URINALYSIS

2

OVERVIEW

1. Urinalysis

2. Serum/plasma urea & creatinine concentrations

3. Urine protein to creatinine ratio (UPC ratio)

3

1.URINALYSIS

MAIN INDICATIONS ARE: • Evaluation of renal & lower urinary tract abnormalities

• Assessment of some metabolic/endocrine disorders• Assessment of state of hydration

4

Urinalysis

Gross evaluation

Specific gravity (SG)

Biochemical analysis

Sediment examination (microscopy)

Culture

5

GROSS EVALUATION: COLOUR

Red discolourationUrine from healthy animals can vary in colour but is usually light, mild or dark yellow

Red discolouration may indicate haemoglobinuria, myoglobinuria or haematuria.

6

GROSS EVALUATION: TURBIDITY

Turbid urine (healthy horse)

Upper sample :Clear urineLower sample:Turbid

turbidity in urine from a cow with

pyelonephritis

7

TURBIDITY

Healthy horses and rabbits may have turbid urine due to high concentration of mucin and crystals. In other species turbidity can indicate the presence of sediment.

On refrigeration, urine samples may become turbid from crystallisation of minerals which were in solution, and they may clear when returned to room temperature

8

Urinalysis

Gross evaluation

Specific gravity (SG)

Biochemical analysis

Sediment examination (microscopy)

Culture

9

SPECIFIC GRAVITY (SG)

Ratio of weight (density) of urine to that of an equal volume of water

at the same temperature. No units.

Values depend on:

- hydration status and water intake

- the kidney’s concentrating ability

It is a test of renal tubular function

Hydration status can be determined by assessing skin turgor or by measurement of serum albumin, or PCV and total proteins.

10

– Reagent test strips are unreliable for animals/Always use the refractometer

– If the urine is turbid, centrifuge it before measuring SG of the supernatant

1.0001.0101.0201.0301.0401.050

SPECIFIC GRAVITY (SG): MEASUREMENT

11

SG: INTERPRETATION

HYPERSTHENURIA: concentrated urine- >1.012-urine of healthy, normally hydrated animals

ISOSTHENURIA: urine neither concentrated nor diluted-1.007-1.012 (urine SG = plasma filtrate SG)-persistent isosthenuria warrants further investigation

HYPOSTHENURIA: urine is more diluted than plasma - <1.007- persistent hyposthenuria warrants further investigation

12

SG: INTERPRETATION

* The range of values for SG can vary according to water intake and hydration status. Usually SG in normal concentrated urine is >1.030

* WATER DEPRIVATION TEST* Contra-indication: It should never be carried out in depressed,

dehydrated or azotemic animals, or if renal failure is suspected.* Indication: Confirmation of the animals ability to concentrate its urine

when water is withheld.* Protocol: The urine SG is monitored every 2 hours until 5% of body

weight is lost, or the urine SG is >1.020. * Interpretation:

* If the urine SG increases to 1.020, tubular function and ADH availability are confirmed.

* If the urine SG remains <1.020, diabetes insipidus is suspected.

13

Urinalysis

Gross evaluation

Specific gravity (SG)

Biochemical analysis

Sediment examination (microscopy)

Culture

14

BIOCHEMICAL ANALYSIS URINE STRIPS

Always follow manufacturer instructions

15

EXAMPLE OF A URINE STRIP CHART

16

GLUCOSE

- Glucose is not normally found in urine of healthy animals

- Causes of glycosuria • Persistent hyperglycaemia

- Diabetes mellitus

• Transient hyperglycaemia- Stress in cats

- Drugs (xylazine, ketamine)

- IV fluids containing glucose

- Convulsions

• Renal tubular disorders- Fanconi syndrome

- Primary glucosuria

17

BILIRUBIN

– Not accurate for dogs/cats• Tests utilising a tablet (ictotest) can be more accurate than strip-

tests

• Light can break down bilirubin

– Trace to + normal in healthy dogs.No bilirubin present in the urine of other healthy animals

– The bilirubin in the urine is water-soluble conjugated bilirubin

– Causes of bilirubinuria

• Same as causes of bilirubinaemia

18

KETONES

– Accurate test for animals

• Does not detect -hydroxybutyric acid

– Ketones are not present in the urine of clinically healthy

animals

• Trace can be normal in rabbits

– Causes of ketonuria

• Diabetes mellitus, pregnancy, starvation, ketosis, immediately after

calving in high–producing dairy cows

N.B. Many disorders causing anorexia in cattle (e.g. mastitis, metritis, pneumonia) will cause ketonaemia and ketonuria, but levels of ketones are generally not as high as in primary ketosis.

19

BLOOD / HAEMOGLOBIN

- Accurate test for animals

- Detects intact RBCs, haemoglobin or myoglobin

- Follow-up positive result with sediment examination

- Interpret positive result in conjunction with the method

of urine collection (cystocentesis can be a cause of presence of

blood in urine)

20

pH– Acceptable test for animals- Carnivores:

• acidic urine is normal if fed a meat diet

• alkaline urine usually reflects urinary tract infection

- Herbivores:

• alkaline urine is normal

• acidic urine may reflect increased protein catabolisme.g. high protein diet, starvation, fever, nursing animals

– Some drugs can influence pH– Not an accurate indicator of systemic acid/base balance

21

PROTEIN

– Acceptable test for animals but can give false positive reaction in alkaline samples.

– Test detects mainly albumin. Does not detect globulins

– Always interpret in conjunction with SG and sediment examination (it is not abnormal to have trace protein in concentrated urine but always abnormal finding in diluted urine).

– Common causes of proteinuria:

• urogenital haemorrhage

• urogenital inflammation

• renal protein loss

22

NITRITE, UROBILINOGEN, LEUKOCYTES

- Nitrite• Positive results may indicate bacterial infection

• false negative results occur commonly

- Urobilinogen• Questionable clinical usefulness

- Leukocytes• False negative results common in dogs

• False positive results common in cats

NONE ARE RELIABLE IN EXAMINING ANIMAL URINE

23

2. Serum urea & creatinine concentrations

24

UREA

TISSUES

proteins NH4+

LIVER

UreaDietary Proteins bacteria NH4

+

Urea cycle

Urea

GASTROINTESTINAL TRACT

NH4+

Urea

Urea

Urea in urine

KIDNEYS

BLOOD

75%

25%

25

UREA and creatinine

– Glomeruli: 75% of urea is excreted (excretion or when glomerular filtration rate or )

– Tubules: Urea is reabsorbed (reabsorption or when glomerular filtration rate or )

– Creatinine is derived from creatine-phosphate, creatinine is excreted via the glomeruli. It is not reabsorbed in the tubules so excretion of creatinine is a measure of glomerular filtration rate.

26

BUN vs. UREA

– BUN = blood urea nitrogen= concentration of the nitrogen

component of urea in blood

– BUN value is Lower than urea value. BUN:Urea ratio is

approximately 1:2

– But the term BUN is used interchangeably with urea

27

CREATININE

MUSCLE

creatine creatinine

BLOOD creatinine

KIDNEYS

creatinine

Creatinine inurine

INTESTINES creatinine NH4+

28

AZOTAEMIA

- Increased serum/plasma urea & creatinine concentrations

URAEMIA

– Marked azotaemia and clinical signs (vomiting,

anorexia, gastrointestinal ulceration)

29

AZOTAEMIA

CAUSES

PRE-RENAL

RENAL

POST-RENAL

30

PRE-RENAL AZOTAEMIA

- DECREASED RENAL PERFUSION - Hypovolaemia, dehydration, cardiovascular disease

Urea is and creatinine Normal / Urine specific gravity is

- INCREASED UREA PRODUCTION

- G.I. TRACT HAEMORRHAGE

Urea is and creatinine is Normal

- HIGH PROTEIN DIET

Urea is and creatinine is Normal

31

RENAL AZOTAEMIA

- RENAL DISEASE

- ONLY evident when more than 60-75% of nephrons

are compromised

• Urea and creatinine are

• Urine is inadequately concentrated

32

POST-RENAL AZOTAEMIA

- URINARY TRACT OBSTRUCTION

• ureter, urethra

- URINARY TRACT RUPTURE

• ureter, bladder, urethra

- Urea and creatinine are

33

LOW SERUM/PLASMA UREA: CAUSES

– Decreased Liver Function– Portosystemic shunt– Increased Excretion

• Extreme PU/PD

• Overhydration– Low protein intake

Young Animals have a lower reference range

34

RUMINANTS / HORSES

- Excrete most of urea via the gut (very little via kidneys). So

blood urea can be normal despite severe renal disease.

- Therefore blood creatinine is a more sensitive indicator of

renal disease

35

3.Urine protein to urine creatinine ratio (UPC ratio)

36

UPC RATIO– Used to assess the clinical significance of proteinuria– Total protein & creatinine concentrations are measured in a single

urine sample and expressed in the same units

UPC RATIO INTERPRETATION

< 1.0 Proteinuria if present is not significant

MILD/MODERATE INCREASES (1-2)

Significant proteinuria from:

urogenital haemorrhage

urogenital inflammation

glomerular protein loss

MODERATE/SEVERE INCREASES (>2)

Usually glomerular protein loss

Urine Sediment Examination

Produced by centrifugation of urine onto a slide Looking for:

Abnormal crystalsCells Infectious agentsCastsContaminants

37

38

Ammonium biurate: suggestive of liver dysfunction and/or portosystemic shunting

39

Conjugated bilirubin: normal in dogs, but abnormal in other species. Suggests conjugated bilirubinemia

40

Calcium oxalate: suggestive of hypercalciuria, hyperoxaluria (dietary, ethylene glycol) or calcium oxalate uroliths

Can occur normally if urine has been stored

41

Magnesium ammonium phosphate (struvite) – present in normal animals but excessive amounts can be an indicator of struvite uroliths or mixed uroliths

Common in bacterial-induced alkalinuria

42

Calcium oxalate monohydrate – suggestive of hypercalciuria or EG toxicity

43

Cysteine – indicative of disruption of cysteine metabolism/catabolism (drug induced or inborn error in metabolism

44

Drug-associated - sulfonamides

45

Tyrosine – associated with severe liver disease

46

Tyrosine – associated with severe liver disease

47

RBCs – up to 5 RBC per high power field is normal. Increased RBCs in urine generally indicates hemorrhage into the bladder or urethra (artifact with catheter collection in some cases)

48

WBCs – up to 5 WBC per high power field is normal, higher levels suggest infection somewhere within the urinary tract

49

Transitional epithelial cells from renal pelvis, ureters, urinary bladder or urethra

Morphology used for detection of neoplastic change (cytology)

50

Squamous epithelial cells – indicator of contamination from skin, prepuce etc

51

Neoplastic cells – commonly transitional cell carcinomas

52

Bacteria – bacili on the right, cocci on the left. Presence is always abnormal – either infection or contamination (storage, collection)

53

Fungi – presence is always abnormal – Candidiasis or Aspergillus sp. In the case of infection. Be aware: contamination, storage, growth on microscope slides or in stain preparations

54

Parasites

55

Casts:

Hyaline casts = precipitated protein

Cellular casts: These have distinct cells within the protein matrix - if the cells are of epithelial origin (i.e., not WBCs or RBCs), they are called epithelial casts..

Granular casts: As cells within the protein cast matrix break down, the cast becomes coarsely then finely granular.

Waxy casts: Waxy casts are the final stage of cast degeneration (usually originating from cellular and granular casts). Compared to hyaline casts, they are readily observable because they have a smooth appearance, no internal texture, and are more refractile than the surrounding urine.

56

57

Questions?

58