examination of kidney function

Question 1

diagnosis of kidney function based on anamnesis data

Answer 1

• change in body weight
  
  • oedema or ascites, body weight will increase
  • chronic kidney disease, animals generally loose weight
• body condition changes
  
  • chronic kidney failure = poor body condition
• general status, behaviour
  
  • severe kidney disease = depression
• fur quality, skin turgor
  
  • unkept fur because of poor nutritional status and behavioural changes
  • decreased skin turgor due to dehydration (usually chronic kidney failure)
• shape of body
  
  • swelling of limbs and ventral parts of the abdomen and throacic cavities
  • oedema formation under the skin
• water intake
  
  • chronic kidney failure = increased intake
  • acute kidney failure = decreased intake
• urine output
  
  • often not used
  • chronic kidney failure = polyuria
  • acute kidney failure = oligouria

Question 2

list the tests used to assess glomerular function

Answer 2

1. blood urea concentration
2. blood creatinin concentration
3. clearance (GFR)
4. UPC - urinary protein creatinin
5. (IP)
6. (SDMA)

Question 3

tests to determine tubular function

Answer 3

1. urine specific gravity
2. urine sedimentation
3. fractional electrolyte clearance
4. enzymuria
5. water deprivation test

Question 4

methods for determing blood urea

Answer 4

• urea colour test
  
  • NH₃ in water forms NH₄
  • forms green colour in alkaline PH with Na - hypochloride and salycilic acid
• Enzymatic urea test

Question 5

Pre renal causes of increase in blood urea

Answer 5

• increased nitrogen intake
• In Ru: poor energy status of the rumen
• increased intestinal protein catabolism (increased NH₃ production by bacteria)
• intestinal or gastric bleeding
• haemolysis
• decreased blood perfusion of the kidneys
  
  • shock
  • hypotension
  • dehydration
  • cardiac failure
  • Addisons
  • thromboembolism
  • strangulation of the renal artery

Question 6

renal factors of blood urea increase

Answer 6

• kidney function
  
  • kidney tumour
  • CKD (chronic kidney disease)
  • AKI
  • hypoplasia - 1 sided
  • Polycystic disease
  • Amyloidosis
  • glomerular and tubular nephritis

Question 7

Post renal factors increasing blood urea concentration

Answer 7

• inhibition of urine flow
  
  • occlusion of pelvic urethra/ureter
• rupture of the urinary bladder/ ureter/ urethra, kidneys
  
  • uroperitoneum
    
    • urine in abdominal cavity
    • quickly absorbed by peritoneal blood vessels
    • very bad
    • emergency surgery is required

Question 8

causes of decreased blood urea concentration

Answer 8

• impaired liver function - decreased urea synthesis
• haemodilution
• decreased protein intake (starvation)

Question 9

methods of creatinin determination

Answer 9

1. Jaffe method - creatinine forms yelow orange complex with picric acid at alkaline PH
2. Enzymatic method - challenging to do

Jaffe method is prefered

Question 10

causes of blood creatinin to increase

Answer 10

• meat content of diet
  
  • mostly high protein diet has a long term indirect effect on blood creatinin concentration through increasing the bodies mass
• state of muscles
  
  • muscle necrosis
    
    • inflammation
    • injury

Question 11

causes for blood creatinin to decrease

Answer 11

• cachexia (muscle wasting due to chronic disease
  
  • liver failure
  • PSS
• Polyuria
• polydypsia
• anabolic steroids

Question 12

what does an unusally high creatinin level indicate

Answer 12

GFR decrease

Question 13

what happens when the GFR decreases by 1/4

Answer 13

creatinin concentration increases by 100-150%

Question 14

how to calculate creatinin clearance

Answer 14

C = U x V / P

C = clearance

U = creatine conc. in urine

V = urine output per minute

P = creatinin conc. in plasma

Question 15

why is SDMA often used for diagnostics of glomerular function

Answer 15

it is more reliable

not based on muscle mass