AUBF

• Reagent strips


  The primary method used for the chemical examination of urine
• Although easily used, reagent strips represent multiple complex, state-of-the-art chemical reactions
• Confirmatory methods are performed when available and necessary
• Nonreagent strip testing procedures

  Using tablets and liquid chemicals
• Reagent strips


  Chemical-impregnated absorbent pads attached to a plastic strip
• Color-producing chemical reaction


  Occurs when the absorbent pad comes in contact with urine
• Color intensities


  Compared on the manufacturers chart or read by an automated machine
• Semiquantitative value


  trace, 1+, 2+, 3+, 4+
• 2 major types of reagent strips

  • Multistix (Siemens)
  • Chemstrip (Roche)
• Reagent strips used is a matter of laboratory preference
• Reagent strips are also specified by instrumentation manufacturers
• 10 Parameters strip


  • pH
  • Protein
  • Glucose
  • Ketones
  • Blood
  • Bilirubin
  • Urobilinogen
  • Nitrite
  • Leukocytes
  • Specific gravity
• 4 parameters strip


  • Specific gravity
  • pH
  • Glucose
  • Protein
• Other parameters


  • Ascorbic acid
  • Creatinine
• Storage of Reagent Strips

  • Packaged in opaque containers with a desiccant to protect them from light, heat, volatile chemicals, and moisture
  • Stored at room temperature below 30°C
  • Check for discoloration with each use
  • Stamped with an expiration date
  • Keep container tightly stoppered
  • Check manufacturer's directions with each new lot number for changes in procedure
• Reagent Strip Technique


  1. Dip the reagent strip briefly into a well-mixed uncentrifuged urine specimen at room temperature

  2. Remove excess urine by touching the edge of the strip to the container as the strip is withdrawn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
• Quality Control


  • Test open bottle of reagent strips with known positive and negative controls
  • Resolve control results that are out of range by further testing
  • Test reagents used in backup tests with positive and negative controls
  • Record all control results and reagent lot numbers
• Controls


  • Several companies manufacture both positive and negative controls
  • Distilled water is not recommended as a negative control
  • All readings of the negative control must be negative
  • Positive control readings must agree with the published value by ± one color block
• Urine pH


  • The kidneys and lungs normally work in concert to maintain acid-base equilibrium
  • The lung excretes carbon dioxide
  • The kidneys secrete hydrogen in the form of ammonium ion, hydrogen phosphate and weak organic acids, and reabsorb bicarbonate
  • No normal values assigned to urine pH
  • In healthy individuals, urine pH may vary from 4.6–8
  • 1st morning: usually Acidic, 5-6
  • Following meals: Alkaline
  • pH of 9.0: improperly preserved specimen
• Causes of Acidic Urine


  • Diet high in protein and meat
  • Some fruits, such as cranberries
  • Patient with metabolic or respiratory acidosis
  • Therapeutic acidification to treat phosphate & calcium carbonate stones, UTI
• Causes of Alkaline Urine


  • Diet high in fruits and vegetables
  • Patient with metabolic or respiratory alkalosis
  • "alkaline-tide" following a meal
  • Induction of alkaline urine with sodium bicarbonate, potassium citrate, and acetazolamide to treat UA, CaOx or cystine stones, some UTI's, sulfonamide therapy, salicylate poisoning
• Summary of pH Reagent Strip

  • Double-indicator system with methyl red and bromthymol blue
  • Reaction range 5 to 9
  • No known interfering substances
  • Sources of error include nitrite, leukocytes, microscopic
• Urinary Protein


  • Most indicative of renal disease
  • Normal urine protein is less than 10 mg/dL or 100 mg/24 hours
  • Clinical proteinuria is ≥ 30 mg/dL
  • Albumin is the major protein (1/3) found in normal urine, along with Tamm-Horsfall protein and proteins from prostatic, seminal and vaginal secretions
• Causes of Proteinuria


  • Prerenal (Hemoglobinuria, Myoglobinuria, APR's, Bence Jones proteinuria)
  • Renal (Glomerular proteinuria, Tubular proteinuria, Orthostatic proteinuria, Microalbuminuria)
  • Postrenal (Lower urinary tract infections)
• Bence Jones Protein


  • Found in the urine of persons with multiple myeloma
  • Solubility characteristic: coagulates at 40°C-60°C, dissolves at 100°C
  • Confirmatory tests: serum electrophoresis or immunoelectrophoresis
• Causes of Glomerular Proteinuria


  • Abnormal substances (Amyloid material, Toxic substances, Immune complexes)
  • Increased pressure from the blood entering the glomerulus (Hypertension)
  • Strenuous exercise
  • Dehydration
  • Pre-ecclamptic state
• Causes of Tubular Proteinuria

  • Exposure to toxic substances and heavy metals
  • Severe viral infections
  • Fanconi's syndrome
• Orthostatic Proteinuria


  • Persistent benign renal proteinuria frequently in young adults
  • Increased urine protein only when an individual is in an upright position
  • Proteinuria disappears when a horizontal position is assumed
  • Caused by increased pressure on the renal vein
• Microalbuminuria


  • Presence of albumin in urine above the normal level but below the detectable range of conventional urine dipstick method
  • Enables patients to begin treatment before kidney disease occurs
  • Significant: 30-300 mg albumin/24 hours or 20-200 ug/min
• Postrenal Proteinuria


  • Protein is added to the urine as it passes through the lower urinary tract
  • Could be caused by presence of blood, prostatic fluid, spermatozoa, or bacterial/fungal infection
• Summary of Protein Reagent Strip

  • Principle is based on protein error of indicators
  • Multistix uses tetrabromphenol blue, Chemstrip uses 3',3",5',5"-tetrachlorophenol 3,4,5,6 tetrabromosulfopthalein
  • Sensitivity is 15-30 mg/dL albumin for Multistix, 6 mg/dL albumin for Chemstrip
  • Interference includes blood, nitrite, leukocytes, microscopic
• Acid Precipitation Technique for Protein


  Sulfosalicylic Acid Precipitation Test reacts equally with all forms of protein
• Albumin: Creatinine Ratio


  • Provides an estimation of the 24-hr microalbumin excretion
  • An albumin: creatinine ratio of 20-30 mg/g is indicative of albuminuria
  • Abnormal results are 30 to 300 mg/g
  • Reagent strip reactions utilize the dye bis (3',3", diodo-4',4"-dihydroxy-5,5"-dinitrophenyl)-3,4,5,6-tetra-bromo-sulphonphthalein (DIDNTB) for albumin, and the pseudoperoxidase activity of copper-creatinine complex for creatinine
• Urine Glucose


  • Most frequent chemical analysis performed on urine
  • Its value is in the detection and monitoring of diabetes mellitus
  • Glycosuria often occur in patients with hyperglycemia, including diabetes mellitus, gestational diabetes, and hyperglycemia of nondiabetic origin
• Classification of Diabetes Mellitus

  • Type 1 diabetes (previously IDDM or juvenile-onset)
  • Type 2 diabetes (previously NIDDM or adult-onset)
  • Other specific types
  • Gestational diabetes
• Clinical Significance of Urine Glucose

  • Almost all glucose reabsorbed in PCT
  • Renal threshold for glucose is 160-180 mg/dL
  • Glycosuria often occur in patients with hyperglycemia, including diabetes mellitus, gestational diabetes, and hyperglycemia of nondiabetic origin (pancreatitis, acromegaly, Cushing syndrome, hyperthyroidism, pheochromocytoma, thyrotoxicosis)
• IDDM or juvenile-onset diabetes


  Diabetes characterized primarily by an absolute deficiency of insulin
• NIDDM or adult-onset diabetes

  Diabetes characterized primarily by insulin resistance (that is, insulin ineffective in target tissue) and insulin secretory defect
• Other specific types of diabetes

  • Specific genetic defects
  • Surgery
  • Drugs
  • Other things, have caused hyperglycemia
• Gestational DM (GDM)


  Diabetes that develops during pregnancy