Urinalysis Flashcards
When should u+ be examined
As soon as possible
Within 60 mins fresh, or refridgerate then allow to come back to room temp before analysis
Longer age of u+ = higher pH, degeneration of cells and casts, dissolution and precipitation of casts, bacteria multiply, decrease in glucose and ketones
How may infection alter pH
Increases it
Outline the protein measurement on dipstick
Small amount normal, can get false positives if the pH is high
Only albumin so will miss things like bence jones proteins
What can cause false readings on the blood measurement on dipstick?
bleach and bacteria
What can cause a +ve on the blood measurement on dipstick?
UT disease
Genital tract disaese
Prostate disease
coagulopathy
Outline the leukocyte measurement on dipstick
If negative means nothing
If +ve in dogs is significant
Cats can get false +ve
How can you get a false +ve glucose measurement on dipstick?
Bleach/ from containers
Also from drugs - asprin/ morphine/ vitamin c/ cephalosporins
False -ve - from fridge samples
Whaat does glucosuria mean?
If also high in blood - DM or stressed cat or exogenous/ endogenous steroids
If normal in blood - fanconi syndrome or primary renal glucosuria
What can cause high ketones measurement on dipstick?
Diabetic ketosis
starvation
high T4
Can just be if the sample is very concentrated
What must you be careful with with measuring ketones on dipstick with DKA?
In severe cases it is main bHB that is produced, this is not measured on the dipstick, only acetoacetate.
So as patient improves their ketone levels on dipstick may increase
On sediment, what does a lot of RBCs without lots of WBCs suggest?
Haemorrhage without significant inflammation
e.g. Neoplasia
Trauma
Coagulopathy
What may bacteria in sediment without inflammation suggest?
May be precipitate/ contamination
May also occur in cushings and renal disease - ideally culture
When do granular casts occur?
nephrotoxicity
Ischaemia
Haemoglobinuria
Small amount may be normal
When are crystals more likely to be significant?
If examined within 60 mins of sample collection
Dilute urine
Blood or WBCs present
Suggestive clinical signs
Outline struvite stones/ crystals
Coffin lid shape, colourless radio-opaque magnesium ammonium phosphate Alkaline pH Can occur in infection due to urease producing bacteria, can also be in sterile u+ UTI ones with dogs, sterile with cats normally f>m Can be normal Stones are round, smooth and dense Staph/ e.coli/ klebsiella/ proteus
Outline calcium oxalate crystals
Neutral to acidic urine Colourless Envelope shape (dihydrate) Monohydrate are longer in shape, occur in antifreeze poisoning Need surgery to remove uroliths Radio-opaque Stones can cause a UTI Males more than females Dogs that urinate less are more at risk of stones Stones are round to oval, smooth or rough
Outline calcium phosphate aka apatite
Radio-opaque Neutral to weakly acidic or alkaline urine Can be normal Can be due to underlying hypercalcaemia 1-2% uroliths Pure or minor component of Ca Ox or struvite Lots of forms reported More in kidneys than the bladder
Outline Ammonium urate
Common in dalmations and English bulldogs, also russian terrier, mini shnauzer, Shih Tzus, yorkies
In other breeds should look for liver disease or PSS
Stones lucent or only barely visible
In acid urine
stones are smooth round to oval
cats can get idiopathic ones
Outline bilirubin crystals
Can be normal in dogs, not cats
can suggest liver diease
acidic urine
N.B the dipsticks are more sensitive to conjugated bilirubin than unconjugated bilirubin
Outline cholesterol crystals
Rare
Neutral to acidic urine
Can be normal but can be due to a PLN
Outline cystine crystals
Rare
Hexagons
Acidic urine
Seen in Mastiffs, EBDs, dachshunds, chihuahuas due to abnormal metabolism. Autosomal recessive in newfoundlands, can occur v early
Stones radiolucent with slightly irregular shape
Crystals predisposing but not a cause
What is UPCR?
Urine protein divided by urine creatinine
Quantifies protein loss
Only useful if there is no sediment
>0.5 in dogs and >0.4 in cats = abnormal
Outline microalbunuria
Newish test, can be an early indicator of renal disease but can also go up with other issues.
How can you tell what is causing brown red or black urine?
If the urine is discolored because of myoglobin, the plasma is clear because myoglobin in plasma is not bound significantly to a carrying protein, which results in filtration and excretion of myoglobin.
If the plasma is pink, it is suggestive of haemoglobin. If the plasma is yellow, it is suggestive of bilirubin; serum bilirubin concentration should also be increased.
What do haemoglobinuria/ myoglobinuria/ bilirubinuria mean?
Myoglobinuria indicates muscle damage; serum creatine kinase activity is often increased Hemoglobinemia indicates intravascular hemolysis resulting from immune-mediated, parasite-mediated, or drug-mediated destruction of RBCs. Hyperbilirubinemia may result from liver disease, post–hepatic obstruction, or hemolysis.
What does milky white urine suggest? How can you differentiate the causes?
presence of WBCs (pyuria), lipid, or crystals.
Examine the sediment
What are the differentials for proteinuria?
prerenal (fever, strenuous exercise, seizures, extreme environmental temperature, and hyperproteinemia)
renal (primarily glomerular and occasionally tubular disease),
postrenal (inflammation, hemorrhage, and infection)
How many WBCs should be seen phpf?
Normal urine should contain less than 5 WBCs per field at 400× magnification
How many RBCs should be seen per hpf?
Normal urine should contain less than 5 RBCs per field at 400× magnification
What are hyaline casts?
pure protein precipitates transparent have parallel sides and rounded ends, composed of mucoprotein. They may occur with fever, exercise, and renal disease, odd one can be normal
Which casts are always abnormal and what do they mean?
erythrocyte casts and WBC casts
Erythrocyte casts form because of renal hemorrhage. WBC casts occur because of renal inflammation, as with pyelonephritis.
What is Brownian Motion?
Random movement of the granules in a neutrophil - can be mistaken for bacteria
Outline granular casts
degraded cellular material from injured renal tubular epithelial cells or, less often, inflammatory cells, embedded in a protein matrix.
Nephrotoxins (e.g., gentamicin sulfate, amphotericin B), nephritis, and ischemia are pathologic events that result in their formation.
How are struvites formed in a UTI?
More tha 50% fo stones are struvite
Almost always due to a UTI in dogs
Urease split to urea and bicarb
Urea to ammonia to ammonium = increase in pH as loss of H+
lower H+ –> increased production of phosphorous which combines with Mg
Bicarb –> increased pH = lower solubility of struvite
Ammonium leads to damage of urothelial GAG coating which allows bacteria and struvite to attach
This leads to the promotion of the formation of an organic matrix leading to struvite stones
when disolving, bacteria can be trapped in stones leading to the cycle again
Outline the process of purine to allantoin
Purine to hypoxanthine through xanthine oxidase, to xanthine through XO again to uric acid through uricase, to allantoin
Why are dalmations predisposed to urate calculi?
Decreased conversion of uric acid to allantoin
Increased uricosia d/t decreased tubular absoprtion
males more than females
Average age 4.5, decreasing chace with age
Autosomal recessive
What can cause urate stones?
Urease bacteria = ammonium, which predisposes to urate calculi formation.
needs low pH
Low protein diet - poor hepatic function - increased uric acid
Poor hepatic function (MD, pSS, cirrhosis)
outline xanthine uroliths
Tx with allopurinol, diet high in purine
Hereditary in dachshunds and CKCS
