Chemical Examination Flashcards
Testing of a urine specimen should be done as soon as possible (within ___ hours) after collection.
2 hours
Principle of pH
Double Indicator System
Reading time of pH
Immediate (60 seconds)
Indicator of pH
Methyl Red
Bromthymol Blue
Correlation of pH: (3)
Nitrite
Leukocyte Esterase
Microscopic
Clinical Significance of Urine pH (6)
- Respiratory or metabolic acidosis/ketosis
- Respiratory or metabolic alkalosis
- Defects in renal tubular secretion and reabsorption of acids and bases
- Treatment of UTIs
- Precipitation/ identification of crystals
- Determination of unsatisfactory specimens
The most common chemical abnormalities detected in urine are increased amounts of: (7)
- sugars (e.g., glucose, galactose)
- protein
- RBCs
- WBCs
- bilirubin
- ketones
- urobilinogen
a diet high in vegetables and fruits makes the urine pH more?
Alkaline
Normal pH range
4.6 - 8
High protein intake results in _________ urine
Alkaline
Principle of Protein
Protein Error of Indicator
Normal protein concentration excreted into the urine
10 mg/dL or 100 mg/24hours
This protein makes up 1/3 of the total protein excreted into the urine
Albumin
If 1/3 of proteins in urine is albumin, what are the remainder of these proteins?
Small globulins with molecular weight of < 50,000
This buffer is incorporated in protein reagent strip
Citrate buffer
pH and indicator of protein
pH - 3
Indicator - Tetrabromphenol blue
Color of indicator at pH 3
Yellow
Trace value of protein
30 mg/dL
Three major categories of causes of Proteinuria:
Pre-renal
Renal
Post- renal
Major category of causes of proteinuria:
- caused by conditions affecting the plasma prior to reaching the kidney
-not indicative of actual renal disease
Pre-renal protenuria
Major category of causes of proteinuria:
- associated with true renal disease
- maybe the result of either glomerular or tubular damage
Renal Proteinuria
caused by the addition of protein to the urine as it passes through the structure of the lower urinary tract
Post-renal protenuria
Reaction interference in Protein
Cause of false positive protein: (6)
- highly buffered interference alkaline urine
- pigmented specimens,
- detergents
- antiseptics
- loss of buffer from prolonged exposure of the strip to the specimen reagent
- high specific gravity
Correlations of Protein: (4)
- Blood
- Nitrite
- Leukocytes
- Microscopic
Reaction interference in Protein
Cause of false negative protein: (2)
- Proteins other than albumin
- Microalbuminuria
Principle of Glucose
Double Sequential Enzymatic Reaction (Glucose Oxidase)
Glucose is usually detected in urine. It is excreted into the urine when the plasma level reaches renal threshold of 160 - 180 mg/dL.
A. First statement is true, second statement is true.
B. First statement is correct, second statement is incorrect.
C. First statement is incorrect, second statement is correct.
D. First statement is false, second statement is false.
C. First statement is incorrect, second statement is correct.
Glucose is not usually detectable in urine.
Enumerate the disease associated with Hyperglycemia-associated glycosuria: (8)
- Diabetes mellitus
- Pancreatitis
- Pancreatic cancer
- Cushing syndrome
- Hyperthyroidism
- CNS damage
- Stress
- Gestational diabetes
Enumerate the disease associated with Renal-associated glycosuria: (8)
- Fanconi syndrome
- Advanced renal disease,
- Pregnancy
- Osteomalacia
Reaction interference in Glucose reagent strip that occurs due to contamination by oxidizing agents and detergents
False-positive
Reaction interference in Glucose reagent strip that occurs due to high levels of ascorbic acid, high levels of ketones, high specific gravity, low temperature, improperly preserved specimens
False negative
Correlation of Glucose: (2)
- Ketones
- Protein
This is the product of incomplete fat metabolism
Ketones
Presence of ketones in urine indicates what?
Acidosis
Three ketone bodies present in urine:
Acetoacetic (diacetic) acid
Acetone
3-hydroxybutyrate.
Principle of Ketones
Sodium Nitroprusside reaction