Urinalysis Flashcards
1
Q
“clean-catch” urine sample definition
A
- sample of urine collected midstream
- clean urethral area
- after some urine falls into toilet bowl, clear container is used to catch 1-2 oz
2
Q
Main methods of urine collection (5)
A
- random collection = no precautions to contamination
- early morning collection = sample before ingesting fluid (usually hypertonic)
- clean-catch = midstream urine specimen
- catheterization = usually comatose/confused pts
- suprapubic needle aspiration = purest sample; often in infants/small children
3
Q
Major types of urinalysis (5)
A
- macroscopic exam
- chemical analysis (urine dipstick)
- microscopic exam
- culture
- cytological examination
4
Q
Macroscopic characteristics of normal urine
A
- color = pale ==> dark yellow/amber
- clear (i.e. not cloudy)
- normal volume = 750 - 2000 ml/24hr
5
Q
Abnormal urine odors
A
- Ammonia-like: (Urea-splitting bacteria)
- Foul, offensive: Old specimen, pus or inflammation
- Sweet: Glucose
- Fruity: Ketones
- Maple syrup-like: (Maple Syrup Urine Disease)
6
Q
Abnormal urine colors
A
- Colorless: Diluted urine
- Deep Yellow: Concentrated Urine, Riboflavin
- Yellow-Green: Bilirubin / Biliverdin
- Red: Blood / Hemoglobin
- Brownish-red: Acidified Blood (Acute GN)
- Brownish-black: Homogentisic acid (Melanin)
7
Q
Abnormal turbidity on macroscopic exam
A
- Typically cells or crystals.
- Cellular elements and bacteria will clear by centrifugation.
- Crystals dissolved by a variety of methods.
- Microscopic examination will determine which is present.
8
Q
Chemical urinalysis: Glucose
A
- normal glucose <0.1% of that filtered by glomerulus = < 130mg/24hr
- glycosuria = (usually) diabetes mellitus
- strip = glucose oxidase + peroxide + potassium iodide + blue dye
- O2 produced by enzymes reacts w/blue to change color
- compare w/chart to see ~amount
- false-negatives in pregnant women
9
Q
Chemical urinalysis: Bilirubin
A
- bilirubin + diazotized dicholoraniline ==> tan colors
- false +: indican
- false -: ascorbate
10
Q
Chemical urinalysis: ketones
A
- diabetic ketosis or calorie deprivation ==> ketones
- ketone + nitroprusside ==> color change
- pink (negative) ==> purple (positive)
11
Q
Chemical urinalysis: specific gravity
A
- = weight of urine/weight of same volume of pure water
- test measures tubular fxn
- SG ~ density of urine ==> measures ability of kidney to concentrate/dilute
- ~SG via measuring pKa change in relation to ionic concentration of urine
12
Q
Chemical urinalysis: blood
A
- pseudoperoxidase rxn = more senstivie to hemoglobin and myoglobin vs. RBCs
- positive test = myoglobinuria, hemoglobinuria, or hematuria(=most common)
13
Q
Hematuria vs. Hemoglobinuria
A
- both ==> positive occult blood test on strip
- hematuria ==> red, cloudy urine that clears when centrifuged
- microscope: RBCs
- hemoglobinuria ==> reddish-brown urine that doesn’t clear after centrifugation
- microscope: no RBCs
14
Q
Chemical analysis: pH
A
- Urine normal pH ~ 6 (range 4.5 - 8.0)
- acidic urine = metabolic acidosis, high protein diet
- alkaline urine = renal tubular acidosis
15
Q
Chemical analysis: protein
A
- most strips detect albumin using indicator dye Bromphenol blue
- 1+ = ~200-500mg/24hr
- 2+ = ~.5-1.5g/24hr
- 3+ = ~2-5g/24hr
- 4+ = 7g/24hr
