exam 1 Flashcards
Shield of negativity
An electric field (podocyte) the prevents small poalr proteins from passing through the glomurerleous
Diabetes Mellitus
^ specific gravity
v insulin
v function of insulin
^ glucose
Diabetes insipidus
v specific gravity
v function/production of ADH
Urine to serum osmolality
1:1
Controlled hydration increases to 3:1 for testing
Fix high specific gravity
dilute 1:2 with distilled water (saline has stuff in it and would give false results for specific gravity)
Multiple the last 2 digits by the dilution factor eg: 2x 1.010 = 1.020
Color
Normal
Urochrome: normal
Uroerythrin: Pink sediment. high salt diet
Urobilin: Oxidation of urobilinogen
Color
Orange
Bilirubin: bile duct obstruction or liver disease
Pyridium: Drug for UTIs. shake test looks like bilirubin (needs ictotest)
easy bilirubin test
Shake and look for yellow foam. Can be mistaken for pyridium.
Color
Yellow-green
Photo-oxidation of products of bilirubin
biliverdin
Color
Red/pink/brown
Blood
Methemoglobin
Myoglobin
hemoglobin
Porphyrins/Porphobilinogen
Non-pathogenic: menstruation/food/medication
is it blood/hemoglobin/myoglobin?
Blood: Readand cloudy urine
Myoglobin: Clear plasma after spinning down
Hemoglobin: Red plasma after spinning down
Color
Brown/Black
Melanin: oxidation of melanogen
Homogentisic acid: Phenylalanine metabolite. Alkaptonuria
Medication
Color
Blue/green and purple
Green/ green-blue: Pseudomonas
Blue-indican: intestinal tract infections
Purple: Klebsiella. Catheterized patients can make a purple bag
Colo
Green
Medications
Chlorets
Oxidations products of IV medications
Pyridium Vs Bilirubin
Pyridium: Yellow foam with negative ictotest
Bilirubin: yellow foam with positive ictotest
Turbidity
nonpathogenic
Epithelial cells
Crystals
Semen
Radio contrast media
Talcum powder
Medications
Turbidity pathogenic
RBCs, WBC, Bacteria
Yeast
Non-squamous epithelial cells
abnormal crystals
lipids
Specific gravity
First renal function to become impaired: reabsorption process
Presumptive determination
Urometers measures at 20C
Standard is 1.010
Specific gravity averages
normal: 1.002 - 1.035
random specimen range: 1.015 - 1.025
Specimins <1.002 = bad sample (diluted or intentionally tampered with)
Specific gravity >1.035
Rediographic contrast media
Plasma expanders (dextran
Odor
Ammonia = Bacteria breaking down urea
Diabetic ketones = sweet
bacteria and yeast = foul odor
maple syrup urine disease = obvious
PKU = mousy odor
Renin-angiotensin-aldosterone
For sodium and fluid retention
BP V -> Renin released -> Angiotensin released -> vasoconstriction of afferent ducts -> aldosterone for Na reabsorption and fluid retenion -> BP goes up locally
Light and time effect on urine
Color: modified - oxidation
Clarity: decreased - bacterial growth and precip of crystals
odor: increased - bacterial growth
pH: increased - breakdown of ammonia by bacteria and loss of CO2
Glucose: decreased - bacterial growth
ketones: decreased - volitalization/bacterial growth
bilirubin: decreased - oxidation by light
Urobilinogen: decreased - oxidation to urobilin
nitrite: increased - nitrate reducing bacteria
RBC/WBC: decreased - disintegration in alkaline urine
Bacteria: increase - multiplication
Protein confirmation test
SSA
protein strip false positive
Alkaline urine
Test strip
pH
Acidosis/alkalosis
defects of renal function
Identification of crystals
renal calculi formation
Fluctuation due to diet mostly
methyl red : 4-6
bromthymol blue: 6-9
test strip
Protein
most indicative of renal disease
Albumin principle protein
Needs constant pH
Protein accepts H+ from strip, changes color
Interfered with: highly alkaline urine. causes false positive
SSA Confirmatory testing if pH >7.5 AND protein is positive
test strip
protein false positive and negatives
False Positives:
pigmented urine
ammonia compounds
high specific graviy
false negatives:
proteins other than albumin (Ig’s etc)
Microalbumin
Small amounts of albumin in urine. too little to detect
indicator of renal trouble.
detected with immunochemical assays/dye binding assays
microalbumin vs creatinine
Creatinine is usually stable. Albumin fluctuates with hydration
A:C normal: <30mg A:1g C
Microalbuminuria: 30-300mg A: 1g C
Clinical albuminuria: >300mg A: 1g C
Clinitest
We don’t use this anymore (part of the newborn screening tests)
Copper reduction test. generats a lot of heat. watch for passthrough (will go positive quickly, then return to baseline)
clinically significant RBCs in urine
5 RBC/uL
Strip test
Blood
Pseudoperoxidase activity
first spots turn splotchy for RBC activity
False positive:
Strong oxidizing detergents
Vegetable peroxidases
Bacterial peroxidases (requires microscopic confirmation)
False negatives:
Ascobic acid
Formalin, unmixed sample
urine rejection criteria
Improper labeling
Timing
transport (greater than 2hs)
quantity
24 hour collection
Void and flush at 8 am -> collect everything for 24 hours -> 8 am collect final sample and submit for testing
Done for creatinine clearance since it can fluctuate over 24 hours.
Loop of henle
Decending loop: Permeable to water. water is reabsorbed here
Ascending loop: impermeable to water. Ions are reabsorbed here
urine constituents
95% water, 5% soluted
1/2 of solutes is urea
Major organics: creatinine, uric acid.
Minor organic: hippuric acid
Major inorganic: chloride/sodium/potasium
Also hormones, vitamins, formed elements (crystals, cells, yeast, bacteria, casts, etc) and medications
determine if it’s urine
Urea and creatinine tests. higher concentrations in urine
Strip test
Bilirubin
Diazo rxn
Azodye (hidden by azo medication)
Ehrlich’s reagent
Urobilinogen test (tube)
Positive for prophobilinogen.
strip test
Nitrite
Tests for Nitrate reducing bacteria
Rapid screening test for a UTI
First morning specimen prefered (bacteria need time to reduce)
All meat diet might not have enough nitrates
False Negatives:
non-nitrate reducing bacteria (yeasts, GP organisms)
Too much bacteria reduces the nitrites to gas
False positive:
Sample isn’t fresh
Color interference
strip test
Leukocyte esterase
Tests for granulocytic WBCs
detects lysed WBCs. Use in conjunction with nitrite test.
False Pos:
Formalin
Pigmented urine
False Neg:
high protein and glucose
Ascorbic acid
crenated WBCs
Antibiotics
