Urinary System Flashcards
What is acute kidney injury?
A rapid loss in kidney function
A sudden reduction in GFR
Medical emergency- inability to maintain fluid, acid base and electrolyte balance
What is CKD?
Chronic kidney disease- structural or functional abnormalities of one or both kidneys that have been there for 3 months or longer
What does the GFR show?
Shows the total filtration of functioning nephrons
Best wat to asses kidney function
What is the gold standard of assessing kidney function’?
Clearance of exogenous filtration marker
What is clearance of a solute and what is the total body clearance equal to?
Clearance of suture is the rate at which the drug disappears from the body by excretion and/or metabolism
Body clearance- renal, hepatic and lung clearence
If a drug is not metabolised elsewhere and filtered freely and not reabsorbed what does this show?
Renal clearance= GFR
What is the units and equation of renal clearance?
mls/min
[B] in urine x urine flow
_________________
[B] plasma
What are the idealistic features of filtration markers?
Not metabolised anywhere else in the body
Freely filtered in glomerular capillaries
Not reabsorbed or secreted anywhere
Exogenous
What is the gold standard of GFR filtration markers?
Inulin
What can be used for GFR estimates that are cheap and readily accessible?
Urea- catabolism of deamination of amino acids
Creatine- steady breakdown of creatine phosphate in skeletal muscle
Why is Urea not an ideal measure of GFR?
Urea is partially fat soluble and so reabsorption occurs in the PCT
If GFR is decreased there is more time for reabsorption of urea
Normal continuous high filtration rate prevents excessive high conc of urea in the blood
What is urea production influenced by?
High urea- high protein diet, recent meal, catabolism, GI haemorrhage, dehydration
Low- sever liver disease, low protein diet, aggressive fluid therapy
Why is creatinine a useful measure of GFR?
Freely filtered, not reabsorbed or secreted
Endogenous but steady state
What is the problem of creatinine for measure go GFR?
Up to 75% of kidney function can be lost before serum increases
What are the three broad causes of decreases GFR?
Pre-renal
Renal
Post-renal
What causes pre-renal azotaemia?
Reduced blood supply to the kidney
What causes renal disease?
Intrinsic disease of the kidney
What causes post-renal disease?
Blockage of urine flow below the kidneys- bladder rupture
How can pre-renal and renal disease be distinguished?
Prerenal is occurring upstream of the kidney therefore animal can concentrate urine
Renal is kidney problem so the animal cannot concentrate urine
Would you expect hypovolaemic animals to have low urine specific gravity or high urine specific gravity?
Animals with hypovolaemia should be conserving volume therefore concentrating filtrate and have a high urine specific gravity
What are clinical signs of reduced renal function?
Anorexia and weight loss Dullness and lethargy PUPD Dehydration Vomiting Constipation Poor hair coat Signs related to hypertension