clin chem urinalysis- collection, macro eval

nephron

functional unit of the kidneys

nephrons are responsible for

• filtration

• reabsorption

steps of urine formation

1. filtration of substances from the glomerulus to bowman’s capsule

2. reabsorption of of substances from the renal tubules to the blood stream

3. storage/excretion from urinary bladder

degree of filtration is dependent on?

• blood pressure (anesthesia lowers)

• amount of blood reaching the glomerulus (shock lowers)

• follows the laws of diffusion

freely filtered substances

• water

• electrolytes

• glucose

• amino acids

• BUN and creatinine

BUN and creatinine are?

non protein nitrogenous waste

BUN stands for?

blood urea nitrogen

urea comes from?

protein breakdown by ammonia

creatinine comes from?

muscle metabolism

what factors control reabsorption?

• hormones

• blood levels

what hormones can control reabsorption?

• ADH - tells renal tubules to reabsorb water

• aldosterone- controls Na + Ca reabsorption and K excretion

cause of glucosuria

• blood level of glucose is above the renal threshold

  • glucose filtered will not get reabsorbed back into blood stream

normal blood glucose for dogs

100 mg/dl

renal threshold for dogs

160-180 mg/dl

advantages of an early morning urine sample

• most likely to show urine concentration (has no water intake)

• increased chance of observing abnormalities like crystals

disadvantage of early morning sample

• poor cytology sample because urine has been sitting awhile

advantage of recently formed / pm sample

good for cytology because of fresh urine

disadvantage of recently formed/pm sample

may not show urine concentration (sample might be dilute)

why is dilute urine not good for urine concentration?

• chances of observing abnormalities are low

• is a hypotonic solution, can cause cells to swell and rupture (rbc lysis)

advantage of free catch collection

• easiest on the animal

• no iatrogenic trauma/infection

• client can do it

disadvantage of free catch collection

• may need sample now but animal wont go

• not the best for culture because of contamination

advantage of manual expression collection

when pt is under anesthesia prior to spay or laparotomy can get the bladder out of the way

disadvantages of manual expression

• may require anesthesia

• difficult on big dogs with tense abdominal muscles

• may cause iatrogenic trauma/infection to bladder

• can rupture bladder

• if pt has cystitis can drive bacteria up ureters and cause pyelonephritis

advantages of catheterization

• can usually get sample right away

• can relieve obstruction

• if using a foley, can monitor urine output

disadvantages of catheterization

• iatrogenic trauma/infection

• may require anesthesia

advantages of cystocentesis collection

• best method

• can get sample right away

• does not require anesthesia

• best method for culture

disadvantages of cystocentesis

iatrogenic trauma/infection

position of female dog for cystocentesis

dorsal recovery

size syringe used for a cysto

6 cc or 12 cc

what happens when urine sits at room temp

• over time bacteria multiply

• crystals increase in number

• urine gets cloudy

• cells disintegrate

• casts breakdown

• ph changes (typically increases)

urine can be refrigerated

up to 6 hours

4 parts of a routine U/A

• macroscopic eval

• USG

• urine chemistries

• microscopic evaluation

urinalysis

determines function of kidney and other organs (pancreas (glucose), liver (bilirubin))

parts of the macroscopic evaluation

• color

• clarity/transparency

• odor

• foam

Normal urine colof

Straw(pale yellow) - amber(dark yellow)

Reasons for discolred urine

• Hematuria

• Hemoglobinuria

• Myoglobinuria

• Bilirubinuria

• Pseudomonas, drugs

Hematuria

Blood (rbc’s) in urine. Red-reddish brown color

Hematuria causes

• Inflammation

• Trauma

• Urolithiasis

• Neoplasia

• Coagulopathy

• Rough cysto, catheter, or manual expression

Hemoglobinuria

Hemoglobin in urine. Red-reddish brown, transparent.

Hemoglobinuria causes

• AIHA

• Incompatible blood transfusions

• Toxins/poisons/snake venom

• Rbc parasites

Myoglobinuria

Myoglobin in urine. Red-reddish brown, transparent,clear plasma.

Myoglobinuria causes

Occurs with muscle cell lysis.

• Exertional rhabdomyolysis (monday morning sickness)

• Extree muscle exertion

• Crushing injuries

• Heat stroke

• Electric shock

• Snake bites

Bilirubinuria

Bilirubin in the urine. Dark yellow-yellow orange-yellow brown-green.

Bilirubinuria causes

• Excessive hemolysis

• HBO

• Liver disease

Options for recording clarity/transparency

• Clear/transparent

• Hazy

• Cloudy/turbid

• Opaque

• Flocculant

Carnivores normal clarity

• Clear/transparent

• Increased concentration =hazy

Odor-ammonia smell

May indicate cystitis due to urease pos bacteria

Odor- sweet and fruity

May indicate pseudomonas or ketones (DM)

Foam

Prescence may indicate increased proteins