Lecture 2/16

Cards (24)

  • Leukocytes
    • indication of UTI
    • enzymatic reagent pad reaction
    • esterases present in granulocytes - looking for segmented neutrophils
  • Macroscopic analysis
    • blood
    • potentially significant in any quantity
    • reagent pad detects 3 types
    • RBC (hematuria) - intact RBCs
    • hemoglobin - free; occurs when red blood cells hemolyze; aka hemoglobinuria
    • myoglobin - oxygen carrying pigment found in muscle
  • positive blood dipstick is not specific to specific type
    trace amounts of blood may not change color of dipstick
  • Macroscopic analysis
    • hematuria
    • pathological: renal calculi (kidney stones), glomerulonephritis, pyelonephritis, tumors, trauma, exposure to toxic chemicals/drugs
  • nonpathological causes of hematuria - strenuous exercise, menstrual contamination
  • pH indications of hematuria
    • alkaline pH will lyse intact RBCs
    • delay in testing can lyse RBCs as pH increases
  • upon microscopic examination of alkaline urine, will not see intact RBCs or see ghost red cells (membrane very faint; Hgb leaked out of RBC and RBC filled with water or urine)
  • Macroscopic analysis - blood
    • hemoglobinuria - lysis of red cells in urinary tract or in alkaline urine
  • if hemoglobin pad is negative, myoglobin will be negative
    • therefore, if you receive myoglobin urine test, first do blood dipstick and if negative, do no further testing
  • methods of testing for blood - electrophoresis, adsorption spectrophotometry, immunodiffusion, and radioimmunoassays (historically)
  • macroscopic analysis - blood
    • reagent pad reaction uses pseudoperoxidase activity of Hgb
  • In reagent pad reaction for blood, sample provides peroxidase, while in glucose, reagent has peroxidase
  • Reaction interference of blood reagent pad
    • false positives with vegetable peroxidases - some vegetables have increased peroxidase
  • biliary obstruction can mean duct from gallbladder to liver or or liver to small intestine is blocked
  • macroscopic analysis - bilirubin
    • properties
    • normally negative
    • bilirubin in urine will always be conjugated
    • breaks down in light
  • macroscopic analysis - urobilinogen
    • source - degradation of hemoglobin; 1 mg/dL is normal; varies; levels rise 2-3 hours after a meal
  • chemstrip for urobilinogen - has different chemical
    positive is pink to red
  • macroscopic analysis - nitrite
    • background - normal diet with green vegetables results in nitrate in the urine; some bacteria reduce nitrate to nitrite (NO2); other bacteria reduce all the way to nitrogen (N2)
  • macroscopic analysis - nitrites
    • clinical significance - detects UTI's; positive indicates cystitis and pyelonephritis; evaluates effectiveness of antibiotic therapy
  • interferences of nitrite
    • false positive from pigmented urines
    • false negatives from bacteria that don't reduce nitrate, or reduce all the way to nitrogen
    • bacteria present, but will not be positive
    • false negative if diet is deficient from. nitrate rich foods
    • not enough nitrate to become nitrite
    • diluted specimens will give false negative
    • not enough contact time in bladder to convert nitrate to nitrite
  • Observances and Determinations -will not trigger microscopic
    • glucose - sometimes yes for microscopic evaluation to check if there is yeast infection especially in diabetics
  • microscopic analysis
    • can help differentiate UTI from renal disease
    • usually done on unstained "wet prep" - special chamber
  • having a special chamber for urine sediment analysis standardized amount of sediment examined
  • glitter cells result from brownian motion; before lysing, granules move around and WBC's appear to glitter