Urinalysis Flashcards
Sampling procedures
- Free catch sample
- Catheterisation
- Cystocentesis
Free catch sample - advantage and disadvantage
Adv: no restraint or sedation no special equipment done by owner Disadv: easily contaminated not to be used for microbiological culturing animal will not urinate if disturbed impossible to do with cat using a litter box
Catheterisation - advantage and disadvantage
Adv:
less contaminated (not to be used for microbiological culturing)
additional info for diagnosing urethra obstruction
sample even in bladder is empty
can measure volume over a period of time
Disadv:
special equipment needed
small animal females & large animal males are difficult
danger of transferring bacteria
risk of traumatic injury
small bleeding = false + for blood in urine
sedation needed sometimes
Cystocentesis - advantage and disadvantage
Adv: sterile samples not influenced by urethral or genital problems safe, no sedation Disadv: rare but trauma can occur minor bleeding cats have vagal stimulation = transient SX
Why must urine samples from horses be filtered before analysis?
They contain mucous and crystals that can disturb the analysis
Urine is yellow because of?
Urobilins. Specifically d-/i-/l- urobilin.
Normally, should be clear and yellow to straw coloured.
Horses may have turbid urine.
Very light yellow or pale straw colour urine indicates?
Low SG (specific gravity) Polyuria/ Polydipsia in diabetes mellitus or chronic kidney failure
Deep yellow / orange urine indicates?
Very concentrated Oliguria, dehydrated, acute kidney failure Jaundice = increased bilirubin content Drug effects Food sources
Dark yellow - greenish urine indicates?
Biliverdin
Stasis of urine due to blockage
Long storage
Red, yellow - reddish urine indicates?
Haemoglobinuria / haematuria
Food sources
Dark red brown, chocolate urine indicates?
Oxidized haemoglobin
Methaemoglobin present (babesiosis, paracetamol toxicosis)
Myoglobinuria (burns)
Blue urine indicates?
Methylene blue (drugs, vitamins, food dyes) Pyuria due to Pseudomonas spp. infection Genetic disease in humans
Green urine indicates?
Fod sources Drug sources (propafol IV)
Cloudy or opaque urine indicates?
Mucous Proteinuria ( kidney failure, exercise) Lipiduria Pyruria Crystals
Odour of urine
Varies among spp.
Stronger in male animals
In case of UTIs or retention = ammoniacal smell
Ketoacidosis = sweet, fruity, acetone like smell
Transparency of urine
Transparent in healthy animals (except Horses)
Opacity due to UTI, lipiduria or contamination from vaginal/preputial discharge
Specific Gravity of urine
Indicator of concentrating ability (tubular function) of kidneys
- Ratio of the weight of the liquid to an equal volume of distilled water
- Increases with increasing cc. of dissolved ions, glucose, proteins, lipids and contrast material
- Measured by urinometer, refractometer or test strip
Urinometer measurement - adv. and disadv.
Calibrated at room temp. Adv: most accurate not influenced by opacity Disadv: high amount of urine is needed (5-10ml / 30-50ml)
Refractometer measurement - adv. and disadv.
Calibrated with distilled water. Adv: One droplet of urine Disadv: not reliable if sample is not transparent
Test strip measurement - adv. and disadv.
Not useful in animals, unreliable
Physiological range of SG
Dogs: 1.015 - 1.040
Cats: 1.035 - 1.060
Can vary due to water intake and hydration status
Measurement essential if there is polydipsia and polyuria
Hyposthenuria (evaluation of SG)
SG < 1.008 (if persistent = pathologic) Hyper-/hypoadrenocorticism CDI - central diabetes insipidus NDI - nephrogenic diabetes insipidus Renal tubular damage PP - psychogenic polydipsia Decrease in urea synthesis Prolonged fluid therapy = medullary washout
Isosthenuria (evaluation of SG)
SG 1.008 - 1.012 (if persistent = pathologic)
Tubules cannot concentrate or dilute primary glomerular filtrate
Indicator of severe tubular damage
Medullary washout
CDI
NDI
PP
(A water deprivation test may be necessary)
Hypersthenuria (evaluation of SG)
SG > 1.012 (normal urine) Pathologic when: Decreased water intake Water loss (vomit, panting, sweating, diarrhoea) Acute kidney failure
Water deprivation test (WDT) goal
Assess concentrating ability of tubules, to differentiate between CDI, NDI and PP
WDT indications
Persistent PU / PD, more than 1 SG measurement classified as hyposthenuria
WDT contraindications
Severe endocrine disturbance (DM, Cushings, Addisons) Dehydration Uraemia Pregnancy UTI
WDT interpretation in case of PP, CDI and NDI
PP = SG > 1.025
CDI / NDI = SG < 1.010
1.010 - 1.020 values = equivocal / partial CDI
How to differentiate between CDI and NDI
Perform the DESMOPRESSIN TEST
SG > 1.015 = CDI
SG < 1.010 = NDI
In between = medullary washout
Urine pH in herbivores, carnivores and in renal compensation
Herbivores pH 7 - 8.5
Carnivores pH 5.5 - 7.5
Renal compensation pH 4 -8.5
What affects urine pH?
Diet
Recent feeding
Bacterial infection
Storage time
False low pH occurs when?
Due to contamination by acid from protein region of the test strip
False high pH occurs when?
Contamination due to detergents, bleach, disinfectants
Causes that DECREASE pH ( 7 POINTS )
Metabolic and Respiratory acidosis Vomiting Hypokalaemia Acidifying drugs Distal renal tubular acidosis Abomasal displacement Toxicosis of acidifying substances
Causes that INCREASE pH ( 6 POINTS )
Feeding in carnivores = slight metabolic alkalosis
UTI
Metabolic and respiratory alkalosis
Proximal renal tubular alkalosis
Overload of HCO3- or lactate containing infusion
Long storage time
Measuring methods of Proteinuria (8 methods)
1) Test strips = colour change, blue to green
2) Sulphosalicylic acid test = coagulates proteins, high sensitivity, not specific and does not differentiate types and causes
3) Heller test = Gmelin test, shows protein content as an opaque zone above biliverdin and urine
4) Spectrophotometric
5) UPC , info on severity, normal < 0.5, proteinuria > 1
6) Evaluate albumin / globulins
7) Determine Bence-Jones proteins = monoclonal immunoglobulins
8) Microalbuniuria
Pre-renal Proteinuria causes
Benign proteinuria: Occurs in neonates <40 hours of age Exercise Hypo-/hyperthermia Stress Pathologic proteinuria: Increased protein catabolism Fever Seizures Increased BP Haemoglobinuria
Real Proteinuria (nephrogenic)
Plasma proteins leak into the urine
When albumin is excreted = selective proteinuria
When IgG appear in urine = non-selective proteinuria
Difference in protein content in Acute and Chronic renal failure
Acute = high (inflammation, cc. urine) Chronic = low (polyuria, diluted urine)
Pseudo Proteinuria
Proteins detected originate from lower urinary or genital tract
Physiological after parturition
Normal in horses
Pathological in UTI, inflammation of testes/prostate, prostate/vaginal tumour
Pus in urine
Accumulation of neutrophil granulocytes, tissue cells and microbes
Called PYURIA when in urine
How to evaluate pus in urine
Donne test
Causes of Pyuria (pus)
Normal in Eq = positive result
Kidney pelvis inflammation
Cystitis
Inflammation of genital tract
Haematuria
Presence of blood
Intact RBCs in the urine
Hamoglobinuria and myoglobinuria
Presence of dissolved haemoglobin and myoglobin in urine
Benzidine test
Shows the presence of blood, haemoglobin or myoglobin
High sensitivity
Low specificity
Urine test strip
Speckled appearance = haematuria
Diffused colour = haemoglobinuria / myoglobinuria
Causes of haematuria (6)
UTI
Trauma
Genital tract injury, tumour or inflammation
Infectious / non infectious inflame. process of UT
Renal infarction
Thrombocytopenia, coagulopathy
Causes of Haemoglobinuria (2)
Intravascular haemolysis
Long term stasis of blood in bladder
Causes of Myoglobinuria (5)
Muscle trauma Exercise Ischaemia Myositis Burns
Renal threshold of Glucose
Dogs - 10 mmol/l
Cats - 14-17 mmol/l
When can Glycosuria be detected?
Hyperglycaemia (duh)
Renal tubular defects = decreased reabsorption capacity
Tested with urine test strips
Ketonuria
Ketone bodies not present in urine normally
Ruminants - screen for 1st and 2ndary ketosis
Small animals - seen in DKA and starvation
Use urine test strips
Nitrite
Urine test strips
UTIs
UNRELIABLE IN CARNIVORES, their urine contains no nitrates
Bilirubin and UBG
Conjugated bilirubin in healthy dog urine
Other spp only appears during jaundice
Urinary test strips or Gmelin test
Organic sediments found in Urine
1) Blood cells: normal < 5 / hpf, abnormal = haematuria
2) Cells from lower Urogenital tract : norm 0-2/hpf
- Urothelium cells
- Renal tubular cells
- Squamous cells from penis or vagina
3) Viral inclusion bodies
4) Microbes
5) Mucin : fat droplets normal in cats
6) Casts
Inorganic sediment found in Urine
Struvite crystals
Calcium crystals
Different types of crystalluria (alkaline urine)
- Struvite: UTIs
- Ca carbonate: hypercalcuria
- Ca phosphate: hypercalcuria
- Amorphous phosphate: meat and grain diet, cc urine
- Ammonium ureate/biurate: hepatic function f**d, for eg. dalmatians
Different types of crystalluria (acidic urine)
- Ca oxalate: toxic plants consumption in cates
- Uric acid: dalmatians
- Cystine: liver failure
- Bilirubin crystals: pre-/hepatic jaundice
- Sulphonamiddes: therapy
