Urine - Gross and Chemical Exam Flashcards
Hilus
Indented part of kidney where vessels, nerves, and ureter enters/leaves
Renal Pelvis
Funnel-like beginning of the ureter
Nephrons
Part of kidney that does the work
* renal corpuscle
* proximal convoluted tubules
* loop of Henle
* distal convoluted tubules
* collecting tubule
Renal Corpuscle
Glomerulus surrounded by Bowman’s capsule
Flow and Production of Urine
- Blood enters glomerulus
- Plasma with waste filtered by PCT
- Moves through nephron and is modified
- Collecting tubules (now urine)
- Renal pelvis
- Ureter
Define
Anuria
No urine formation
Define
Cystitis
Inflammation of urinary bladder
Define
Dysuria
Difficult or painful urination
Define
Glomerular Filtrate
Fluid that passes from the blood through the glomerulus
Define
Glomerular Nephritis
Inflammation of the kidney without infection
Define
Hematuria
Blood in the urine
Define
Hemoglobinuria
Hemoglobin in the urine
* will not show intact RBC
* see with autoimmune disease
Define
Isosthenuria
- Urine with “fixed” SG similar to plasma and glomerular filtrate
- 1.010
- Kidneys have neither concentrated or diluted
- Frequently seen in animals with chronic renal disease
Define
Myoglobinuria
Myoglobin in the urine
* protein from muscle breakdown
* brown urine that won’t spin out
* see with DIC as well
Define
Nephritis
Inflammation of the kidney
Define
Oliguria
Decreased urine volume
Define
Polyuria
Abnormal increase in urine volume
Define
Pyelonephritis
Inflammation of the kidney with bacteria
Define
Pyouria
Pus in the urine
Pollakiuria
Frequent urination
Methods of Urine Collection
- Void
- Manual expression of bladder
- Catheterization
- Cystocentesis
Voided Urine Collection
Advantages
- Easy
- Fast
- Noninvasive
Voided Urine Collection
Disadvantages
- Nonsterile
- Can’t be used for bacterial exam or culture
Manual Expression of Bladder Urine Collection
Advantages
- Used for back neurological damage
- Done with sedation/anesthesia
Manual Expression of Bladder Urine Collection
Disadvantages
- Nonsterile
- Animals object
- Possible bladder rupture or trauma leading to hematuria
Catheterization Urine Collection
Advantages
- Decreased amount of contamination
- Preferred for urinary tract obstructions
- Easiest in male dogs
Catheterization Urine Collection
Disadvantages
- Not completely sterile
- Trauma to urethra/bladder
- More difficult in cats and female dogs
Cystocentesis Urine Collection
Advantages
- Preferred for microbiology
- Quick
- Most animals tolerate
- True urinary bladder sample
Cystocentesis Urine Collection
Disadvantages
- Need a fairly full bladder
- Skill required to perform
Handling Urine Samples
- 1st AM sample best - most concentrated
- Run within 30 minutes of collection
- Refrigerate up to 6 hours
- Small amount of formaline can be used to preserve - do this AFTER chemical and gross exam
Changes to Urine Allows to Sit
- Decreased glucose and bilirubin
- Increased pH due to bacterial breakdown (urea to ammonia)
- Increased cloudiness and production of crystals, or existing crystals melt
- Casts disintegrate as pH changes
- Increased bacteria - gram negative rods double every 20 minutes
What is Included in Gross Urine Exams
- Color
- Transparency
- Odor
- Specific Gravity
- Volume
Normal Urine Color
Yellow to Amber
Pale Urine Color
- High fluid consumption
- Diuretic therapy
- Diabetes
- Cushings
Dark Urine Color
Dehydration
Pink to Red Urine Color
- Hemoglobinuria
- Myoglobinuria (muscle disease)
- Hematuria
Differentiate Red Pigmenturia
Centrifuge Urine
* Red Sediment = Hematuria
Red Supernatant - Look at Plasma Color
* Clear = Myoglobinuria
* Red = Hemaglobinuria
Yellow to Orange Urine Collor
Increased bilirubin
Brown to Black Urine Color
- Bilirubin
- Methemoglobin
White Urine Color
Pyouria
Cloudy Urine Causes
- Amorphous phosphates
- WBCs
- Bacteria
- Mucous
- Fat
Causes of Odor in Urine
- Fruity: ketonuria
- Pungent/Ammonia: bacteria
- Not diagnostic, but can be helpful
Specific Gravity
- Density of urine compared to pure water
- Measures concentration and diluting ability of kidneys
- First function to be lost as a result of tubular damage
Normal SG
- No true “normal” value
- 1.003 - 1.035 average
- Dogs can go up to 1.060
- Cats can go up to 1.080
SG
Distilled Water
1.000
High vs Low SG
- High = Dehydration / Shock
- Low = Renal Disease, Diuretics, PU/PD
Azotemia
Increase in BUN / Creatinine within blood
Prerenal Azotemia
Reduced renal perfusion in dehydration / shock
* High SG
Renal Azotemia
Inability of tubules to concetrate or dilute urine
* isosthenuria
* 2/3 of kidneys are nonfunctional
Postrenal Azotemia
Blockage of urine output
Chemical Exam
pH
- Largely determined by diet
- Normal is acidic (less than 7)
- Alkaline in cystitis due to urea-splitting bacteria, or with urine allowed to sit due to bacterial action
Urine pH
Alkaline vs Acidic
pH is associated with the hydrogen ion concentration
* increased ions = acidic
* decreased ions = alkaline
Increased Acidity of Urine pH
Seen With
- Carnivores
- Severe diarrhea
- Starvation
- Diabetic ketosis (ER!)
Increased Alkalinity of Urine pH
Seen With
- UTI
- Renal failure
- Herbivores
Chemical Exam
Protein
- Trace is ok
- If proteinuria, but no infection - problem is glomerular origin
Chemical Exam
Glucose
- Blood glucose threshold is 180 mg/dL (dogs) and 300 mg/dL (cats)
- Above this, BG spills into urine
- Glycosuria can occur with reduced reabsorptive capabilities - predisposes to bacterial cystitis
- Glycosuria may not be detected with prolonged urine due to bacterial metabolism
Chemical Exam
Bilirubin
- Some ok in dogs
- Any in cats is significant - higher threshold
- Can be broken down in sunlight / artificial light
- Can indicate liver disease
- Confirm dipstick positive with Ictotest (more sensitive)
Chemical Exam
Leukocytes
Completely unreliable in animals
* cats will always have false positives
Chemical Exam
Ketones
- Found when fat metabolism replaces carbohydrate metabolism for energy
- Occurs with starvation and diabetes
- Can be lost with air exposure - test urine immediately
Chemical Exam
Urobilinogen
- Produced in intestine by bacterial reduction of bilirubin
- Indicates that bile duct is partially open
- Absence indicates bild duct obstruction
- Test is low sensitivity - little interpretive value
