Azotaemia and urinalysis

Question 1

What does myoglobin in urine indicate?

Answer 1

muscle damage

Question 2

What substances can be found in the urine the indicate disease?

Answer 2

Crystals (urolithiasis)
Myoglobin
Bilirubin
RBCs
Haemoglobin
WBCs

Question 3

Describe the use of the gross appearance of urine in urinalysis

Answer 3

Colour:
- should be pale yellow, yellow or amber
- abnormal colour can be caused by diet, meds, environment or illness
Turbidity:
- should be clear
- cloudiness caused by suspended material e.g., bacteria
Smell:
- should be relatively odourless
- strong ammonia smell suggests infection

Question 5

How is pH used in urinalysis?

Answer 5

Normal = 6-7.5
Increased pH (alkalotic) may results from UTI
Diets high in animal protein or milk => lower pH

Question 6

How is urine glucose used in urinalysis

Answer 6

Glucose not normally present in detectable quantities on dipstick
Glucosuria occurs due to high blood glucose levels e.g., diabetes mellitus
If blood glucose is normal with glucosuria = renal tubular dysfunction

Question 7

Describe urine ketones in urinalysis

Answer 7

Normally undetectable levels
Ketonuria indicates shift from carb metabolism to fat metabolism due to ketosis and starvation

Question 8

How is occult blood used in urinalysis

Answer 8

Detects haem-containing substances e.g., haemoglobin
Red cells in sediment indicates haematuria is causing occult blood

Question 9

Describe bilirubin in urinalysis

Answer 9

Should not be present (except small amount in healthy dogs)
Renal threshold for bilirubin is low in most animals

Question 10

Describe microscopic examination of urine sediment in urinalysis

Answer 10

Cells:
- RBCs should not be present in high levels
- WBCs at high levels suggests infection (pyuria)
Casts
Crystals

Question 11

What are urine casts?

Answer 11

Cylindrical moulds formed in the lumen of renal tubules
Made up of mucoprotein secreted by renal tubule cells
Caused by concentrated urine, decreased urine flow, acidic urine

Question 12

What is azotaemia?

Answer 12

An increase in urea nitrogen and/or creatinine in the blood due to decreased renal excretion

Question 13

Why is azotaemia a useful marker in clinical practice?

Answer 13

Indicates there is a problem with the kidneys filtering nitrogenous waste or products of muscle metabolism
Can also be due to decreased delivery of nitrogenous waste due to decreased blood flow or renal disease itself

Question 14

What are the types of azotaemia?

Answer 14

Pre-renal azotaemia = azotaemia occurs because of systemic factors that result in inadequate renal perfusion
Renal azotaemia = due to reduced function of the kidneys
Post-renal azotaemia = caused by a problem after the kidneys (ureters, bladder or urethra)

Question 15

Describe the blood biochemistry, urinalysis and clinical signs of pre-renal azotaemia

Answer 15

Concentrated urine - high USG as kidneys working to reduce fluid loss
Azotaemia
Clinical signs of hypovolaemia and dehydration

Question 16

What are the possible causes of pre-renal azotaemia?

Answer 16

Hypovolaemia e.g., blood loss, shock
Dehydration
Low CO
Poor perfusion
Hypotension

Question 17

what are the possible causes of post-renal azotaemia

Answer 17

Obstruction (urolithiasis)
Rupture (uroabdomen)