Week 7: Intro to UA
• Urinalysis
• Renal anatomy and
• Physical properties of
physiology
• Nephron anatomy
• Urine collection and
preservation
Color
Appearance
Specific gravity
Volume
Odor
Foam
urine
•
•
•
•
•
•
Urinalysis
• One of the oldest “lab”
procedure
• Diabetes mellitus vs
diabetes insipidus
• Examination of urine
samples
• Physical properties
• Chemical components
• Microscopic sediments
Renal Anatomy
• Kidneys
•
•
•
•
•
•
•
•
Renal artery and vein
Medulla
Cortex
Calyx
Ureter
Bladder
Urethra
Adrenal glands
Nephron
•
•
•
•
•
Functional unit of kidneys
About one million per kidney
Concentrate urine
Filter blood
Excrete waste products
Nephron
Anatomy
• Afferent and efferent
•
•
•
•
•
•
arterioles
Glomerulus
Bowman’s capsule
Proximal convoluted
tubules
Loop of Henle
Distal convoluted
tubules
Collecting duct
Nephron Function
• Ultrafiltration of blood
• 180 L/day of blood filtered
• >80% reabsorbed
• Antidiuretic hormone cause another 20%
absorption
• 1-2 L/day urinary output
• Reabsorption of minerals and nutrients
• Active secretion of waste
Antidiuretic Hormone ADH
• Also called vasopressin
• Made in hypothalamus and secreted from posterior
pituitary
• Increases porosity in distal tubule and collecting
duct
• Lack of ADH result in d. insipidus
• Unable to concentrate urine (isosthenuria):
constant specific gravity at 1.010
Normal Urine Contains…
• Urea from ammonia and
CO2
• Uric acid from DNA
metabolism
• Creatinine from muscle
• Electrolytes
Urine Collection
•
•
•
•
•
•
•
•
•
Random
12 hour or 24 hour timed
First morning void
Clean catch
Mid-stream
Fasting
Postprandial
Urethral catheter
Suprapubic aspiration
Decomposition of Urine
• Bacterial growth
• Ammonia or acid
•
•
•
•
formation
Change in pH
Ketone evaporate
Urobilinogen oxidized
Bilirubin degradation
with light
• Crystals
• Cells and casts lyse
• Change in color
• Alkaptonuria
• Change in specific
gravity
Urine Preservation
•
•
•
•
Refrigeration up to 8 hours
Thymol to prevent bacterial growth
Formalin to preserve cells
Acid or base to preserve compounds
More Terms to Study
•
•
•
•
•
Polyuria
Oliguria
Anuria
Dysuria
Hematuria
•
•
•
•
•
Glycosuria
Proteinuria
Bacteriuria
Cylindruia
Hemoglobinuria
Color
•
•
•
•
•
•
Normal: shade of yellow (straw to amber)
Urochrome, uroerythrin
Yellow due to bile in jaundice
Red due to Hb or myoglobin
Black in alkaptonuria after light exposure
Other color due to medication
Appearance
• Normal: clear to slightly hazy
• Cloudy to turbid due to microscopic
sediments
• White and red cells
• Bacteria and yeast
• Crystals
Specific Gravity
• Normal: 1.015 - 1.025 (wider range with
•
•
•
•
random collection)
Urinometer: true reading of specific gravity
Refractometer: use light refraction by
dissolved substances
Reagent strip: ionic concentration
Osmometer: most accurate measurement of
total dissolved substance
Refractometer vs Dipstix SG
• Refractometer measures dissolved
substances
• Each gram of glucose raises SG by 0.004
• Each gram of protein raises SG by 0.003
• Correction gives more accurate measure of
kidneys’ concentration ability
• Reagent strip measures ionic concentration
• Urinary waste will ionize so good measure of
kidneys’ ability to concentrate
• Non-ionizing substances: glucose, protein, IVP
Other Information…
• Volume: 600 - 1,600 mL
per day
• For timed collection only
• Foam: white
• Yellow due to bile in
hepatitis
• Excessive due to
proteinuria
Other Information…
• Odor: faintly aromatic
•
•
•
•
Foul due to bacterial growth
Fruity due to ketones
Maple Syrup Urine Disease
Other due to food or medication