Renal Function Flashcards
USG <1.007
Hyposthenuria
Markedly decreased urine production
Oliguria
No urine produced
Anuria
Straining to urinate
Stranguria
Increased frequency of urination
Pollakiuria
Increased urea nitrogen with/without increased creatinine
Azotemia
Excessive urea in blood with clinical signs of renal failure
Uremia
T/F: with the loss of nephrons, unaffected nephrons will compensate by hypertrophy of function
True
Where is BUN synthesized?
Liver
Proteins form the small intestine -> amino acids –> deaminated in the liver –> amine group is used to make urea -> blood -> filtered by the glomeruli and excreted
What can cause the BUN concentration to vary?
Production by the liver
Reabsorption
- kidney
- GI tract
Excretion
Is BUN a good marker of kidney function in ruminants ? Why or why not?
Nope
BUN excretes into saliva and rumen
Rumen microflora create amino acid
Urea is lost in creation of proteins
Results in a net protein gain and BUN loss
Increased BUN due to liver production is usually due to?
Upper GI bleed (stomach or proximal duodenum)
How is BUN increased by the kidney?
Decreased GFR
Renal resorption varies with rate of flow through tubules
If flow through the renal tubules is flow, what will occur to the serum BUN?
Increased
If there is a fast flow rate through the renal tubules, what will occur to the serum BUN”?
Decreased
What can caused decreased production of BUN by the liver?
Decreased aa delivery to liver
- portosystemic shunt (PSS)
- decreased protein in the diet
Hepatic insufficiency (80% loss)
Intestinal loss of proteins
- monogastric species
- cattle (lost through microbiota and loss in saliva)
What problems associated with the kidney cause a decreased BUN?
Decreased water resorption in proximal convoluted tubules
- increased GFR
- increased tubular flow
Where is creatinine produced?
Endogenous muscle catabolism
- creative phosphate
(Proportional to muscle mass)
T/F: creatinine is NOT reabsorbed by the kidney and is an excellent indicator of GFR
True
Will an old cat with muscle wasting have high OR low creatinine levels
Lower
If CREA is increased, what does it imply?
Decrease in GFR
Possibly altered nephron function
The concentration of BUN is dependent on ..
A. Dietary protein
B. Liver function
C. Glomerular filtration rate
D. Body condition
A
B
C
Not body condition because that is creatinine
What renal biomarker is released into circulation by all nucleated cells and is freely filtered by the glomerulus ?
Symmetric demethylarginine
You will see an increase in symmetric dimethylarginine with ___% loss of renal tubular function
40
What is indicated if SDMA is increased but CREA is normal?
You must rule out all other causes of decreased GFR
For the kidney to concentrate and dilute urine, it requires ____% functional neurons
33
The function of the kidney to concentrate/dilute urine is depended on production/responsiveness to _________ and maintaining ___________
ADH (vasopressin)
Medullary hypertonicity
How is urine specific gravity measured?
Refractometer
The higher the urine specific gravity, the more ________ the urine
Concentrated
Lower limit of USG in active concentration of urine in cat ?
1.035
Lower limit of USG with ability to concentrate urine in a dog?
1.030
Lower limit of USG where equine and ruminants are still concentrating urine?
1.025
T/F: USG should always be interpreted with hydration status
True
Polyuria occurs with loss of ______% of functional renal mass
66
You get azotemia with ____% loss of nephrons
75
What is azotemia?
Retention of nitrogenous waste products in blood
Categorize the azotemia..
Increased BUN
Increased CREA
Increased USG
Pre-renal
What are your two most common DDx for pre-renal azotemia?
Dehydration (decrease renal blood flow)
Upper GI bleed (increased urea production )
What 3 renal analyses affected by decreased GFR
BUN
CREA
SDMA
T/F: persistently decreased blood flow will cause renal damage
True
An increased production of urea can be due to?
Upper GI bleed
Decreased rumen motility
Endogenous protein catabolism
Liver takes aa -> urea -> measured as BUN
What are pre-renal causes of increased creatinine
Increased muscle mass
Neonatal foals -> dysfunctional prevent clearance of fetal CREA
Define the azotemia…
Increased BUN
Increased CREA
Decreased USG
Renal azotemia
In renal azotemia, what happens to the serum phosphorus levels
Increased
What are the causes of renal azotemia?
Infectious Toxin Hypoxia Neoplasia Congenital Hydronephrosis
What infectious agents can cause renal damage
Pyelonephritits
Leptospirosis
What toxins can cause renal damage
Ethylene glycol Drugs Grape Asiatic lilies Melamine
T/F: an animal with azotemia and polyuria is NOT always in renal failure
True
What other conditions can appear like renal failure?
Hypercalcium
Diabetes insipidus
Endocrine: cortisol or glucose
Franconi syndrome
A post renal azotemia can be caused by?
Urolithiasis (castrated males)
Trauma
Feline lower urinary tract disease
Uroabdomen (urine leaks into peritoneal cavity
What is the most likely cause of this azotemia..
Patient has tacky mucus membranes
Increased BUN
Increased CREA
Increased USG
Increased PCV
Increased TP
Increased Alb
Pre-renal azotemia
-> dehydration
Define the azotemia
Increased BUN
Increased CREA
Low USG
Straining to urinate
Large turgid bladder
Post renal azotemia
USG is variable in these cases-> looks to signalment and PE findings
Will phosphorous be increased or decreased in renal azotemia
Hyperphosphatemia
-> when GFR drops below 25% of normal phosphorus excretion is impaired
Most animals with renal failure are _____calcemic
Normo
Early/mid stages of renal failure
What are the mechanisms by which hypocalcemia develops in renal azotemia
Decreased renal tubular Ca resorption
Decreased renal tubular production of vit D
Hyperphosphatemia -> mineral depot
What occurs to PTH in renal azotemia?
Hyperparathyroidism
-> hypocalcemia stimulates PTH production (mobilize Ca from bone)
In what species can you see hypercalcemia in renal azotemia?
Horse and cat
Usually chronic renal failure
What is the expected USG of a patient with hypercalcemia due to renal azotemia?
Hyposthenuric
Calcium interferes with ADH receptors
In cats and cattle, what will occur to the levels of potassium in renal azotemia?
Hypokalemia
Cats-> hypokalemic nephropathy
Hyperkalemia due to renal azotemia is caused by what mechanisms?
Oliguria/anuria (decreased excretion) -> end stage chronic renal failure or acute renal failure
Metabolic acidosis -> hydrogen ions move intracellularly and potassium moves extracellularly
In most cases of renal failure, what are the levels of sodium and chloride?
Normal
Chronic renal failure can sometimes cause hyponatremia and hypochloremia
Hyponatremia and hypochoremia are always a finding in _________
Uroabdomen
What is the mechanism by which you get metabolic acidosis in renal disese?
Increased urinary loss of bicarbonate
Decreased tubular secretion of H+
Production of sulfate and phosphates
- unmeasured anions
- increased anion gap
The UA dipstick is best at detecting what protein?
Albumin
What are causes of physiological pre-renal proteinuria?
Hypertension
Fever
Seizure
Strenuous exercise
What proteins can be increased in pre-renal proteinuria?
Hemoglobin
Myoglobin
Para-proteins (bence-jones)
Renal proteinuria can be due to what causes ?
Glomerulonephritis (damaged barrier)
- Ag-Ab
- amyloid
Tubular proteinuria
- acute renal disease
- fanconi’s syndrome
What would the urine protein : creatinine ratio be in a glomerulonephritis ?
UPCR > 1.0
If the UPCR is greater than 0.5 what is the cause of the proteinuria?
Tubular proteinuria
Acute renal disease
Fanconi’s syndrome
What is the only time you will see hypoalbuminemia?
Glomerular proteinuria
A secondary globmerulonephropathy can be due to???
Chronic infectious disease
Non-infectious inflammatory disease
Neoplasm
What is the pathogenesis of glomerulonephropathy?
Renal glomerular damage
-damage to podocytes (AgAb complex or amyloid deposits)
Podocyte retraction
Filtration of larger proteins
Albumin -> hypoalbuminemia
Antithrombin -> hypercoagulability
What is nephrotic syndrome?
Protein losing enteropathy that leads to abdominal effusion
- proteinuria
- hypoalbuminemia
- abdominal effusion
- hypercholesterolemia
- hypercoaguable state
Acute renal failure can have what etiologies?
Toxicant (eg lilies or ethylene glycol)
Renal ischemia
Infection (lepto)
What is this ?
Azotemia
Hyperkalemia
Acidemia
Oliguria/anuria
Proteinuria
Acute renal failure
What is the etilogy of chronic renal fialure in cats
Irreversible chronic interstitial fibrosis
Cat with..
Poor BCS
Dehydration
Polyuria
Hypertensive
Non-regenerative anemia Azotemia Hyperphosphatemia Hypokalemia Metabolic acidosis
Polyuria
Isosthenuria
Chronic renal failure
Abdominal effusion Serum electrolyte imbalances -azotemia (increased BUN) -hyperkalemia -hyponatremia -hypochloremia
Uroabdomen
(Hyperkalemia and hyponatremia due to urine on serosal surfaces -> sodium moves out of abdominal cavity and potassium diffuses into the GI)
