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Urinalysis & Body Fluids > Physical & Chemical Examination of Urine > Flashcards

Physical & Chemical Examination of Urine Flashcards

1
Q

Why analyze urines?

A

fluid biopsy of kidney
noninvasive means to evaluate kidney
readily available
urine is ultrafiltrate of plasma

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2
Q

First morning specimen

A

most concentrated; often preferred specimen

most acidic- formed elements are better preserved

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3
Q

Random specimen

A

for routine screening

can be affected by excess fluid intake or exercise

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4
Q

Timed specimen

A

collections for predetermined length of time or at a specific time of day
primarily used for chemistry testing

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5
Q

Midstream ‘clean catch’

A

for bacterial cultures or to prevent vaginal contamination

begin urination into toilet, collect midstream portion in container, finish voiding in toilet

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6
Q

Catheterized specimen

A

requires collection by medical personnel

sterile catheter insterted through urethra into bladder

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7
Q

Suprapubic Aspiration

A

requires collection by medical personnel
involves puncturing of abdominal wall & distended bladder by using needle & syringe
normally sterile
used for cultures or in infants (anaerobic infections)

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8
Q

Pediatric collections

A

plastic urine collection bag attached to perineal skin

routine testing

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9
Q

Reasons for specimen rejection

A 
unlabeled/ mislabeled 
mismatch of specimen name with order
inappropriate collection technique
not properly preserved
time delay in receipt of specimen
visibly contaminated
insufficient volume
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10
Q

Containers

A

clean, dry, clear, sterile containers

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11
Q

preservation of samples

A

preserve specimen if not processed in 2 hours or more

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12
Q

pH change after 2 hours at RT

A

increased pH because of the break down of urea into ammonia by bacteria

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13
Q

glucose change after 2 hr at RT

A

decreased

glycolysis & bacterial utilization

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14
Q

ketone change after 2 hr at RT

A

decreased

volatilization of compounds

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15
Q

bilirubin change after 2 hr at RT

A

decreased

exposure to light

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16
Q

urobiliogen change after 2 hr at RT

A

decreased bc of oxidation to urobilin

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17
Q

nitrite change after 2 hr at RT

A

increased or decreased

bacterial reduction to nitrate or all the way to nitrogen gas

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18
Q

bacteria change after 2 hr at RT

A

increased

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19
Q

color change after 2 hr at RT

A

varying changes due to oxidation or reduction of metabolites

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20
Q

turbidity change after 2 hr at RT

A

increased bc bacterial growth & precipitation of amorphous material

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21
Q

sediment change after 2 hr at RT

A

disintegration bc of dilute alkaline urine

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22
Q

most common preservation technique for urines

A

REFRIGERATION!!

should not be used for routine testing if urine will be analyzed within 2 hr

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23
Q

other urine preservatives

A

10% formalin
thymol/toluol
boric acid
NaF

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24
Q

urine color

A

due to the presence of urochrome- by product of bilirubin

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25
Q

foam

A

not normally included on report forms
stable white foam indicates large amounts of albumin
yellow foam is increased bilirubin

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26
Q

causes of cloudiness

A

contamination from skin, vaginal secretions, bacterial growth or fecal material
precipitation of dissolved solutes, x-ray contrast media
RBCs, WBCs, clots, casts

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27
Q

normal daily volume

A

600-1800 ml/day

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28
Q

polyuria

A

> 3L per day of urine

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29
Q

oliguria

A

<400 mL per day

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30
Q

anuria

A

0 mL per day

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31
Q

nocturia

A

> 500 mL at night

highly suggestive of chronic progressive renal failure

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32
Q

odor

A

normally has aromatic odor

urine on standing becomes more odorous due to bacterial conversion of urea to ammonia

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33
Q

Specific gravity

A

an expression of concentration in terms of density: mass of solutes present per volume of solution
1.002-1.040
read via refractometry & reagent strip chemical method

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34
Q

3 factors that affect the refractive index of a solution

A

wavelength of light used
temperature of solution
concentration of solution

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35
Q

Specific Gravity strip test principle

A

indirect measurement
strip pad impregnated with a polyelectrolyte & a pH indicator at an alkaline pH
protons are released from polyelectrolyet in proportion to ionic concentration of the urine; released protons change pH of test pad

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36
Q

False decrease of Specific gravity test

A

high glucose & urea concentrations

pH >6.5

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37
Q

false increase of specific gravity test

A

high protein & ketoacids

X-RAY CONTRAST MEDIA - will make it so elevated that the urine will need to be diluted

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38
Q

pH of urine & clinical significance

A

4.5-8.0

precipitation of crystals, treatment of UTI, determination of poor specimen

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39
Q

pH principle

A

two indicators: METHYL RED & BROMTHYMOL BLUE

40
Q

Protein general

A

indicative of renal disease

normal excretion <150mg/day (threshold of dipstick)

41
Q

components of urine protein

A

albumin! -1/3
microglobulins
Tamm-Horsfall (uromodulin)- protein synthesized by distal convoluted tubule & in cast formation
proteins from fluids

42
Q

orthostatic proteinuria

A

excreting protein during the day/moving & not excreting while laying down/not moving

43
Q

pathological proteinurias

A

Multiple myeloma- bence jones
glomerular membrane damage
impaired tubular reabsorption
microabluminuria - DIABETIC PATIENTS; this will monitor kidney function

44
Q

transient proteinuria

A

benign, exercise, goes away after period of rest

45
Q

1 cause of acute glomerular nephritis

A

strep throat (group A strep)

46
Q

precipitation protein test

A

3% sulfosalicyclic acid (SSA)- equal parts SSA & urine supernatant

47
Q

false positives on SSA protein test

A

X-RAY CONTRAST MEDIA!

high doses of penicillin

48
Q

false negatives on SSA protein test

A

highly buffered (alkaline) urine

49
Q

Dipstick protein principle

A

colorimetric albumin test:
‘protein error of indicators’- pad w/ pH indicator
H+ combine with protein causing a color change

50
Q

false positives of dipstick protein

A 
highly alkaline (buffered) urine
urine in contact w/ strip for prolonged time
detergents
51
Q

false negatives of dipstick protein

A

protein other than albumin present

substances that mask color

52
Q

Microalbumin

A

routine test strips unable to detect albumin in urine that is <1-2 mg/dL
most often used in patients with diabetes to screen for kidney damage

53
Q

Glucose

A

used as a screening test for diabetes

renal threshold - 160 +/- 20 mg/dL

54
Q

classic picture of diabetic urine

A 
low pH
dilute
pale yellow
high specific gravity
high glucose
55
Q

high urine glucose & normal plasma glucose

A

pregnancy
emotional stress
diet high in COH

56
Q

dipstick glucose test

A

glucose oxidase- principle based on double sequential enzyme reaction that is specific for only glucose
glucose oxidase- oxidizes glucose for form H2O2
peroxidase- H2O2 to oxidized chromogen resulting in color change

57
Q

false positives of dipstick glucose

A 
oxidizing agents (ppl using bleached containers for their urine)
peroxidase contaminants
58
Q

Copper reduction test

A

detects all reducing sugars (sucrose only non reducing sugar)
clinitest- should be performed on all children to test for inability to metabolize galactose

59
Q

Ketones in urine

A

breakdown products from large amounts of fatty acids

diabetic ketoacidosis or excessive CHO loss - low CHO diet, vomiting, diarrhea, eating disorders

60
Q

ketone dipstick test

A

nitroprusside reaction

in alkaline medium, acetoacetate reacts with sodium nitroprusside in pad causing color change

61
Q

false positives for ketone dipstick

A

highly pigmented urine, free sulfhydral groups, levodopa metabolites

62
Q

false negatives for ketone dipstick

A

improper storage

ketone bodies are volatile & will evaporate

63
Q

hematuria clinical significance

A

whole RBC in urine
pre-renal
renal- glomerular nephritis
post renal- kidney stones

64
Q

hemoglobinuria clinical significance

A

lysed RBC in urine
exogenous- burns, trauma, drugs
endogenous - hemolytic anemias etc

65
Q

myoglobinuria clinical significance

A

muscle hemoglobin in urine
muscle wasting diseases
severe exercise

66
Q

blood dipstick test

A

‘heme’s pseudoperoxidase activity’

pad has chromogen & peroxide, pseudoperoxidase reduces peroxide & chromogen is oxidized causing color change

67
Q

tips for testing blood in urine

A

always ensure urines are well mixed as RBCs will settle out

RBCs lyse in an alkaline urine

68
Q

false positives for blood dipstick

A

oxidizing agents
microbial peroxidases
menstrual contamination

69
Q

false negatives for blood dipstick

A

ASCORBIC ACID, high specific gravity
captopril
RBCs settle out

70
Q

hematuria color, chemical & microscopic

A

red, smokey
positive dipstick
positive microscopic

71
Q

hemoglobinuria color, chemical & microscope

A

pink, red, brown & clear
positive dipstick
negative microscope

72
Q

myoglobinuria color, chemical & microscope

A

brown & clear
positive dipstick
negative microscope

73
Q

Solubility test

A

myoglobin is soluble in ammonium sulfide while hemoglobin is not
differentiates myglobinuria vs hemoglobinuria

74
Q

bilirubin production

A

prehepatic jaundice- hemolytic anemia & transfusion rxns
hepatic jaundice- hepatitis & cirrhosis
post hepatic jaundice- obstructive jaundice from stones or tumors

75
Q

prehepatic urine bilirubin & urobilinogen

A

urine bilirubin- negative

urine urobilinogen - increased

76
Q

hepatic urine bilirubin & urobilinogen

A

u. bilirubin- positive

u. urobilinogen- increased

77
Q

hepatic (unconj.) urine bilirubin & urobilinogen

A

u. bilirubin - negative

u. urobilinogen - normal or decreased

78
Q

post hepatic urine bilirubin & urobilinogen

A

u. bilirubin - positive

u. urobilingoen - negative!

79
Q

dipstick test for bilirubin

A

diazo reaction

bilirubin reacts with diazonium salt in pad to form azobilirubin which is brown

80
Q

false positives for dipstick bilirubin

A

drugs

urine pigments

81
Q

false negatives for dipstick bilirubin

A

ASCORBIC ACID
high nitrate
improper storage

82
Q

icotest

A

more sensitive test for bilirubin

washes away pigments in urine

83
Q

best specimen for urobilinogen

A

2 hr collection from 2-4 pm during ‘alkaline tide’

84
Q

urobilinogen dipstick principle

A

ehrlich’s reaction
P-dimethylaminobenzaldehyde: reacts with urobilinogen & porphobilinogen
can NOT detect a decreased urobilinogen

85
Q

false positives for urobilinogen

A

other ehrlich reactive compounds: atypical colors or substances that mask results

86
Q

false negatives for urobilinogen dipstick

A

formalin

improper storage

87
Q

Watson-Schwartz differentiation

A

urobilinogen is soluble in organic solvents (chloroform & butanol)
porphobilinogen is insoluble in organic solvents & stay in the urine

88
Q

nitrite intro & clinical significance

A 
rapid screen for UTI test
cystitis- bladder infection
pyelonephritis - kidney infection
evaluation of effectiveness of antibiotic therapy
screen for urine cultures
89
Q

nitrite dipstick test

A

diazotization reaction of nitrite with an aromatic amine in pad:
forms a diazonium salt which couuples with an aromatic compound in pad to produce azo dye
color change to white to pink

90
Q

false positives of nitrite test

A

increase in bilirubin or other pigment

improper storage

91
Q

false negatives of nitrite test

A 
ASCORBIC ACID
antibiotics
non-nitrate reducing bacteria
urine not in bladder long enough
urine does not contain nitrate
92
Q

Leukocytes intro & clinical significance

A

UTIs, cystitis or pyelonephritis

only picks up WBCs with esterases - NOT LYMPHS

93
Q

leukocyte dipstick test

A

principle based on action of leukocyte esterase to cleave an ester in pad

94
Q

false positives leukocyte dipstick

A

substances that induce color or mask results

vaginal contamination

95
Q

false negatives leukocyte dipstick

A 
high levels of glucose & protein
LYMPHS present 
high specific gravity
strong oxidizing reagents
drugs
96
Q

Ascorbic acid

A

interferes with : glucose, blood, bilirubin, nitrite & leukocytes

Urinalysis & Body Fluids (8 decks)

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