Clinical pathology: clinical chemistry-(i)Evaluation of renal function

Question 1

Are ketones usually present in the urine of dogs and cats?

Answer 1

No, not normally present

Question 2

What can lead to ketone production?

Answer 2

Inadequate consumption of carbohydrate or impaired utilisation of carbohydrates

Question 3

Give 5 causes of ketonuria.

Answer 3

(i)diabetic keto-acidosis
(ii)starvation or prolonged fasting
-glycogen storage disease
-low carbohydrate-high fat diet
-persistent hypoglycaemia(decreased insulin induces ketone formation)
Check flashcard folder numbers 1 and 2 for further information

Question 4

Bilirubin: if present in the urine, in which form is it usually found?

Answer 4

-Conjugated form

Question 5

• In which type of urine is it normal to have a small amount of bilirubin?
• Is this a common finding in cats?

Answer 5

• Concentrated urine of normal male dogs

- This is not normally found in cat urine.

Question 6

How is bilirubin made in the body?

Answer 6

-Bilirubin is derived from the breakdown of heme by the reticuloendothelial system.

Question 7

Give 5 causes of bilirubinuria.

Answer 7

• Haemolysis
• Liver disease
• Extrahepatic biliary obstruction
• Fever
• Starvation

Question 8

What is the term used to describe an increase in the level of bilirubin in the blood.

Answer 8

Hyperbilirubinaemia

Question 9

What is the disadvantage of using dipstick when testing for the presence of blood in urine?

Answer 9

Dipstick tests do not differentiate from intact RBCs or haemoglobin.

Question 10

Give 8 different causes of haemoglobinuria from haemolysis.

Answer 10

-Transfusion reaction
-Immune mediated haemolytic anaemia
-Disseminated intravascular coagulation(DIC)
-Splenic torsion
-Severe hypophosphatemia
-Heat stroke
Zinc toxicity
-Phosphofructokinase or pyruvate kinase deficiency

Question 11

Describe how to prepare a urinary sediment.

Answer 11

1/Sediment preparation

a. Perform on fresh urine samples.
b. Centrifuge 5 to 10 ml of urine at 1000 to 1500 rpm for 5 minutes. stain with Sedi-Stain.
c. Number of casts is recorded per low-power field, and cells are recorded per high-power field.

Question 12

What is the term used to describe excessive number of RBCs in urine?

Answer 12

Haematuria

Question 13

Give 12 different causes of haematuria.

Answer 13

-trauma
-urolithiasis
-neoplasia
-UTIs idiopathic feline lower urinary tract disease
chemically induced cystities
-systemic diseases associated with haemorrhage
-renal infarct
-nephritis
-nephrosis
-parasites
-nephrosis
-genital tract contamination

Question 14

What is the term used to describe excessive WBC’s in urine sediment? What does this indicate?

Answer 14

Pyuria

It indicates inflammation somewhere in the urinary tract or contamination from the genital tract.

Question 15

What would cause clumped WBC’s?

Answer 15

Clumped WBC’s are usuallly due to infectious organisms.

Question 16

What are the 3 different types of epithelial cells that can be found in the urine?

Answer 16

(i) Squamous epithelial cells
(ii) Transitional epithelial cells
(iii) Renal epithelial cells

Question 17

Is the presence of each of the different types of epithelial cells in urine normal?
For transitional epithelial cells and renal epithelial cells, when can their values be increased?

Answer 17

-Squamous epithelial cells(large, polygonal cells with small, round nuclei)
This is a common finding in voided or catheterised samples.
-Transitional epithelial cells
A small number is normal. Usually increased in infection, irritation or neoplasia
-Clumps or “rafts” are most common in neoplasia
-Renal epithelial cells
(i)Small epithelial cells from the renal tubules or pelvis
(ii)Appearance in urine is never normal and is observed in patients with ischaemic, nephrotoxic or degenerative renal disease.

Question 18

What are casts?

Answer 18

Casts are cylindrical molds formed in the renal tubules composed of aggregated protein or cells.

Question 19

Give 5 examples of casts in urine.

Answer 19

• Hyaline
• Cellular casts
• Granular casts
• Waxy casts
• Broad casts

Question 20

How is hyaline formed as a cast and what may trigger its formation?

Answer 20

It is a pure protein precipitates of Tamm-Horsfall mucoprotein.
It dissolves rapidly in dilute or alkaline urine.
It has the least pathologic significance and may form transiently with fever, exercise or passive congestion to the kidney.

Question 21

What are the 6 different types of cellular casts and describe how they are formed?

Answer 21

(i) White cell casts-suggest pyelonephritis nbut may also be caused by interstitial neohritism nephrosis or glomerulonephritis.
(ii) Red cell casts are fragile and rarely found. They may be noted in acute glomerulonephritis.

(iii) Hameoglobin casts are casts where the haemoglobin colour is retained in the cast.
(iv) Renal epithelial casts -severe tubular injury and suggest acute tubular necrosis or pyelonephritis.
(v) Renal fragments are a variant of epithelial casts where portions of the renal tubules slough into urine, their appearance suggests severe renal injury.
(vi) Mixed casts contain multiple cell types.

NOTE: Pyelonephritis is inflammation of the kidneys.

Question 22

What do granular casts represent? How can fatty casts be formed?

Answer 22

granular casts represent the degeneration of cells or precipitation of filtered plasma proteins.
fatty casts are a type of granular cast that may be seen in nephrotic syndrome or diabetes mellitus.

Question 23

What do waxy casts represent?

Answer 23

Waxy casts represent the final stage of degeneration of granular casts. they suggest chronic intrarenal stasis and are found in advanced chronic renal disease.

Question 24

What are broad casts and how are they formed?

Answer 24

Broad casts are wide casts that form in collecting ducts or dilated distal nephron. they suggest severe intrarenal stasis and tubular obstruction.

Question 25

Give 4 examples where there can be bacteriuria without pyuria.

Answer 25

(i) hyperadrenocorticism
(ii) diabetes mellitus
(iii) immunosuppression
(iv) cats with chronic renal disease

NOTE: The absence of bacteria does not rule out UTI.
Yeasts and fungal hyphae in sediment are usually contaminant.

Question 26

How are crystals formed in urine?

Answer 26

They are usually an artifact of storage urine and refrigeration.

Question 27

Where are struvite crystals usually found?

Answer 27

Struvite crystals are found in alkaline urine and may be found in normal animals or in those with struvite urinary stones.

Question 28

In what type of urine is each of the following crystals found and where relevant, state the condition to which they are usually associated.

(i) calcium phsophate crystals
(ii) calcium carbonate crystals
(iii) amorphous phosphate crystals
(iv) ammonium biurate crystals
(v) uric acid crystals
(vii) urate crystals
(viii) calcium oxalate crystals
(ix) Cystine crystals
(x) billirubin crystals
(xi) oxalate monohydrate

Answer 28

(i) i)calcium phsophate crystals-alkaline urine
(ii) calcium carbonate crystals-alkaline urine
(iii) calcium carbonate crystals-alklaine urine
(iii) amorphous phosphate crystals-alkaline urine
(iv) ammonium biurate crystals-alkaline urine
(v) uric acid crystals-acidic urine and they are associated with the Dalmatian breed
(vii) urate crystals assoaciated with liver disease and portosystemic shunt
(viii) calcium oxalate crystals-acidic urine
(ix) Cystine crystals-acidic urine and associated with cystinuria
(x) billirubin crystals found normally in concentrated dog urine
(xi) oxalate monohydrate crystals are found in acute renal failure owing to ethylene glycol ingestion.

Question 29

Is it normal to find sperm in the urine of intact males?

Answer 29

Yes

Question 30

In what condition could there be the presence of amorphous debris in the urine?

Answer 30

Amorphous debris associated with acute intrinsic renal failure

Question 31

When can mucous threads or fibrin strands be seen?

Answer 31

Mucous threads or fibrin strands seen in lower urinary tract or genital inflammation

Question 32

Are parasite ova from Doctophyma renale or Capillaria plica in the urine a common finding?

Answer 32

No, parasite ova from Doctophyma renale or Capillaria plica are rarely seen in the urine.

Question 33

What are lipid droplets associated with?

Answer 33

Lipid droplets are associated with cellular degeneration.
NOTE: Foreign material may be present, especially in voided samples.
Precipitates of urine stain may look like urinary crystals.