Renal Chemistry (chem lect 5, 6) Flashcards
Function of Urinalysis
Specific gravity
Protein level
To evaluate kidney function
Specific gravity: make sure tubules are concentrating
Total protein: to evaluate glomerular function
Clinical Signs of Renal Dz
- Nonspecific
- Dehydration
- inability to concentrate urine
- vomiting
- Halitosis, oral ulcerations, excessive salivation
- build up of nitrogenous wastes: comes from protein breakdown
- Build up of uremic toxins
- causes vomiting as well
- Palpable abnormalities
- Changes in water intake and / or urination
Acute renal failure
vs
Chronic renal failure
Acute renal failure
- anuric
Chronic renal failure:
- polyuric
- can’t concentrate
- dehydrated
- CBC
- mod anemia
- non regenerative
- normo chromic
- normo cytic
- No erythropoietin
Pyelonephritis: screamingly painful on palpation
Significant Clinical Findings
Distrubances in water intake and/or urine output
- early, most sig indicator of urinary tract dz
- PU/PD
- Anuria/oliguria: no output/reduced output
- Pollakiuria: inc frequency of urination
- Dysuria: difficulty urinating
- Incontinence
Polyuria/polydypsia
Production of urine and consumption of water in excess of normal
- Early indicator of renal dz
- Renal tubules have lost ability to concentrate urine
Extremely important clinical finding
- Primary renal dz
- Non renal disorders that affect abilitiy of kidney to concentrate urine
Diagnosis
- Consistently low urine S.G.
- Inc water intake (>100 ml/kg/day)
- Increased urine output (> 50 ml/kg/day)
Causes of PU/PD
1.
2.
3.
4.
5.
- Loss of medullary gradient or medullary washout
- Decreased ADH
- ADH resistance
- Iatrogenic
- Psycogenic
Loss of Medullary Gradient or medullary washout
Osmotic diuresis
Medullary Washout
Osmotic diuresis
- CRD
- Diabetes mellitus: Hyperglycemia, glucosuria
- Fanconi syndrome: Normoglycemia, glucosuria
- Tubules lose ability to resorb amino acids and glucose
- Post obstructive diuresis: unblocked obstructed cat
- Hyperkalemia will kill you
Medullary washout
- Any Chronic PU/PD
- Liver failure (decreased urea)
Decreased ADH Secretion
- Rare cause PU/PD
- Central DIabetes Insipidus
- Can be caused by damage to hypothalamus or pituitary gland
- Surgery
- Infection
- Inflammation
- Tumor
- Brain injury
Synthetic ADH
Vasopressin
ADH Resistance
Pyometra: endotoxin
Pyelonephritis: endotoxin
Cystitis: endotoxin
Hypercalcemia: interferes with ADH at distal tubules
Hypokalemia: decreased medullary gradient
Cushings
Addisons
Hyperthyroidism
Iatrogenic causes PU/PD
Diuretics
Corticosteroids
- Causes insulin resistance => higher glucose => osmotic
Anticonvulsants
Fluid therapy
- MAKE SURE URETHRA IS PATENT
Investigating PU/PD
History
Physical Exam
Diagnostic tests
- History
- Drugs
- Glucocorticoids
- Anticonvulsants
- Excessive thyroid
- Diuretics
- Estrus cycle
- Physical Exam
- Clinical signs of cushings:
- pyometra
- Diagnostic tests
* MDB: UA, CBC, Biochem profile
Anuria / Oliguria
Critical clinical findings
- Requires Agressive therapy
- Determine Potassium level ASAP
- Determine cause of anuria/oliguria
Oliguria/anuria
History and physical exam
- Exposure to nephrotoxins
* NSAIDs, Aminoglycosides, Ethylene Glycol - History of damage to Urinary tract
- Hydration status
* Interpret SG: dehydration is ‘pre-renal’ - Bradycardia or ECG changes
* Hyperkalemia - Abdominal palpation and imaging
* Calculi, masses, free fluid in abdomen, bladder integrity - Pass a catheter
* Establish / motinor urine
Laboratory Dxs of stone
1.
2.
3.
4.
5.
- Urinalysis: (SG, Casts, crystals)
- Bichem profile
- Potassium
- TCO2 (Bicarb)
- Uroabdomen: male foals with full bladders, Goats
- High BUN/Creatinine
- Low sodium
- High potassium
- Ethylene Glycol intoxication
- BUN/Creatinine
- low calcium (precipitates with the crystals)
- high anion gap
- seizures
- CBC findings
* non regenerative anemia = chronic renal failure (no EPO)
University of Minnesota for stone analysis
Dysuria
- (Painful, difficulty in urinating)
- Partial or complete urethral obstruction
* Identify quickly because uremia, hyperkalemia and death can occur w/in 48-72 of complete obstruction - Neuro
- UMN dz (inhibitory neurons): tight distended bladder, diff to express
- LMN dz: large flaccid bladder, easy to express
Biochemical Abnormalities
- Renal function tests
* BUN and Creatinine - Electrolytes
- Na and Cl (Resorbed)
- these both follow water
- K and Ph (excreted)
- Ca (hypercalcemia diff. to interpret)
- Albumin and lipids
* to evaluate glomerular function - Acid base and anion gap
Renal Function Tests
- BUN and Creatinine
- Markers for glomerular filtration rate (GFR)
- Dehydration will increase these (pre-renal azotemia)
- Used to monitor therapy and disease progression
Azotemia
vs
Uremia
Azotemia
- Increased BUN and/or Creatinine
- Due to a decrease GFR
- Consider muscle mass (If no muscle mass animal won’t have high creatinine)
Uremia
- azotemia plus clinical signs of disease
- Lethargy, depression, vomiting, weight loss, PU/PD, urine output disturbances, nose bleeds from uremic toxins coating platelets
BUN
(Blood Urea Nitrogen)
- Urea formed in liver from nitrogenous waste products like ammonia resulting from protein breakdown in gut
* Liver failure = low BUN - Passes through glomerular filter
- Inc levels in blood
- Dec flow rate in kidney = inc reabsorption
- Inc protein catabolism (Jens dogs tearing up rawhides to save furniture)
- Hemorrhage in GI tract
4. Reabsorbed by tubules at (25%-40%), inversely proportional to flow rate
- Unreliable indicator of renal dz in ruminants: cows excrete urea into alimentary tract
High BUN low Creatinine
top differential:
Upper GI bleed
Unless you’re Jen and feed rawhides all. the. time.
High Alk Phos
NORMAL IN
Growing animals (bone resporption and remodeling)
High alk phos with high bilirubin or other indicators of liver problems
- follow up on this
Ammonia (ammonium ion)
- Common byproduct of metabolism of nitrogenous compounds
- Smaller than urea and more mobile
- Urease bacteria make ammonium ion and inc pH of urine = struvite crystals
Increased BUN (Azotemia)
Pre-renal
renal
post renal
Pre-renal (doesn’t involve kidneys)
- Decreased filtration rate b/c of dehydration and dec blood flow to glomeruli
- High protein diet or GI hemorrhage (creatinine normal)
Renal (kidney disease)
- Dec filtration rate (kidneys not absorbing/secreting like they should)
Post Renal (UT dz past kidneys => bladder and urethra)
- Decreased filtration rate from obstruction
- Obstructed outflow/rupture in outflow tract
- most common in males (narrow urethra)
- Dx made by PE and Hx, more than lab eval
Pre-renal Azotemia
Results from dec blood flow to kidneys
- Dehydration
- Shock: cardiovascular, hypovolemic, endotoxic
Kidneys attempt to conserve water to inc GFR
Urine SG elevated
- Cats > 1.035
- Dogs > 1.030
- Horses and cows > 1.025
Elevations in PCV, RBC, Cl, Plasma protein/albumin
Analyze Urinalysis PRIOR to fluid therapy
Crystals common in horse urine
Calcium carbonate
- Brown radiating spheres
- dumbells
- alkaline urine
Calcium oxalate
- Dihydrate
- squares with two lines
- Seen wtih cushings
- Ingestion oxalate containing plants
- Monohydrate
- Picket fence (ethylene glylcol poisoning dogs)
- NOT 3D
Pre-Renal Azotemia NOTE
High Urine SG doesn’t rule out renal disease
Possibility of glomerular dz w/o tubular disease
=> Results in significant proteinuria with a benign sediment still maintaining ability to concentrate urine
Tx for endotoxic shock
Want to increase blood pressure and blood flow
- Epinephrin
- Dopamine
- Fluids
- Waxy casts and isothenuria
- Granular Casts
- Hyaline casts
1. Waxy casts were once cellular casts => NOT NORMAL
- Granular casts: normal cellular turn over NBD
- Hyaline casts: maybe ate a lot of protein: NBD
Granular casts
vs
Cellular casts
Granular casts => can be normal cellular turnover
Cellular casts => Shedding whole renal tubule, never normal
- can be aminoglycoside intoxication
Pre-renal azotemia
PCV
NA, Cl
Total protein
Pre-renal azotemia indicates dehydration
Should have a higher PCV (relative erythrocytosis)
Na and Cl tend to be increased
Higher total protein
Hypoalbuminemia Tx
- Hetestarch
- Plasma
- Synthetic proteins
- Epinephrine (vasoconstriction)
Renal Azotemia IMP NUMBERS
- Concentrating ability lost when 2/3 nephrons lost
* Spec Grav goes first - When 75 % nephrons non-function
* Increase BUN and Creatinine => Azotemia happens second
High BUN and Low Creatinine
a.
b.
-look for:
a. Cat with chronic renal failure and no muscle mass to break down
b. young healthy-ish dog with an upper GI bleed
- Blood is a great protein
- Look for hypochromic, microcytic, non-regenerative anemia (1+ polychromasia is not regenerative 80K vs 300K retics)
Things that keep renal tubules from reacting to ADH
1. Booze
2. Steroids
- Prednisone
- Cortisol (cushings)
3. Endotoxins
4. Calcium
Urine will not be adequately concentrated if azotemia is due to:
Renal dz
Hyposthenuria (<1.008) is NOT a sign of
Usually indicates
Renal failure
Abnormally dilute urine from
- Central diabetes insipidus
- blockage of ADH
Post-renal Azotemia general features facts
Blocked cats
Azotemia with hyperkalemia and hyponatremia
Urine spec grav not helpful
Eval of abdominal fluid
- low protein
- BUN vs Creatinine
Renal dz w/o Azotemia
Greater than 25% functional nephrons
Requires urinalysis to detect renal dz
- Proteinuria
- Glucosuria w/o hyperglycemia (Fanconi)
- Casts
- Reduced ability to concentrate in dehydrated animal
Monitoring of animals receiving aminoglycosides
- monitor UA and serum BUN and creatinine
Evaluatin of animals with Dec BUN
NBD large animals: they look for hypercalcemia
Could be NBD in small animal
- Can happen in vegetarians, or inc GFR, or overhydration
Hepatic failure:
- BUN made in liver from ammonium ions
- Check other liver products to see if they are low
- Glucose
- Albumin
- PT/PTT
Evaluation of Creatinine
Product of muscle metabolism
Greyhounds tend to have higher Creatinine
Not a product of diet or GI hemorrhage
Inc in severe muscle damage
Electrolytes in Urinary Tract Disease
Potassium
- excreted in kidneys
Sodium
Chloride and Bicarb
Phophorus
- excreted by kidneys so inc with renals dz
Calcium
- Renal failure in horse: hypocalcemia…?
Potassium
Can inc
- Postrenal azotemia
- Renal azotemia
Hyperkalemia often assoc w/
- anuric renal failure
- oliguric renal failure
Hypokalemia develops in
- polyuric renal failure
- mostly cats, cows, 25% dogs
- NOT HORSES
Hypophosphatemia will cause
Intravascular hemolysis
no phospohorus => no atp => no cell membrane
High potassium=
Low potassium=
cardiac arrest
respiratory arrest
Decreased Potassium/hypokalemia in large animals
Anorexia
PCV in the toilet is what kind of renal failure?
Chronic renal failure
PCO2
vs
TCO2
PCO2: how well your lungs are breathing off acid
- Blood gas
TCO2: bicarb
- Serum biochemistry
Bicarb
Gets titrated out of body with acid
Anion gap stuff
Chloride and Bicarb slide
- Cl- dec in horses and cattle with renal dz
- Cl- can be elevated in prerenal azotemia
- Cl- and bicarb regulated by the kidney
* levels may vary inversely in acidosis - Biochemical profile TCO2 = Bicarbonate (HCO3-)
- often reduced in cats and dogs b/c of lack of excretion or organic acid waste
- gets titrated out by lactic acid and uremic acid
Two types of metabolic acidosis
Loss of bicarb, kidneys conserve Cl-
- normal anion gap
Build up of acids (Lactic acid, uremic acids, ethylene glycol, DKA)
- Bicarbonate not lost, kidneys do not conserve Cl-
- Increased anion gap
Inc lactic acid associated with
Hypovolemia
Chloride
Chloride and Sodium usually in 1:1 ratio
Selective loss/gain of Chloride compared to sodium indicates acid-base prob
Pseudo addisons
vs
addisons
Pseudo addisons (whipworm dz)
- Causes extreme secretory diarrhea
- lose electrolytes
- looks like adrenal glands aren’t working
- Na/K ratio effed
- Na and Cl extremely low
- makes it look like your body can’t absorb anything
Addisons
- when adrenal glands don’t work and make cortisol
- ACH stim if no cortisol put on Pred
- must give these animal Na and Cl or they’ll DIE
- undiagnosed addisons in sx = patient will DIE
Loss of Chloride in Excess of Sodium
Not on test
Horses:
- sweating
- diarrhea
Cattle: can lose in saliva
Gastric reflux
Phosphorus
Hyperphosphatemia
Hyperphosphatemia common in renal dz
- due to dec exretion of P
- exception is cattle and horses
- Occurs rapidly in ARF, b/c dec GFR
- Steadily progressive in CRF
Controlling hyperphosphatemia imp
- Secondary hyperparathyroidism w/ bone resporption and renal mineralization
- Renal damage due to elevated P
Uremic Frosting
When Ca X P > 70
Crystalizes things throughout body incl. kidneys
Calcium
Hypercalcemia
Hypocalcemia
Hypercalcemia
- common in horses with seere renal dz
- rare in other species
- can cause renal dz in dogs and cats b/c it makes distal tubules refractory to ADH
Hypocalcemia
- May be seen in cats and cattle with CRF due to polyuria
Acid Base abnormalities with Renal DZ
Metabolic acidosis
- common in cats and dogs
- decreased excretion of H+ and organic acid products
- loss of ability to conserve / make bicarb
Ruminants
- metabolic alkalosis
- Rumen stasis and sequestration of HCl
Albumin and Lipids in renal dz
Pre-renal azotemia: albumin inc
Renal dz: Normal or dec albumin
Protein losing nephropathy
- Glomerular dz
- Protein : Creatinine ratio
- Results in hypercholesterolemia
-
Nephrotic syndrome
- Proteinuria
- hypoalbuminemia
- hypercholesterolemia
- peripheral pitting edema
ARF
vs
CRF
Why care?
ARF
- Toxic or ischemic damage to kidney
- Guarded short-term prognosis
- Good long-term prognosis if renal function restored
CRF
- Cause not usually identified
- Good short term prognosis
- Progressive dz => bad long-term prognosis
Distinguishing ARF & CRF
ARF
- Initially anuric or oliguric
- Later polyuric
- Typically good BCS
CRF
- Usually present PU/PD
- Will become oliguric or anuric in end stage
- Usually anemic: NO EPO
Lab finding
ARF: Anuric / Oliguric
Hyperkalemia
Metabolic acidosis with high anion gap
Na & Cl normal or high due to dehydration
NOT ANEMIC
Possibly inc phosphorus
Lab findings
CRF: Polyuric
Na and K likely to be low b/c of renal loss
Cl may be elevated due to loss of bicarb
Metabolic acidosis with normal anion gap
Non-regenerative anemia of CRF
Possibly elevated phosphorus
- Trace of +1 protein dipstick and high SSA test, be concerned for….
- High Protein on dipstick and SSA…..
- Multiple myeloma
- Not multiple myeloma
Bilirubin crystals in cats is bad, can indicate
extravascular hemolysis
liver disease
Cats with renal failure will have high
Phosphorus and calcium
Ammonium biurate crystals:
- In Dalmations or bulldogs:
- In other dogs:
- NBD
- hepatic disease
Rough catheterization can cause
Proteinuria and heme
