Measuring Renal Function

Question 1

What do we use Urinalysis for

Answer 1

Quality control
Constituents
Volume
Concentration

Question 2

What do abnormal constituents include

Answer 2

Glucose
Blood
Protein
Ketones
Cells

Question 3

What are the different urine volumes for normal, polyuria, oliguria, anuria

Answer 3

Normal = 1-2mls/kg/hr
Polyuria over 2mls/kg/hr
Oliguria = less than 1ml/kg/hr
Anuria = no urine flow

Question 4

What is the normal specific gravity and initial filtrate for a dog

Answer 4

Specific gravity = 1.001-1.075
Initial filtrate = 1.008-1.012 (protein free plasma)
If urine specific gravity as low as this = isoathenuria. Suggest kidney pathology that is disrupting its ability to concentrate

Question 5

What specific gravity is evidence that animals can concentrate there urine

Answer 5

Cat = over 1.035
Dog = over 1.030

Question 6

Under normal circumstances what is the net excretion and reabsorption of

Answer 6

Net excretion = phosphate, potassium, protons
Reabsorption = bicarbonate, glucose

Question 7

In kidney disease what are the common changes in blood

Answer 7

Hyperkalaemia (can also get excess loss and hypokalaemia in chronic disease)
Hyperphosphataemia
Metabolic acidosis

Question 8

What is Azotaemia

Answer 8

If urea and creatine increased above normal al values. It is a marker of decreased GFR

Question 9

What is post renal Azotaemia

Answer 9

If renal function is normal but urine outflow is blocked. Life threatening changes in fluid and electrolyte balance.
Diagnosis straight forward

Question 10

What is pre renal Azotaemia

Answer 10

Reduced GFR due to reduced blood pressure
Dehydration
Cardiovascular disease

Question 11

What do we see with pre renal Azotaemia

Answer 11

Large systemic reduction in blood pressure = reduced GFR
No pathology in the kidney itself it occurs upstream of the kidney. GFR is reduced animal is able to concentrate its urine.

Question 12

What is renal Azotaemia

Answer 12

Due to renal disease
Pathology is directly affecting renal function.
GFR reduced
Animal is not producing much urine or is not able to concentrate

Question 13

How do we diagnose Azotaemia

Answer 13

Dehydrated hypovolaemic animal will have decreased GFR and Azotaemia but if kidney is functioning normally. ADH will be released and urine will be concentrated

Question 14

What are the biochemistry signs of reduced kidney function

Answer 14

Increased nitrogenous waste products
Increased concentration of inorganic phosphate
Increased blood concentration of potassium (although anorexic animal can be hypokalaemic)
Decrease in concentration of bicarbonate

Question 15

What are the signs of urine of reduced kidney function

Answer 15

Lack of concentrating ability
Abnormal volume either way

Question 16

What are the effects of acute kidney injury

Answer 16

Rapid life threatening impairment in kidney function
GFR reduced and loss in ability to concentrate urine
Urine output can be zero, reduced or increased

Question 17

What are the effects of chronic kidney disease

Answer 17

More long term progressive loss of kidney function
GFR is reduced and loss in ability to concentrate urine
Urine output increased