Biochemical Testing Flashcards
Which method only measures the number of particles in solution?
Osmolality
What process is solely responsible to water reabsorption throughout the entire nephron?
passive transport
How should you store reagent strips?
avoid exposure to moisture, chemicals, heat, and light, store at room temp below (30*C), keep desiccant packet inside bottle, and close vial immediately after use
When should QC be performed on the reagent strips?
use both pos and neg controls a minimum of once every 24 hours, when a new bottle of strips is opened, and when a new lot is received
What is the normal for Specific Gravity?
1.003 to 1.030
Urine with a specific gravity of 1.010
Isosthenuria
Urine with a specific gravity of < 1.010
Hyposthenuric
What is the most common cause of Hyposthenuria?
diabetes insipidus or renal disease
Urine with a specific gravity >1.010
Hypersthenuric
Limitation of specific gravity
only determines specific gravity from 1.000-1.030 in 0.005 increments
What lowers specific gravity readings?
highly buffered alkaline urine
How do you correct for alkaline urine?
when pH is > 7 add 0.005 to the strip reading if it is being read manually
Principle of pH
Double indicator of Methyl Red and Bromthymol Blue
Reference range for pH
There isn’t a reference range for urine pH because broad variances occur daily in normal patients
When is acidic urine common during the day?
acidic urine is common in the morning (5-6)
WHen is urine suspicious of tampering as far as pH?
below 5 is suspicious
Meats and high protein diet lead to what pH in the urine?
acidic urine
Vegetarian diet leads to what type of pH in urine
alkaline urine
What is it called when you have basic urine after a large meal?
Alkaline Tide
What leads to ACIDIC blood and ALKALINE urine?
Renal tubular acidosis
what cells contain leukocyte esterase?
granulocytic white blood cells (neuts, eos, basos, and monos)
Not found in RBCs, Lymphocytes, and epithelial cells
Leukocyte Esterase Principle
Indoxylcarbonic acid ester > leukocyte esterase > indoxyl
indoxyl + diazonium salt >purple azodye
Leukocyte Esterase is associated with what infections?
Bacterial infections or Trichomonas infections
In bacterial infections with a positive leukocyte esterase, what result usually accompanies it?
a positive nitrite reaction
Positive leukocyte esterase may be found without bacteriuria in what 4 conditions?
- Trichomonas
- Chlamydia
- Yeast infections
- inflammation of renal tissues
What is the specificity of Leukocyte Esterase?
specific for esterase
What causes false positive for Leukocyte esterase?
- Vaginal Contamination
2. Medications that falsely color urine
What causes false negatives for Leukocyte esterase?
- increased glucose >3 g/dl
- increased protein > 500mg/dL
- High specific gravity
- Certain medications
Nitrites:
- principle
Greiss Reaction
Nitrites:
- clinical significance
Bacteria convert nitrates into nitrites. Nitrites are an abnormal finding
Nitrites:
- Indicates the presence of what?
Gram Negative bacteria
Nitrite:
- What is it when bacterial infection ascends from the bladder to the ureters and kidneys?
Pyelonephritis
Nitrite:
- False Positives
- Falsely colored urine
2. Improper storage allowing for bacterial proliferation
Nitrite:
- False Negatives
- Ascorbic Acid (vitamin C)
2. The enzyme is only found in gram neg bacteria
