12b. Urinalysis: Chemical Evaluation Flashcards
How do we chemically examine urine?
eval is semi-quantitative when using reagent strips
strips have pads that are impregnated w/ chemicals - when urine is applied, color changes
Must adhere to expiry date of urine strips to avoid falst neg results
keep lid of container tightly sealed to prevent color changes due to enviro conditions - don’t tough pads with your fingers!
How should we use chemical strips?
must be stored at room temp
should be fully immersed (dipped) in the urine w/ excess being wicked away by tilting the long edge on a paper towel (can pipette sample on test strip but must make sure pads are fully saturated)
Strips can be for individual tests or for multiple tests
must read color change @ appropriate times
Which chemical strips test results have limited reliability?
leukocyte tests - verify on microscopic exam
specific gravity
urobilinogen
nitrates
How do we test for pH of urine?
must be fresh and at room temp for testing - pH tends to inc the longer the sample is sitting at room temp
Can be measures w/ dipstick or a pH meter - meter more accurate, however strip gives sufficient results
<7 is acidic, >7 is alkaline
What might influence pH?
depends on animals diet
Forage based = alkaline urine
High protein, cereal based = acidic
meast based = acidic urine
What is the normal pH of dogs and cats in health? What about herbivores?
Have normal pH of 6-7. pH of dog and cat urine tends to inc shortly after eating due to alkaline tide
herbivores have alkaline urine in health
Why is pH useful for sediments?
will help identify structures present in urine sediment
struvite crystals tend to form in alkaline urine
calcium oxalate, cysteine and uric acid calculi tend to form in acidic urine
How can we utilize the fact that diet affects pH?
prescription urinary diets to prevent the recurrence of stones and crystals by acidifying the urine
they work by having inc salt content to inc drinking and diluting urine
also minimize pH fluctuations during alkaline tide
What can cause an increase in urine pH?
urease-prod bacteria to become more alkaline - possible w/ bladder infection or if urine is sitting for extended periods at room temperature
Stress and excitement can cause an inc in urine pH
alkalosis
urine retention, and medications
What might reduce the pH of urine?
a fever, starvation, acidosis, excessive exercise, and medications
What is proteinuria
its an abnormal increase in quantity of protein in the urine
D/C normally have 0 to trace amounts of protein in urine, why might the collection method affect this?
The bladder is highly vascularized, so if you poke it multiple times, you may pierce the vessels and blood has protein in it so artificially rise the amount
How should the presence of proteinuria be interpreted?
Based on quantification, urine collection method, microscopic exam of urine and USG - dilute urine can give false neg results
What might cause proteinuria?
urinary tract hemorrhage or inflam, renal tubular degeneration, exercise, fever, or due to contaminants from the genital tract, trauma from urinary catheterization, manual expression or cystocentesis
What might cause palse positive protein tests?
the result of extremely alkaline urine samples