Introduction to Urinalysis Flashcards
1
Q
Primary functions of the urinary system
A
- Regulating plasma concentrations of Na+, K+, Cl-, Ca2+, and other ions
- Regulating blood volume and blood pressure
- Contributing to the stabilization of the blood pH
- Conserving valuable nutrients
- Eliminating organic wastes
- Synthesizing calcitriol
- Assisting the liver in detoxifying the blood and deaminating amino acids
2
Q
Which parts of the nephron are located w/in the cortex?
A
- Glomeruli (where filtration occurs)
- PCT
- DCT
3
Q
Which parts of the nephron are located w/in the medulla?
A
Renal pyramid (loops of Henle inside this) and sinus (w/ minor calyces that merge to form the major calyx)
4
Q
The medulla is ____ to the lumen
A
Hyperosmotic
5
Q
Function of the glomerulus
A
Responsible for the production of the filtrate; located at the proximal end of the proximal tubule
6
Q
Function of the proximal convoluted tubule
A
- Significantly reduces the volume of water in the filtrate by reabsorbing approximately 2/3
- Na+, Cl-, glucose, and amino acids are absorbed from filtrate
- Removes unfiltered proteins or drugs out of the blood
- Secretes H+
7
Q
Function of the descending limb of the Loop of Henle
A
- Passively removes water out of the lumen
- Permeable to urea
- Impermeable to Na+ and Cl-
8
Q
Function of the ascending limb of Loop of Henle
A
- Na+ and Cl- are actively moved out of the lumen
- Impermeable to water
- Permeable to urea
9
Q
Function of the distal convoluted tubule
A
In the presence of aldosterone, Na+ is actively transported out of the lumen (followed by water)
10
Q
Function of the collecting duct
A
Determines the final concentration of urine
11
Q
JGA senses decreases in __________ ______ and releases renin which stimulates the production of angiotensin II which in turn stimulates the adrenal cortex to secrete aldosterone
A
Na+; blood volume
12
Q
Aldosterone actively increases _____ ______ from the lumen of the distal convoluted tubule and collecting duct and thus ______ pulls water out of the lumen. _______ is secreted into the lumen.
A
Na+ absorption; passively; K+
13
Q
_______ in the heart sense a drop in blood pressure, increase in plasma osmolality, and/or exposure to aldosterone
A
Baroreceptors
14
Q
The ______ synthesizes ADH which is transported to the pituitary gland for storage before it is released into the bloodstream
A
Hypothalamus
15
Q
ADH causes changes in the epithelium of the _____ ______ _____ and _____ ______ that enhance the passive flow of water out of the lumen
A
DCT and CD
16
Q
Patient with decreased blood pressure will compensate by doing what?
A
Produce more aldosterone
17
Q
Three primary pigments found in the urine
A
- Urochrome
- Urobilin
- Uroerythrin
18
Q
This substance indirectly stimulates the production of aldosterone
A
Renin
19
Q
This is the primary source of yellow coloration and is produced at a constant rate; primarily responsible for urine coloration
A
Urochrome
20
Q
This is an orange-brown colored pigment formed by the oxidation of urobilinogen; commonly found in old urines
A
Urobilin
21
Q
This is a pink pigment that attaches to urates in the urine and gives amorphous urates a pinkish hue
A
Uroerythrin
22
Q
Yellow foam in urine is most commonly due to what?
A
Bilirubin
23
Q
White foam in urine is most commonly due to what?
A
Protein
24
Q
This is a drug used to reduce discomfort in UTIs, causing urine to be very orange and obscures chemical testing
A
Pyridium
25
What three things are reported on urine containing pyridium?
- Color
- Clarity
- Specific gravity (by refractometer)
26
What is the clarity of normal urine?
Clear
27
List some nonpathologic states of slight turbidity in clear urine
- Amorphous phosphates precipitate out in alkaline urine
- Amorphous urates, calcium oxalates, or uric acid precipitate out in acidic urine
- Carbonates
28
List some nonpathogenic states of cloudy specimens
- Squamous epis from improper collection
- Bacteria (improper storage allows them to grow)
- Sperm
- Talcum powder
- Vaginal creams
- Radiogrpahic contrast
- Fat or chyle (digested from lymph vessels)
29
List some pathologic states from cloudy urine
- Bacteria
- Yeast
- Fungi
- RBCs
- WSBCs
- Trichomonas
- Fecal contamination
30
Describe a clear urine
- No haziness
- Easy to read printed material
31
Describe a slightly cloudy urine
Printed material is readable
32
Describe a cloudy urine
Printed urine material may still be seen but it won't be readable
33
A ratio between the density of urine and the density of distilled water at the same temperature; a measure of the kidney's ability to maintain the body's water and chemical balance through reabsorption
Specific gravity
34
Specific gravity measures the amount of ____ \_\_\_\_; depends on the ____ and ____ of dissolved particles
Dissolved solids; mass; number
35
What is the principle of the refractometer?
Refractive index → ratio of the velocity of light through air is compared to the velocity of light through a solution
36
How do you correct the specific gravity in a refractometer for glucose?
For every gram of glucose/dL, subtract 0.004
37
How do you correct the specific gravity in a refractometer for protein?
For every gram of protein/dL, subtract 0.003
38
How can the [glucose] and [protein] be determined?
By the reagent strip
39
Why does using centrifuged or uncentrifuged urine not affect the specific gravity when using a refractometer?
B/c we're measuring dissolved substances
40
In measuring specific gravity by reagent strip, when urine pH is ≥7.0, add ____ to the strip reading if it's being read manually
0.005
41
Is there interference from glucose, protein, or radiographic dyes when measuring specific gravity by reagent strip?
NO
42
What is the specific gravity of the filtrate as it leaves the glomerulus?
1.010
43
Three factors that affect the refractive index of a solution
- Wavelength
- Temperature
- Concentration
44
This term is used to describe urine w/ a specific gravity of 1.010
Isosthenuria
45
This term is used to describe urine w/ a specific gravity of \< 1.010
Hyposthenuric
46
If urine is constantly \< 1.010 (hyposthenuric) what does this represent?
The kidney's inability to concentrate urine
- Diabetes insipidus
- Renal disease
47
This term is used to describe ruine w/ a specific gravity of \> 1.010
Hpersthenuric
48
If urine is constantly \> 1.010 (hypersthenuric) what does this represent?
- Adrenal insufficiency
- CHF
- Hepatic disease
- Dehydration
49
What is the physiological limit of specific gravity?
1.040
50
If urine has a specific gravity \< 1.003, what does this represent?
Probably diluted w/ water
51
What factors influence hypersthenuric specimens?
- Renal function
- State of hydration
- Volume of urine excreted
52
Low fluid intake = ____ specific gravity
High
53
High fluid intake = ____ specific gravity
Low
54
What factors could cause a specific gravity to be \> 1.035?
- Dehydration
- Diabetes mellitus
- CHF
- Radiographic contrast
55
If the specific gravity is \> 1.035, what should you do?
Make a 1:2 dilution w/ distilled water and multiply all digits to the right of hte decimal by your dilution factor
56
This is the measure of the concentration of dissolved particles in a solution expressed in osmoles of solute particles/kg of solvent
Osmolality
57
Osmolality only measures dissolved particles, thus _____ and ______ are not measured
Lipids and protein
58
Reference ranges for
- Specific gravity
- Urine color
- Urine volume
- Specific gravity: 1.003-1.030
- Color: colorless to yellow
- Volume: 600-2000 mL/day
59
Measurement of ____ is the most accurate method to determine solute concentration
Osmolality
60
Urine:serum osmolality ratio (U/S)
1.0-3.0
61
Factors that influence daily urine volume
- Fluid intake
- Fluid loss from non-renal sources (vomiting, dirrhea, sweating)
- Solute diuresis
- Variation in ADH secretion
62
This term is used when describing urine output \< 400mL/24 hours; decreased volume is due to excess water loss
Oliguria
63
This is known as the cessation of urine flow
Anuria
64
This term is used when describing an increased volume at night; caused by renal failure
Nocturia
65
This term is used when describing an increased daily urine volume; caused by diabetes mellitus/insipidus, medications, diuretic therapy, caffeine, and alcohol
Polyuria
66
List the proper criteria for a good specimen
1. Proper patient ID (name, location, physician, collection date, collection time, test requested)
2. Fresh collection (should be tested w/in 2 hours of collection)
3. If testing is delayed, urine should be refrigerated
67
What are the different types of collection techniques?
- Routine
- Clean Catch Midstream (CCMS)
- Catheterization
- Suprapubic aspiration
68
Routine collection
- Advantages
- Ease
- Good for screening (usually adequate for indicating a disease process)
69
Routine collection
- Disadvantages
Not ideal for reflex urine cultures
70
This technique requires no preparation
Routine
71
This technique is often used w/ random specimens
Clean catch midstream (CCMS)
72
CCMS collection
- Advantages
- W/ education, easy to collect
- Good specimen for urine culture and routine analysis
73
CCMS collection
- Disadvantages
- Noncompliance in collection technique
- Difficult for some patients
74
Catheterization collection
- Advantages
- Specimens good for urine cultures and routine analysis
- Urethral catheters enter the bladder
- Ureteral catheters enter either of the ureters and can provide information about each kidney independently
75
Catheterization collection
- Disadvantages
- Increases risk of UTIs
- Medical staff needed
- Discomfort for patients
76
This technique involves collecting urine directly from the bladder by puncturing hte abdominal wall w/ a needle and syringe; usually performed for bacterial cultures (esp. for anaerobic specimens)
Suprapubic aspiration
77
Suprapubic collection
- Advantages
Sterile
78
Suprapubic collection
- Disadvantages
Invasive
79
A sterile bag w/ an adhesive border is placed on the patient to collect the urine
Pediatric
80
Pediatric collection
- Advantages
- Least invasive technique to attain specimen from an infant
- Specimen is satisfactory for screening purposes
81
Pediatric collection
- Disadvantages
- Inappropriate for urineculture due to many opportunities for contamination
- Cumbersome
82
List the types of specimens
- Random
- First morning
- Fasting
- TImed
- Chain of custody
83
Random urine
- Advantages
- No preparation
- Anytime (usually daytime)
- Usually satisfactory for routine screening and many disease processes will still be found
84
Random urine
- Disadvantages
Variances in fluid intake and exercise can affect urine composition
85
First morning urine
- Advantages
- Ideal for testing specimens that require concentration and incubation such as nitrates, protein, and bacteria
- Confirmation of orthostatic proteinuria
- Formed elements (casts) more stable
- Cells have better morphology
- More epis for cytology studies
86
First morning urine
- Disadvantages
- Additional crystals may precipitate upon cooling
- More prep and the specimen must be preserved if not tested w/in 2 hours
87
In this type of collection, the goal is to eliminate metabolites from food ingested prior to the beginning of the fasting period; often used for glucose monitoring for patients w/ diabetes mellitus or gestational diabetes
Fasting urine
88
This type of urine requires the patient to void immediately before eating and the collect urine 2 hours post eating; used for diabetes mellitus monitoring
2 hour postprandial
89
Any urine that is collected during a specific time frame w/in a 24 hour period
Fractional urine
90
this type of urine collection is used because of circadian and diurnal variations in hormones, proteins, glomerular filtration rates, exercise, hydration, etc; usually 12 or 24 hour collection; preservative is usually in the bottle before patient takes it home
Timed urine
91
Timed urine
- Disadvantage
- Preservatives and/or refrigeration may be required
- Many errors due to handling problems, storage problems, loss of a specimen, two morning specimens, etc
92
When measuring a urine's specific gravity using a reagent dipstick, are you required to correct for elevated urine glucose?
NO! The reagent strip is not affected by elevated glucose levels
93
Color will ____ w/ time
Darken
94
Clarity ____ due to bacterial growth and ____ of ____ materials
Decrease; precipitation; amorphous
95
pH ____ due to decomposition of urea to NH3 and loss of CO2 as a specimen is allowed to sit out, unpreserved
Increases
96
Glucose ____ due to bacterial consumption as a urine is allowed to sit out, unpreserved
Decreases
97
Ketones ____ due to bacterial action and will vaporize as a urine is allowed to sit out, unpreserved
Decreases
98
Bilirubin ____ due to photo-oxidation as a urine is allowed to sit out, unpreserved
Decreases
99
Urobilinogen ____ due to oxidation to urobilin as a urine is allowed to sit out, unpreserved
Decreases
100
Nitrites are ____ due to bacterial production as a urine is allowed to sit out, unpreserved
Increased
101
Nitrites are ____ due to conversion of nitrite to nitrogen gas as a urine is allowed to sit out, unpreserved
Decreased
102
RBCs, WBCs, and casts ____ as a urine is allowed to sit out, unpreserved
Degrade
103
Bacteria ____ as a urine is allowed to sit out, unpreserved
Increase
104
What is the most common method of preservation?
- Refrigeration at 4-6°C
\*\*REMEMBER: allow urine to reach room temp before testing!
105
Advantages of refrigerating urine specimens
- Easy
- Prevents bacterial proliferation (culture is still possible up to 24 hours)
- Does not interfere w/ most analytes
106
Disadvantages of refrigerating urine specimens
- Precipitation of amorphous urates, and phosphate crystals that interfere w/ microscopic analysis
107
Culture of a refrigerated specimen is preferred in ___ hours but will be accepted up to ___ hours
8 hours; 24 hours
108
Culture on an UNREFRIGERATED specimen must be performed within ___ hours post collection
2 hours
109
Commonly used preservative for 24 hours urine collections
Boric acid
110
Advantages of using boric acid as a preservative
- Preserves proteins and formed elements
- Bacteriostatic so specimen can be used for collection
111
Disadvantages of using boric acid as a preservative
- Precipitates out many crystals
- ↓ pH - Interferes w/ drug and hormone analysis
112
Advantages of using formalin as a preservative
Excellent cell preservative
113
Disadvantages of using formalin as a preservative
Interferes w/ glucose, blood, leukocyte esterase, and copper reduction testing (clinitest)
114
Advantages of mucolexx as a preservative
Preserves sediments such as cells and casts
115
Advantages of toluene as a preservative
- Does not interfere w/ most chemistry tests
- Prevents contamination by airborne bacteria
116
Disadvantages of toluene as a preservative
- Does not prevent the proliferation of bacteria already in the specimen
- Floats on the surface of the specimen and clings to pipettes, testing strips, etc.
117
What should you do if a urine culture is ordered, or is expected to be ordered?
Pour off the specimen for the urine culture before dipping or pipetting
118
Fresh and intact RBCs (hematuria) cause urine color to be what?
Pink → red
119
How does hemoglobin and myoglobin appear in the urine?
Urine is clear, reagent strip is positive for blood
120
\_\_\_\_ in the urine is often accompanied by a reddish plasma
Hemoglobin
121
\_\_\_\_ in the urine is often accompanied by a clear plasma b/c it's cleared from the blood quicker
Myoglobin
122
An accumulation of uroporphyrin causing port wine colored urine, color may be red but the strip may read negative
Porphyria cutanea tarda
123
Accumulation of coproporphrinogen, red or colorless urine w/ fluorescence
Lead poisoning
124
Brown, dark brown, or black urine can be caused by what three things?
- Melanuria (melanin in the urine)
- Alkaptonuria (homogenistic acid)
- Medications
125
Blue and green urine is caused by what three things?
- Biliverdin (an oxidized form of bilirubin)
- Bacterial infections (Pseudomonas)
- Medications
126
Pale yellow or colorless urine
- Nonpathologic states
?
127
Pale yellow or colorless urine
- Pathologic states
?
128
Dark yellow/amber/orange urine
- Nonpathologic states
?
129
Dark yellow/amber/orange urine
- Pathologic states
?
130
Red urine
- Nonpathologic states
- Menstrual contamination
- Pigmented foods (beets, blackberries)
- Medications
131
Red urine
- Pathologic states
?
132
Brown/dark brown/black urine
- Nonpathologic states
?
133
Brown/dark brown/black urine
- Pathologic states
?
134
Blue and green urine
- Nonpathologic states
?
135
Blue and green urine
- Pathologic states
?
136
List some causes of red urine
- Kidney stones
- Lower urinary bleeds
- Muscle injury
- Rhabdomyolysis
- Porphyria cutanea tarda
- Lead poisoning
137
What are the three main parts when examining urine?
- Physical characteristics
- Chemical characteristics
- Microscopic elements
138
Reference range for urine osmolality
275-900 mOsm/kg
139
What is A?
Medulla
140
What is M?
Cortex
141
What is L?
Renal pyramid
142
What is J?
Minor calyx
143
What is I?
Major calyx
144
What is H?
Renal lobe
145
What is E?
Renal papilla
146
What is D?
Ureter
147
What is B?
Renal pelvis
148
Urine is an ultrafiltrate of what?
Plasma
149
The process solely responsible for water reabsorption throughout the entire nephron is ____ \_\_\_\_
Passive transport
