Full cm

• URINE SPECIFIC GRAVITY

  Degree of concentration or dilution of the specimen

  • density of solution compared with that of density of

  similar volume of distilled H20 at similar temperature

  • specific gravity measures the concentrating and diluting

  abilities of the kidney.
• Random specimen Specific gravity

  1.015 - 1.030
• ↑ SG


  more concentrated
• ↓ SG


  diluted / less concentrated
• Urinometer, Refractometer, Harmonic Oscillation Densitometry


  Equipments used for measuring Urine Specific Gravity
• URINOMETER

  weighted float that displaces a volume of liquid equal to its weight
• Major disadvantage of Urinometer

  Major disadvantage: large volume (10-15 mL) and less

  accurate (Not recommended by CLSI )
• Refractometer

  Measures the refractive index → refers to the velocity of light in air with that of the solution
• Advantage of Refractometer

  No correction due to temperature changes (based on the calibration temperature) and less affected by CHO & CHON particle density
• HARMONIC OSCILLATION DENSITOMETRY


  Based on the frequency of sound waves entering to the solution that is proportional to the density of the urine
• Isosthenuric urine

  SG of 1.010 (the SG of the plasma ultrafiltrate)
• hyposthenuric urine

  SG lower than 1.010
• hypersthenuric urine


  SG higher than 1.010
• pKa change of polyelectrolytes

  Principle of reagent strip
• Odor: aromatic


  normal
• Foul, ammonia-like,pungent

  Bacterial decomposition, UTI
• Sweet/ fruity

  Ketone (diabetes, starvation, vomiting)
• Maple syrup


  Msud
• Mousy, musty odor

  Phenyketonuria
• Rancid odor


  Tyrosinemia
• Sweaty feet

  Isovaleric acidemia
• Cabbage odor

  Methionine malabsorption
• bleach odor urine

  contamination
• Rotting fish odor of urine

  Trimethyaminuria
• Sulfur odor urine


  Cystine Disorder
• Glucose and Bilirubin


  Reagent strip technique time : 30 seconds
• Ketones

  Reagent strip technique time : 40 seconds
• Specific gravity

  Reagent strip technique time : 45 seconds
• Protein

  pH

  Blood

  Urobilinogen

  Nitrite


  Reagent strip technique time : 60 seconds
• leukocyte esterase


  Reagent strip technique time : 120 seconds
• Multistix and Chemstrip.


  2 major types of reagent strips
• Procedure of urine reagent strip

  1. Dip strip briefly into well-mixed specimen at room

  temperature.

  2. Remove excess urine by touching edge of strip to

  container as strip is withdrawn.

  3. Blot the edge of the strip on a disposable absorbent

  pad.

  4. Wait the specified amount of time for the reaction to

  occur.

  5. Compare the color reaction of the strip pads to the

  manufacturer's color chart in good lighting.
• Errors caused by Improper technique:

  1. Unmixed specimen

  2. Allowing the strip to remain in the urine for an extended

  period → leaching of reagents from the pads

  3. Excess urine on the strip → distortion of the colors

  4. The amount of time for reactions to occur is specified by

  the manufacturer

  5. Light source accurate interpretation of color reactions

  6. Strip must be held close to the color chart w/o actually

  being placed on the chart.

  7. Specimen should be return to room temp before testing.
• QC for urine reagent strip

  1. Test open bottles of reagent strips with known positive

  and negative controls every 24 hours.

  2. Resolve control results that are out of range by further

  testing.

  3. Test reagents used in backup tests with positive and

  negative controls.

  4. Perform positive and negative controls on new reagents

  and newly opened bottles of reagent strips.

  5. Record all control results and reagent lot numbers.
• 4.5 to 8.0 pH


  Random urine pH
• 5.0 to 6.0 pH


  1st morning urine pH
• > 8.5 pH indicates

  Unpreserved urine
• Double indicator system


  Principle of REAGENT STRIP REACTIONS - pH
• Red to yellow


  color of pH 4-6
• Yellow to blue


  Color of pH 6-9