urine analysis Flashcards
List the things looked at in a urine analysis
appearance chemistry Urine sediment infectious organisms Crystals
specific gravity range and why its tested
healthy kidneys
mid-range 1.30
high 1.50
when well hydrated can be 1.015
diseased kidneys that loose the ability to concentrate urine = dilute (1.008 - 1.015) in large quantities Polyuria and polydipsia
List diferent clearances that can be tested
GFR SDMA Inulin renal clearance creatinine clearance
GFR range
GFR of beagles and other breeds in literature cary from 1.5-4mls
GFR for cats appears to be lower than for dogs, but still cary in range from 1-3.8ml/kg/min
what is the filtration fraction (ff)
fraction of plasma that becomes glomerular filtrate
GFR/RPF = 20%
Explain Inulin clearance
Inulin = group of naturally occurring polysaccharides
filtered in the GFR as freely as water, its not absorbed or secreted
therefore by injecting Inulin into the plasma the excretion rate will be revealed
explain renal clearance
the volume of plasma completely cleared of a substance by the kidneys per unit time
this is measuring the rate not the volume that is cleared
renal clearance is used to estimate GFR
renal clearance formula
(concentration of x in the urine X rate of urine formation)/concentration of x in the plasma
explain Urea clearance
not as sensitive as creatine as urea is has some of it recycled in the body, therefore not as sensitive as creatinine
SDMA
serum SDMA (symmetric dimethylarginine) concentration like creatinine are inversely proportional to GFR an may move out of reference range before the serum creatinine concentration rise.
increased SDMA therefore may detect early renal disease in blood before azotemia develops
however not 100%, should be used with other tests like creatine and clinical signs
it is not 100% as these levels fluctuate day by day, and can be changed due to factors such as hydration, diet, toxic ingestion or medication use.
Urine protein/Creatine (UPC) ratio
protein in the urine can occur due to damage to the glomerulus or the tubules causing protein to leak into the filtrate
the issue is when there is more plasma protein then creatine which is usually secreted.
using the ratio ups normalises urine protein levels for variability in urine concentration
explain creatinine clearance
Used in clinical assessment of GFR to assess disease state
Creatinine is the breakdown product of creatine phosphate in muscle
Creatine freely filtered by glomerulus but is also secreted so not entirely accurate
as CR is byproduct of muscle mass, level of activity, or an event that may affect muscle metabolism
plasma creatinine levels are inversely proportional to GFR
If the GFR falls Kidney with excrete less creatine which means it is accumulating in the blood
therefore an increase of creatinein the body may indicate there is something wrong with the kidneys
explain the metabolism of digested protein
liver produces urea as a waste product of digestion of protein
it is excreted by kidneys
Causes of an increase in BUN include
high protein diet Increased catabolism Dehydration Congested heart failure fever decreased in GFR = suggestive of kidney failure
Important = BUN not the same a urea concentration in the blood but they are equivalent to one another
Azoteaemia
Increased BUN and/or creatinine in the blood (Note that some sources say both have to be elevated to indicate azotaemia)
we look at thus as as primary measure of kidney function in blood tests as elevation of BUN and creatinine indicates reduced clearance by kidneys (decreased GFR) does not indicate kidney disease.
however, reduced GFP does not always indicate kidney disease
causes can be
- prerenal - hypovolaemia/dehydratioj
-renal - kidney dysfunction
post renal - urinary calculi causing blocking
