Urinalysis

Question 1

What are the features of a complete urinalysis?

Answer 1

1. appearance - colour e.g. red in beets, brown in methemoglobin
2. specific gravity
3. chemical tests
4. microscopy

Question 2

What can be seen on microscopy?

Answer 2

1. crystals
2. cells
3. casts
4. organsisms

Question 3

Describe specimen collection and handling?

Answer 3

1. a clean-catch midstream urine is preferred
   - can catheterize in some cases to collect a clean sample
2. dont collect from a urine catheter bag
3. brief period refrigeration is acceptable
   - bacteria multiply at room temperature

Question 4

What is specific gravity?

Answer 4

ratio of weight of fluid vs equivalent volume of distilled water - normally around 1.010
- elevated in presence of protein, glucose or radiocontrast media in urine

Question 5

What is a urine dipstick?

Answer 5

a plastic strip with paper tabs impregnated with chemical reagents

Question 6

What can a urine dipstick test for?

Answer 6

1. pH
2. ketones
3. urobilinogen
4. bilirubin
5. nitrate
6. protein
7. blood
8. glucose
9. leucocytes

Question 7

pH?

Answer 7

normal 4.5 to 8

Question 8

Ketones?

Answer 8

detect acetoacetate and acetone and not beta-hydroxybutyrate
- false positive when patient is on captopril or levodopa

Question 9

Bilirubin?

Answer 9

conjugated bilirubin can be present in urine
- false patients on chlorpromazine

Question 10

Nitrate?

Answer 10

• screens for bacteriuria especially in gram negative bacteria which produce nitrite
• urine has to be in the bladder at least 4 hours to detect nitrites
• false negative in enterococcus since they dont produce nitrite

Question 11

Protein?

Answer 11

scored from trace to 4+
1+ = 20mg/dl
2+ = 30mg/dl
3+ = 300mg/dl
4+ = >2000mg/dl
- strips are sensitive to albumin but not globulins, hemoglobin and light chains or microalbuminuria

Question 12

Blood?

Answer 12

picks free Hb
- false positive with myoglobin, povidone iodine
- myoglobinuria and hemoglobinuria show positive dipsticks but negative microscopy

Question 13

Leucocytes?

Answer 13

test threshold is 5 to 15 WBCs/HPF

Question 14

Microscopy cellular elements?

RBCs vs WBSs?

Answer 14

1. erythrocytes
   - >2 to RBCs/HPF is pathologic
   - those from the renal parenchyma are dysmorphic
   - important if dysmorphic cells are >30%
2. leucocytes
   - polymorphonuclear (PMN) cells indicate urinary tract inflammation
   - may occur in GN or interstitial nephritis

Question 15

Casts?

Answer 15

1. hyaline - are nonspecific
2. granular - are usually pathologic and may occur in ATN, GN
3. red cell casts - are a hallmark of GN
4. WBC casts - show UTI