Laboratory diagnosis of urinary disease Flashcards
Define uremia
complex of CS and biochemical abnormalities (azotaemia) associated with loss of functional nephrons (i.e. azotemia + CS)
CS - uremia
- anorexia
- V/D
- GI haemorrhage
- ulcerative stomatitis
- bruxism (ruminants)
Define renal disease
presence of morphological or biochemical abnormalities of any size/ severity
Define renal failure
biochemical abnormalities present and caused by reduced renal function, coupled with inadequate concentrating ability. Decrease in renal function is teh result of decrease in numbers of functions nephrons (vs decreased function in individual nephrons)
Clinical pathology - renal disease
BEFORE TX! biochem UA haematology cytology
What is important on routine biochem?
- UN
- creatinine
- phosphorous
- calciium
- sodium
- chloride
- potassium
- acid base
- protein
T/F: you need to look at serum/plasma chemistry and urine concurrently
True
What are indicators of GFR?
urea and creatinine levels (increases assess presence of renal dz/functional impairment)
Where is urea derived from?
produced in liver via urea cycle and excreted by kidney - levels influenced by liver function and protein levels
Where is creatinine derived from?
from creatine in muscle - levels influence by mm mass
What is UN synthesised from?
from ammonia (waste from protein catabolism) via urea cycle in liver
What are urea levels influenced by?
- protein intake
- GIT bleeding
Is UN excreted in faeces?
No
How long does it take for UN to equilibrate in vasculature?
90 minutes
Cattle can have severe renal dz with relatively normal UN
True
What is a reliable indicator of renal dz in ruminants?
Creatinine - not urea
Where is urea excreted in ruminants?
into rumen and converted to ammonia then aa –> protein synthesis
T/F: if a ruminant is anorectic all urea will be exreted via the GIT and not the kidneys so anorectic ruminants with renal faulure may have va normal UN
True
Describe urea and the kidney
- passively filtered by glomerulus (concentration in filtrate same as blood)
- increased UN largely d/t decreased filtration rate
- passively diffuses with water from lumen to blood
- urea absorbed varies inversely with rate of urine flow
T/F: cattle can have severe renal dz with relatively normal UN
True
Origin - creatinine
from non-enzymatic conversion of creatine (energy stores in mm)
- constant rate of conversion of creatine to creatinine
- influenced by mm mass (increases with training) and dz
Describe creatinine distribution through body
distributed through ttal body water but diffuses more slowly than urea
- equilibration takes 4 hours (vs 1.5 hours for urea)
Findings suggestive of ruptured bladder (clinical pathology)
- abdominal fluid concentrations of creatinine higher than serum levels
- difference with serum levels lasts longer than urea
- comparison of serum and abdominal fluid levels more reliable than urea
What is creatinine affected by?
not by diet or catabolic factors
What is the sensitivity of creatinine for diagnosing renal dz?
poorly sensitive - 3/4 renal function must be lost (dogs)
In which spp is creatinine a more sensitive indicator of renal dz?
cow and horse
Why is creatinine a v insensitive diagnostic test in birds?
-