29 notecards = 8 pages (4 cards per page)
Lipid-soluble pigment in plasma excreted in urine at a constant rate. Gives urine its yellow color.
If specimen is exposed to light, urobilinogen will oxidize and turn orange-brown.
Pink pigment, most evident when it deposits on urate crystals, producing a precipitate often described as brick dust.
By-product of hemoglobin catabolism and has characteristic yellow color. If significant, can give urine an amber color
If specimen is improperly stored, bilirubin will oxidize and cause the urine to turn greenish color
Used to treat UTI's gives urine a distinctive yellow-orange (orange soda pop) color. May interfere with the color interpretation on the chemical reagent strip
Alkaline urine (produces a white or beige precipitate)
Amorphous Urates (and uric acid crystals)
Acidic urine (produces a pinkish precipitate "Brick dust")
Urine on standing becomes odorous due to bacterial conversion of urea
Produce sweet or fruity smell
Normally 94% water and 6% solutes
Quantity of solutes present in volume of urine excreted
Expressed as specific gravity or osmolality
Ratio of urine density to density of an equal volume of pure water under standard conditions. Affected by number of solute particles and molecular size
Reagent Strip Method
Indirect colorimetric estimation of urine density based on amount of ionic or charged solutes present. Nonionic solutes such as glucose, urea, protein, or radiographic media are not measured
Indirect method based on refractive index of light. Affected by wavelength of light used, Temperature, and concentration of solution.
Reagent strip principle
Impregnated with polyelectrolyte and pH indicator at an alkaline pH. Released protons change pH of test pad. resulting in a color change.
SG reads above 1.040
Suspect radiographic contrast media or another large molecular weight solute
Concentration of solution expressed in terms of osmoles of solute particles per kilogram of water
Normal urine osmolality
275 to 900 mOsm/kg
depends on diet, fluid intake, and physical activity
Normal serum osmolality
275 to 300 mOsm/kg
Remains relatively constant
Principle uses of osmolality
Normal urine volume
600 to 1800 mL/day
Inability of kidneys to change specific gravity of plasma ultrafiltrate (which is 1.010)
Excretion of greater than 3 L/day
Excretion of less than 400 mL/day
Complete lack of urine excretion
SG range for urine
1.002 to 1.035
Density of urine / density of equal volume of pure water