Lecture 5: Urinalysis Flashcards

1
Q

What are the 3 components of a complete urinalysis?

A
  1. Gross assessment
  2. Macroscopic/Dipstick analysis
  3. Urine microscopy
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2
Q

What are the components of a gross assessment for urine? What do they mean?

A
  1. Color
    Pink/Red/Brown = Blood, food, or medicine
    Orange/Red = Phenazopyridine
    Black = Hemoglobin, myoglobin, homogentisic acid
    White = WBCs
    Green/blue = Pseudomonas infection, urinary catheter
  2. Clarity
    Clear = normal
    Turbid = abnormal (crystals, sperm, proteins, cells)
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3
Q

What are components of dipstick analysis?

A

Specific gravity
pH
Leukocytes
Nitrite
Protein
Glucose
Ketones
Blood

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4
Q

What is specific gravity?

A

Specific gravity is the density of urine:distilled water (vol urine = vol water)

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5
Q

What does urine specific gravity tell us about a patient?

A

Tells us about the kidney’s concentrating ability

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6
Q

What is the range of specific gravity and what does the numbers mean?

A

Range: 1.003 (v. dilute) - 1.035 (v. concentrated)
Low SG (<1.010) = Increased fluid intake, diuretics, diabetes
High SG (>1.030) = Dehydration, decreased renal perfusion, syndrome of inappropriate ADH (siADH)
Fixed SG (1.010) = Severe renal disease with inability to concentrate or dilute urine

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7
Q

What is normal urine pH?

A

pH 4.5-8

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8
Q

What does pH tell us about a patient? Give 2 examples for acidic urine and 4 examples for alkaline urine.

A

Acidic:
1. High protein diet
2. Metabolic/respiratory acidosis

Alkaline:
1. Vegetarian diet
2. Metabolic/respiratory alkalosis
3. Renal tubular acidosis
4. UTI

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9
Q

What is leukocyte esterase?

A

Enzyme found in neutrophils and macrophages

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10
Q

What does leukocyte esterase tell us if found in the urine?

A

A positive test indicates:
1. Inflammation
2. Infection - confirm with culture
3. Malignancy
4. Stones
5. Glomerulonephritis

False negatives might occur due to
1. High urine protein/glucose
2. Positive Vit C

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11
Q

What does nitrite tell us when found in the urine?

A

UTI

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12
Q

What are the causes of false negatives and positives when measuring nitrite in urine?

A

False positive:
1. Bacterial contamination
2. Delayed analysis
3. Improperly stored dipstick strips

False negative:
1. Low nitrate diet
2. Insufficient urine dwell time in bladder
3. Antibiotic use
4. Certain urine bacteria don’t form nitrite

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13
Q

What is the normal range for protein in the urine?

A

<150 mg/day

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14
Q

What kind of protein does the urine dipstick detect?

A

Albumin
Cannot detect monoclonal Ig light chains for MM

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15
Q

What does a positive protein result mean in urine dipstick analysis?

A

Glomerular proteinuria

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16
Q

What is the grading of protein for urine dipstick analysis?

A

1+ = 200-500 mg/day
2+ = 0.5-1.5 g/day
3+ = 2-5 g/day
4+ = >7g/day

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17
Q

What are some cons that come with testing protein for urine dipstick analysis?

A
  1. Dependent on urine concentration
  2. Not sensitive enough to detect moderately increased albuminemia
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18
Q

Why would glucose be present in the urine? (2)

A
  1. Filtered glucose load exceeds the reabsorptive capacity of the renal tubule
  2. Defect in reabsorption of filtered glucose (plasma glucose lvl < 10 mM)
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19
Q

What are some errors that can come with glucose urine dipstick analysis?

A

May be false -ve with high levels of Vitamin C

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20
Q

Is ketones present in the urine normally?

A

No

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21
Q

Where do ketones come from?

A

Fatty acid metabolism

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22
Q

What are the possible causes of a positive urine dipstick analysis for ketone? (IMPT)

A
  1. Diabetes
  2. Starvation
  3. Alcoholic ketoacidosis
23
Q

How does the urine dipstick work in order to detect blood in the urine?

A

Dipstick detects peroxidase activity of RBC

24
Q

What does a positive urine dipstick analysis for blood suggest?

A

Presence of:
1. Hemoglobin - intravascular hemolysis
2. Myoglobin - rhabdomyolysis

25
Q

What is urine microscopy used for?

A
  1. Atypical samples
  2. Abnormal urine dipstick
26
Q

What are the steps of urine microscopy?

A
  1. Centrifuge
  2. Throw supernatant
  3. Examine under microscope
27
Q

What are the components found under urine microscopy?

A
  1. Casts
  2. Crystals
  3. Cells
  4. Organisms
28
Q

What does it mean when you find yeast in urine using urine microscopy?

A
  1. Sample contamination
  2. Yeast infection
29
Q

What does it mean when you find squamous epithelial cells in urine using urine microscopy?

A

Sample contamination

30
Q

What does it mean when you find neutrophils and bacteria in urine using urine microscopy?

A
  1. Infection
  2. Interstitial nephritis
  3. Glomerulonephritis
  4. Stones
  5. Sample contamination
31
Q

What does it mean when you find sperm in urine using urine microscopy?

A
  1. Normal for adult males
  2. Contamination for adult females
  3. Sexual abuse for children?
32
Q

What does it mean when you find transitional epithelial cells in urine using urine microscopy?

A
  1. Normal
  2. Inflammatory/malignant disease of urinary tract
33
Q

How are casts formed?

A

Formed from Tamm-Horsfall protein secreted by tubular cells and develop in the distal convoluted tubule/collecting ducts

34
Q

What are urinary casts made out of?

A
  1. Matrix
    Contains TAMM-HORSFALL MUCOPROTEINS produced by renal tubular cells in the thick ascending limb of the loop of Henle
  2. Trapped elements embedded in matrix
    This results in casts with different appearances
35
Q

What are the different types of urinary casts?

A

Fatty casts
RBC casts
Hyaline casts

36
Q

What do fatty casts indicate?

A
  1. Nephrotic syndrome
  2. Lipid storage diseases
37
Q

What do RBC casts indicate?

A
  1. Glomerulonephritis
  2. Acute Interstitial nephritis
38
Q

What do hyaline casts indicate?

A
  1. Normal
  2. Exercise
  3. Dehydration
  4. Fever
39
Q

What are urinary crystals?

A

Common crystals that form when urine is supersaturated with chemical constituents

40
Q

What are the factors affecting crystal formation?

A
  1. Concentration of constituents
  2. Hydration status
  3. Temperature
  4. pH
41
Q

What are the 3 types of crystals?

A
  1. Common crystals
  2. Pathological crystals
  3. Drug crystals
42
Q

What are common crystals made out of? What do they indicate?

A
  1. Uric acid
  2. Calcium oxalate - normal, ethylene glycol poisoning
  3. Triple phosphate crystals - Normal, UTI
43
Q

What are pathological crystals made out of? What do they indicate?

A
  1. Cholesterol - nephrotic syndrome, lipid storage disorder
  2. Cystine - cystinuria
  3. Bilirubin crystals
44
Q

What are significant findings of urine microscopy in respect to cells?

A
  1. > 3 RBCs / high power focus (HPF)
  2. > 5 WBCs / HPF
  3. > 2 renal tubular or transitional cells / HPF
45
Q

What are significant findings of urine microscopy in respect to casts?

A
  1. > 3 hyaline or granular casts / low power focus (LPF)
  2. Any WBC, RBC, or epithelial cast
  3. Any fatty cast
46
Q

What are significant findings of urine microscopy in respect to crystals?

A
  1. Any pathological crystal
  2. A lot of non-pathological crystals
47
Q

What are significant findings of urine microscopy in respect to organisms?

A
  1. > 10 bacteria/HPF in a fresh sample
  2. Any fungus/parasite
48
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of acute glomerulonephritis?

A

Gross: Smoky/turbid

Macroscopic: Blood/protein

Microscopy: RBC casts, RBCs, WBC casts, renal tubular epithelial cell casts, WBCs (sometimes), epithelial cells (sometimes)

49
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of nephrotic syndrome?

A

Gross: Frothy
Macroscopic: +++ protein
Microscopic: Fatty casts, cholesterol crystals, oval fat bodies

50
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of acute tubular necrosis?

A

Gross: Non-specific
Macroscopic: Fixed SG, mild protein, maybe blood
Microscopic: Renal tubular epithelial cell casts, epithelial cells

51
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of diabetes mellitus?

A

Gross: Non-specific
Macroscopic: Glucose, ketones (diabetic ketoacidosis), proteins (diabetic nephropathy)
Microscopic: Non-specific

52
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of end-stage renal disease?

A

Gross: various
Macroscopic: Fixed SG, maybe blood and/or proteins
Microscopic: Broad casts

53
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of acute pyelonephritis?

A

Gross: Turbid
Macroscopic: Nitrite, leukocyte esterase, mild protein
Microscopic: WBC casts, WBCs, bacteria, epithelial cells (maybe)

54
Q

What are the urine findings (gross assessment, macroscopic analysis, microscopic analysis) of lower UTI?

A

Gross: Turbid
Macroscopic analysis: Nitrite, leukocyte esterase, maybe blood
Microscopic analysis: WBCs, transitional epithelial cells, bacteria

NO CASTS