Urinalysis Flashcards
Define oliguria
Reduced urine production
Define isosthenuria
Urine of a concentration of 0
Define poikuria
Irregular passage of urine
Define Stranguria
Painful passage of urine
What is the function of the kidneys?
Filter out waste from the blood, regulate water in the body conserve proteins, electrolytes and other compounds that the body can use.
What is the normal volume of urine produced in cats and dogs?
1-2mls/kg/hr
Why is a urine sample beneficial?
Cheap, non-invasive, clients can do it themselves
A urine sample can direct the right way for more diagnostic tests. It can detect changes in other body systems . Can detect urinary dysfunction
What is the best case scenario for examining a urine sample?
Collected in the morning when the urine is most concentrated
It should be collected mid-flow to avoid contaminants
Ideally, the vulva or prepuce should be cleaned beforehand
It should be examined within 1 hour of collection
What equipment is needed for all types of urine sample
PPE
Clean collection tray/ tube or non-absorbant litter
Sterile sample pot - plain or boric acid (bacteriology) - labelled
Needle and syringe, clippers and skin scrub
Ultrasound machine
Catheter and sterile lube
What equipment is needed to place a urinary catheter?
- Urinary catheter
- Gloves
- Swabs and antiseptic
- Water-based lubricant
- Kidney dish to collect urine
- Speculum and pen torch (needed in females)
- sterile water, needle and syringe
- Urine collection bag ( and bung for closed bag)
- Suture material and tape
Describe the procedure of placing a urinary catheter
- Prepare equipment
- Get someone to restrain patient (sedation may be req)
- Wash hands and use PPE
- Clean area with antiseptic (may also need to clip)
- May need to use speculum and pen torch to see at this point
- Analgesic gel or lube with analgesic properties onto the catheter end
- Insert the catheter gently into the urethra (no touch method best where catheter comes straight out of bag and into urethra without being touched by gloves)
- Stop inserting when urine flows down the catheter (be careful not to go too far as may just be no urine in bladder)
- Fix in place if indwelling
What are some of the conditions that can cause urinary problems?
Renal disease/failure Dehydration Bladder rupture Diabetes mellitus Feline Lower Urinary Tract Disease
What are the advantages of collecting a free flow sample?
Non-traumatic Owners can do it at home Quite sterile in mid flow - esp cats Easy to do Good sample to do for haematuria tests as no iatrogenic element
What are the disadvantages of collecting a free flow sample?
Patient awkward
Urethral contamination
Contamination from collection vessels e.g. litter tray
What is manual expression urine sample?
Gently palpating the bladder - patient normally in lateral recumbency.
It should never be used in cases with urethral obstruction!
What are the advantages of manual expression?
Easy to perform
What are the disadvantages of manual expression?
Can cause bladder rupture/ trauma
Non-sterile
Uncomfortable for patient
Must be sufficient urine in bladder
What are the advantages of placing a urinary catheter?
Fairly sterile
Relatively easy to perform
Can introduce contrast media via catheter
Can be indwelling for monitoring urinary output
Helps avoid scald in recumbent patients
Can use to empty bladder pre-surgery
What are the disadvantages of placing a urinary catheter?
Cost Risk of iatrogenic haematuria/trauma Tricky in bitches May need sedation or GA Iatrogenic infection
What position for urinary catheter patient is a male dog, male cat and females in?
Male dog - lateral recumbency or standing
Male cat - dorsal or lateral recumbency
Females - sternal recumbency with legs hanging off table
What is a cystocentesis. Describe procedure
Where a sterile needle (20-22G 1-1.5inches) is passed through the abdominal wall into the bladder at a 45 degree angle , aspirate a sample from the bladder and then pressure is applied to stop the bleeding.
Clip and use surgical scrub - strict asepsis is needed!
What are the advantages of cystocentesis?
Relatively quick way to obtain a sterile sample
Patient generally tolerate well without GA
Sterile
Fairly painless
No urethral contamination
Iatrogenic infection uncommon
What are the disadvantages of cystocentesis?
Difficult technique - usually a VS
Contraindicative in extreme bladder distension
May require sedtion/ GA
Must be sufficient urine in the bladder for it to be effective
Can cause blood contamination of the sample
Risk of peritonitis (can cause leakage of bladder into the abdomen)
How long can urine be kept before examination?
1hr or 6hrs if refrigerated (warm to room temp before testing)
What is the concern when refrigerating crystals?
Refrigeration can cause formation of crystals which will interfere with microscope examination of the sediment
Urine should NEVER be frozen
Why is boric acid used in some containers?
The sample should be put into a boric acid container if its going for bacteriology.
The boric acid in the container prevents further growth of bacteria and preserves the existing bacteria
What is the normal odour of urine ?
Sour
What are the different smells of urine caused by?
Male cats have a much stronger smelling urine as they scent mark with pheromones)
Ketonic urine smells like pear drops (acetone smell) - can indicate diabetes mellitus
Some bacteria can change smell e.g. like ammonia-smelling
Foul smelling can indicate excess protein
What makes the urine more viscous?
An inflammation in the urinary tract will give rise to urinary muco-proteins which makes the urine more viscoid (sticky)
What colour is normal urine?
Pale yellow
What does clear urine indicate?
Dilute
Polydipsia/polyuria
What does dark yellow urine indicate?
More concentrated
Dehydrated
What does Green urine indicate?
If there is also foam on the surface it indicates biliverdin (oxidation of bilirubin)
What does brown/red urine indicate?
Haematuria or certain drugs can also cause this
What does blue/green urine indicate?
Some drugs alter the colour of urine as does some foods e.g. beetroot
Why does normal urine go cloudy on standing?
Because microorganisms decompose the urea to ammonia which increases the pH and causes precipitation of phosphate.
Why is rabbit urine cloudy?
Due to the presence of calcium carbonate crystals
Name some things that can affect the turbidity of urine
RBCs Crystals or casts Cells Yeast Fungi Pus Phosphate precipitation Prostate/vaginal secretions
What is the specific gravity?
The weight of a known volume of fluid compared to the same volume of distilled water (SG of 1.000). It is an estimation of the concentrating ability of the kidney
What are the normal SG values for dogs and cats?
Dog: 1.015-1.045
Cat: 1.020-1.040
What can cause a decrease in SG? (i.e. less concentrated)
Polydipsia Renal failure/dysfunction Diabetes insipidus IV fluids Corticosteriod treatment
What can cause an increase in SG? (i.e. more concentrated)
Dehydration Acute Renal failure Diabetes mellitus Shock Sediment e.g. crystals Haemorrhage
Name 2 ways in which SG can be measured
- Dipsticks
2. Refractometer
Why is a dipstick not a completely accurate way of measuring SG?
It will only measure up to 1.030
How does a refractometer produce a SG reading?
It measure the change in refractive index due to substances dissolved in the fluid. The greater the refractive index the higher the SG
What should you check/ensure when using dipsticks
Stored correct
Not Damp
In date
Use fresh samples of urine (not in sun or fridge)
Why should urine samples be kept out of sunlight?
Can cause the oxidation of bilirubin and lower the results
What is the normal value for glucose in the urine of cats and dogs?
0
What might cause an increase in glucose in the urine?
- It occurs when glucose levels increase past the renal threshold Stress Excitement Hyperthyroidism Diabetes mellitus Cushings disease After dextrose-saline infusions
What is haemoglobinuria?
lysed blood in urine
What would cause Hb in urine?
Haemolytic anaemia, poisoning…
What would cause myoglobin in urine?
Muscle wasting diseases
What may be the cause of haematuria?
Cystitis Oestrus Urolithiasis Infection Acute nephritis Trauma to UT Warfarin poisoning
Define Bilirubinuria
presence of jaundice and bilirubin in the urine
What are the normal levels of bilirubin in the urine of cats and dogs?
Dogs: it is normal to have a trace element
Cats: 0
What does an increase in bilirubin in urine indicate?
Liver disease
Haemolytic jaundice
What is the most accurate test for bilirubin in urine?
Using a reagent table with diazo-reagent
- place urine on supplied pad
- place the tablet on the pad
- place 2 drops of water in top of the tablet so It runs down the pad
- if the area around the tablet turns blue then there is bilirubin present
Are ketones usually present in dog and cat urine?
No
What would ketouria indicate?
Abnormal and excessive breakdown of fat
What do ketones cause
They are toxic and can cause CN depression and acidosis (build up of acid in blood). A build up of ketones can lead to coma/death
What would cause ketouria?
Diabetes mellitus
Starvation
Liver damage
What is the first thing you should do if a patient presents with ketoacidosis?
IVFT!
What is urobilirubin?
Bilirubin that has been broken down by bacteria (intestinal)
Is urobilirubin normal in dog and cat urine?
A small trace amount may be normal in both
What can alter the level of urobilirubin ?
Liver dysfunction
Haemolysis
Hepatocyte damage
Should bile salts be present in cat/dog urine?
No
Is protein normal in cat/dog urine?
A small trace may be normal
(can be influenced by when the animal was last fed and collection method).
Mid-flow collection and manual expression may contain more protein due to urogenital secretions
What would an increased level of protein indicate?
Renal failure
Haemorrhage
Inflammatory disease
What is pH?
A measure of the free hydrogen ions .
High levels of h+ ions means a low pH
What is the normal pH of cat and dog urine?
Dog: 5-7
Cat: 7-9
What can cause urine with increased pH?
Stress/excitement alkalosis high fibre diet UTI Urine retention
What can cause a decreased pH of urine?
Fever Starvation High protein diet Acidosis Excessive muscular activity certain drugs
What are the centrifuge specifications for urine?
1500rpm for 5 minutes
How can a urine sample be viewed under the microscope at x100 oil immersion?
Prepare a slide with dried smear of sediment and stain with either Gram stain (for bacteria) or Giemsa (for cell study)
What are the parts of a urine sample called once its been centrifuged?
The sediment at the bottom and the supranate on top
What are casts and where are they formed?
Formed in the lumen of the distal tubules and collecting ducts of the kidneys where the concentration and acidity are the highest.
They are composed of a matrix of proteins from plasm and muco-protein excreted by the tubules
They are classified by their appearance
Describe hyaline casts?
Composed of protein
Cylindrical clear colourless
Indicate milk inflammation in the tubules, poor circulation
What is a cellular cast?
A number of different cells may be incorporated in to the cast e.g. RBCs (indicate haemorrhage into tubules) Leucocytes (indicate inflammatory reaction) Epithelial cells (indicate acute renal failure)
Name the 5 types of cast
Hyaline Cellular Granular Waxy Fatty
Describe granular casts
Can be coarse or fine
hyaline casts filled with granules (degenerated cells)
Seen in sever kidney damage/renal failure
Describe waxy casts
Have square ends as opposed to rounded ends
Wider than hyaline casts
Colourless/grey
Indicate sever degeneration of the renal tubules
Describe fatty Casts
Contain small droplets of fat
Can be seen in cats with renal disease and dogs with diabetes
Large numbers indicate degeneration of tubules
When would you find crystals in urine?
Can be in normal urine - especially if allowed to stand
Can also be associated with cystitis, urolithiasis and haematuria
Name the 4 crystals that can be found in acidic urine
Cystine
Calcium oxalate dihydrate
Ammonium urate
Uric Acid
Describe Cystine crystals
50p
Indicates renal tubule dysfunction
Describe Calcium oxalate dihydrate crystals
Small square crystals with an ‘x’ in the centre
- can also be found in neutral urine
Certain breeds are predisposed e.g. yorkies
Antifreeze poisoning can increase these crystals
Describe ammonium urate crystals
‘thorn-apple’ shaped - i.e. spikey balls
Found in neutral and acidic urine
Can indicate porto-systemic shunt / liver damage
Common in normal dalmation urine
Describe Uric acid crystals
Diamond or rhomboid shaped
Quite rare in dogs and cats (except dalmations)
What Crystals may be found in alkaline urine?
Struvite
Calcium phosphate
Describe struvite crystals
Coffin lid shaped
Describe Calcium phosphate crystals
Rectangular, flat and long
Quite rare
What other crystals are normally found in horse and rabbit urine?
Calcium carbonate crystals
What do crystals clump together to form?
Calculi
What are calculi called if they are present in the bladder?
Cystic Calculi
What are calculi called if they are present in the urethra?
Uroliths
What are uroliths?
Stones made of crystals found in the urethra
What effect can uroliths have?
The may cause irritation to the bladder lining or block the urethra
What normally causes blockages in a cats urethra?
‘Bladder sand’ - where the crystals collect and compact in the urethra rather than forming solid ‘stones’
What should be done before treating uroliths?
Chemical analysis of the uroliths
Describe the process of taking a urine specific gravity?
- Wear gloves
- Place distilled water onto the prism to check that it is accurate and calibrate the refractometer to 1.000 on the USG scale by looking down the eyepieces towards a light source.
- Dry the refractometer prism and place a drop of freshly mixed urine on the face of the prism
- Close the lid and hold up to the light source, adjust the focus and read the reading of where the blue and white meet
- Clean the refractometer with water
- Dispose of used materials and appropriate waste
