AUBF: Chemical Examination

• Reagent strip - Interpreted by comparing the color produced on the pad with a chart supplied by the manufacturer.
• Care of Reagent Strips: Store below 30C
• Quality Control of Reagent Strips: Test open bottles of reagent strips with known positive and negative controls every 24 hr.
• Major regulator of acid-base content of the body: Lungs and kidney
• Reabsorbed in CT - Bicarbonate
• First morning Urine (healthy individuals) - pH 5.0-6.0
• Normal Random sample - pH 4.5 – 8.0
• Principle of pH (Reagent Strip Reaction): DOUBLE-INDICATOR SYSTEM OF METHYL RED ANDBROMTHYMOL BLUE.
• pH (Reagent Strip Reaction): Measures pH between 5 – 9
• pH (Reagent Strip Reaction):

  • Methyl red to red to yellow (pH range 4-6)
  • Bromthymol blue to yellow to blue (pH range 6-9)
  • pH 5 = orange ; pH 9 = green
• Protein is the most indicative of renal disease.
• Proteinuria = early renal dse
• Protein normal value: <10mg/dL or 100mg/24h
• Clinical proteinuria ≥ 30mg/dL or 300 mg/L

  ◦ Pre-renal ◦ Post-Renal

  ◦ Renal
• Protein (Pre-renal Proteinuria) is caused by conditions affecting the plasma prior to reaching the kidney. It is not indicative of actual renal disease
• Protein (Pre-renal Proteinuria) Frequently transient: Hemoglobin, Myoglobin, APR due to inflammation, and not usually discovered in routine urinalysis
• Bence Jones Protein - Seen in case of multiple myeloma. Monoclonal immunoglobulin light chains
• Bence Jones Protein Screening test: Solubility test

  ◦ Coagulates at 40-60°C (turbid)◦ dissolves when tempt reaches 100°C (clear)

  ◦ Filter at 100°C and observe for turbidity as it cools to 40-60°C
• Bence Jones Protein Confirmatory : serum electrophoresis
• Protein (Renal Proteinuria) is a true renal disease (glomerular/tubular dse)
• Protein (Renal Proteinuria) - Increased CHON, RBCs, WBCs
• Protein (Renal Proteinuria) Causes: amyloid material, toxic substances, and the immune complexes found in lupus erythematosus and streptococcal glomerulonephritis
• Protein (Renal Proteinuria): Strenuous exercise, dehydration or associated with hypertension pre- eclampsia
• TUBULAR PROTEINURIA - disorders affecting tubular reabsorption and filtered albumin can no longer be reabsorbed
• TUBULAR PROTEINURIA - Causes: exposure to toxic substances and heavy metals, severe viral infections, Fanconi syndrome.
• Protein (Renal Proteinuria): Benign Proteinuria: Transient
• ORTHOSTATIC (POSTURAL) PROTEINURIA - seen frequently in young adult. It appears in vertical position; disappears in horizontal position
• MICROALBUMINURIA - (not detected in routine test) is a diabetic nephropathy leading to reduced glomerular filtration and eventual renal failure. Prevented through better stabilization of blood glucose levels and controlling of hypertension.
• Albumin: creatine ratio > 3.4mg/mmol
• Protein can be added to a urine specimen as it passes through the structures of the lower urinary tract (ureters, bladder, urethra, prostate, and vagina)
• Protein (Post-renal Proteinuria): presence of prostatic fluid and large amounts of spermatozoa.
• Protein (Post-renal Proteinuria): the presence of blood as the result of injury or menstrual contamination
• Principle of Protein (Reagent Strip) - Protein error of indicators
• Protein (reagent Strip) - Reagent:◦ Multistix: Tetrabromphenol blue
• Protein (Reagent Strip)

  Sensitivity:

  ◦ Multistix: 15–30 mg/dL albumin

  ◦ Chemstrip: 6 mg/dL albumin
• Other Albumin Qualitative test general principle: Precipitation of protein by heat and coagulation by chemical reagents
• Other Albumin Qualitative test:

  Heat and Acetic Acid

  ◦ Reagent: Acetic Acid◦ (+) Result: White Cloudiness
• Sulfosalycilic Acid (SSA)/ Exton’s Test

  ◦ Reagent: Sulfosalicylic Acid or Sodium Sulfate

  ◦ (+) Result: White ring at zone of contact
• Heller’s Ring Test

  ◦ Reagent: Concentrated nitric acid

  ◦ (+) Result: White opaque ring
• Purdy’s Test

  ◦ Reagent: 50% Acetic Acid◦ (+) Result: White cloudiness