Urinalysis

Question 1

sampling techniques for urinalysis

Answer 1

1. free catch sample
2. catheterisation
3. cystocentesis

Question 2

assessment of urine colour

Answer 2

• normal urine is clear and yellow to straw coloured
• very light yellow or very pale straw coloured
  
  • low specific gravity - i.e. very diluted
• deep yellow or orange
  
  • very concentrated urine
  • jaundice
  • effect of drugs
  • food sources
• dark yellow greenish
  
  • biliverdin
  • long term stasis or urine in urinary bladder
  • long storage of sample
• Red, yellow-reddish
  
  • haemoglobinuria, haematouria (mostly bacterial infections)
  • consumption of beetroot or red food dyes
• Dark red brown, chocolate
  
  • older haemoglobin
  • methaeglobin present ( babesiosis, paracetamol poisoning)
  • myoglobinuria (burns, mysitis)
• Blue
  
  • methylene blue (present in some drugs)
  • Multivitamins, B-vitamins, food dyes etc.
  • pyuria due to pseudomonas spp.
• Green
  
  • food sources
  • drug sources (propofol)
• cloudy or opaque
  
  • mucus - physiological in Eq
  • proteinuria
  • lipiduria - physiological in both dogs and cats
  • Pyuria
  • crystals or amorphous materials

Question 3

describe urine odour

Answer 3

• usually specific urine smell
• usually stronger in males
• lower urinary tract infections
  
  • ammonia smell
• ketoacidosis
  
  • sweet smell
• faecal contamination
  
  • faeces smell

Question 4

describe specific gravity

Answer 4

• it is an indicator of the concentrating abiity of the kidney tubles
• SG is the ratio of the weight of the liquid to an equal volume of distilled water

Question 5

how to measure SG

Answer 5

• urinometer (most accurate)
• refractometer
• test strip (least accurate)

Question 6

causes of hyposthenuria (reduced SG)

Answer 6

• tempory by increased water intake
• hyperadrenocorticism
• decreased ADH production
• ADH resistance
• renal tubular damage
• psychogenic polydypsia (PP)
• liver disease
• hypoadrenocorticism (loss of Na⁺)

Question 7

causes of isosthenuria

Answer 7

• tubules are not able to concentrate primary glomerular filtrate
• severe tubular damage

Question 8

Causes of hypersthenuria

Answer 8

• normally urine is hypersthenuric
• causes (pathological)
  
  • decreased water intake
  • substantial water loss
  • acute kidney failure
  • DM

Question 9

what is the normal urine PH

Answer 9

carnivores = 5.5 - 7.5

herbivores = 7.0 - 8.5

Question 10

causes of PH decrease

Answer 10

• ketosis (Ru)
• Lacticacidosis (Ru)
• abomasal displacement
• metabolic + respiratory acidosis - increase in H+ excretion
• in vomiting - Na⁺ is reabsorbed with HCO₃^- - urine becomes more acidic
• Hypokalaemia
• treatment with acidifying drugs
• toxicosis with acidifying substances - ethylene glycol
• distal renal acidosis

Question 11

causes of PH increase in the urine

Answer 11

• feeing in carnivores - acid secretion in the stomach
• UTI
• metabolic and respiratory alkalosis
• proximal renal acidosis - increasing HCO₃^- secreted into urine
• overloading of alkalizing substances - bicarbonate or lactate containing inusion
• long storage time causes urea decomposition to ammonia (increasing PH)

Question 12

tests for determing protein in the urine

Answer 12

1. test strips
2. sulphosalicylic acid test (better than test strips)
3. Heller test (G - melin test)
4. spectrophotometry method
5. urea: creatinin ration (UPC)
6. specific methods:

• immune electrophoresis
• western blot
• spectroscopy

Question 13

Pre renal causes of proteinuria

Answer 13

• Physiological
  
  • neonates before drinking of colostrum
  • excersise
  • exposure to extreme hot or cold
  • stress
• Pathological
  
  • Increased protein catabolism
  • fever
  • seizures
  • increase in blood pressure
  • Dysproteinaemias
  • haemoglobinuria
  • severe muscular injury - myoglobin

Question 14

causes or renal proteinuria

Answer 14

• glomerular damage
• specific tubulointerstitial lesions
• infectious diseases (babesiosis, erlichiosis)

Question 15

describe pseudoproteinuria

Question 16

describe the tests for pus in urine

Answer 16

• donne test
  
  • drip 4-5 drops of NaOH into urine sample
  • if pus is present then coagulation occurs
• microscopic evaluation

Question 17

causes of pyuria

Answer 17

• donne test in horses produces + result ( mucus not pus)
• kidney pelvis inflammation
• cystitis
• inflammation of the genital tract

Question 18

tests for blood in urine

Answer 18

• Benzidine test
  
  • high sensitivity but low specificity
  • add 0.5 - 1 g of benzidine powder and 0.5 - 1g H₂O₂ into a test tube and dissolve 2ml 30% acetic acid (haemolyse RBCs)
  • Haemoglobin reacts with H₂O₂
  • Free singlet oxygen reacts with benzidine to form deep green complex
• Urine test strip
• Urine sediment analysis

Question 19

causes of haematuria

Answer 19

• lower UTI
• Trauma (urinary bladder, kidney, urethra/ureter)
• geital tract injury
  
  • endometritis
  • prostatitis
  • hypertrophy of the prostate gland
• infectious and non infectious inflammatory processes in the higher and lower urinary tract
• Renal infarction
• Thrombocytopenia, coagulopathy

Question 20

causes of haemoglobinuria

Answer 20

• intravascular haemolysis
  
  • IHA
  • Babesiosis
• long term stasis of blood in the urinary bladder

Question 21

causes of myoglobulinuria

Answer 21

• excessive muscle trauma
• excercise
• ischaemia (aortic thromboembolism in cats)
• myositis
• burns

Question 22

causes of increased nitrite in the urine

Answer 22

• bacteria reduce nitrate into nitrite
• UTI
• False positives
  
  • old or unsterile samples
  • vitamin C and antibiotics
• test is unreliable in carnivores

Question 23

organic substances in the urine

Answer 23

• blood cells
• cells from the lower urogenital tract
  
  • transitional cells
  • squamous cells
  • sperm cells
  • tumour cells
• viral inclusion bodies - distemper etc.
• Microbes
• mucin
• fat droplets
  
  • normal in cats
• starch and pollen grain contamination
• casts
  
  • formed from mucoproteins produced by the renal tubular cells

Question 24

inorganic sediments found in alkaline urine

Answer 24

• struvite
  
  • presence or urease positive bacteria in UTI
• Calcium carbonate
  
  • hypercaluria
  • horses, high calcium diet in dogs
• calcium phosphate
  
  • hypercaluria
• amorphous phosphate
  
  • meat and grain in diet - usually no clinical significance
• Ammonium - ureate/biurate
  
  • severe impairment of hepatic function ( e.g. PSS)
  • in dalmation dogs

Question 25

inorganic sediments found in acidic urine

Answer 25

• oxalate crystals (needle like)
  
  • ethylene glycol poisoning
  • consumption of toxic plants
  • common in herbivores
• uric acid
  
  • Dalmations (congenital)
  • severe impairment of hepatic function (e.g. PSS)
• Cysteine, leucine
  
  • metabolic disease
  • liver failure
  • congenital defect of tubular resorption
• Biliruben crystals
  
  • pre hepatic and hepatic jaundice
• Sulphanamides
  
  • sulphanamide therapy