urinalysis
TRANSCRIPT
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