or pyelonephritis

Not necessarily a reflexive order

57
Q

Example CMP, BMP report?

A

Slides 58,59

58
Q

What is urea?

A

End product of protein catabolism

Excreted principally by glomerular filtration

59
Q

Serum marker of urea level?

A

BUN (blood urea nitrogen)

60
Q

Normal BUN?

A

5-20 mg/dL

61
Q

BUN increase w/:

A
  • acute/chronic renal failure
  • obstruction/stone
  • dehydration
62
Q

Increased BUN?

A 
• Dehydration 
• Reduced renal perfusion (congestive heart failure, hypovolemia)
• ↑ dietary protein
• Accelerated catabolism
(fever, trauma, GI bleeding) 
• Steroids 
• Tetracycline
63
Q

Decreased BUN?

A

• Over-hydration
• ↑ renal perfusion
(pregnancy, SIADH)
• Restriction of dietary protein/malnutrition
• Liver disease (impaired metabolism of ammonia to
urea)

64
Q

What is serum creatinine (Scr)

A

Normal 0.5-1.2 mg/dL

Product of muscle metabolism

A means of estimating GFR

65
Q

Serum creatinine is excreted by?

A

Glomerular filtration - 90-05%

Distal tubule - 5-10%

66
Q

Serum creatinine is increased by?

A 
• acute or chronic renal
failure 
• urinary tract obstruction 
• ↑ cooked meat intake 
• ↑ muscle mass 
• meds (i.e., cephalosporins, cimetidine, probenecid, &amp; trimethoprim)
       – +/- creatine supplementation
67
Q

Serum creatinine is decreased by?

A
  • vegetarian diet
  • ↓ muscle mass (small children, elderly)
  • drugs (i.e., methyldopa)
68
Q

Normal BUN: Creatinine ratio

A

10:1

69
Q

Increased/decreased creatinine ratio?

A

Increased: prerenal and postrenal azotemia
- dehydration

Decrease: intrinsic renal disease

70
Q

Homeostasis and GFR?

A

Homeostasis of body fluids requires kidneys to maintain relatively constant GFR

71
Q

GFR depends on?

A
  • Renal autoregulation
  • neural regulation
  • hormonal regulation
72
Q

Regulation mechanisms of GFR?

A

2 main mechanisms

  1. control of blood flow in and out of glomerulus
    - changing diameter of afferent and efferent arterioles
  2. Control of glomerular surface area
    - via contraction or relaxation of mesangial cells
73
Q

Most important parameter in clinical eval of renal function?

A

GFR

74
Q

Factors that affect GFR?

A

Body size
Age
Physiologic state
Race

Huge variations

75
Q

GFR is used to?

A

Adjust medications

76
Q

How is GFR measured?

A

Measuring the plasma concentration and excretion of a marker substance

  • Gold standard - injected inulin, measure
  • now its creatinine clearance
77
Q

Cockcroft and gault GFR?

A

Used to estimate GFR w/out 24-hr urine collection
- serum only

There is a formula slide 72

78
Q

Modification of diet in renal disease (MDRD)

A

New method to calculate GFR

Dont memorize it

79
Q

FE(na)

A

Fractional excretion of sodium
- Na excreted by body relative to amount filtered by kidneys
( na remaining in urine)

Most accurate when pt is oliguric

80
Q

What is FE(na) used for?

A

Suspected acute renal failure (ARF)

81
Q

How to calculate Fe(na)

A

Slide 76

82
Q

Determine the general cause of AFR?

A

Decreased perfusion

  • FE(na) <1%
  • hypovolemia, dehdration

Intrinsic renal disease
- FE(na) >1%

83
Q

How do you cook kidneys?

A

You boil the piss out of them!

Senior - GU Test 1 (13 decks)

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