P1.3-LIVER LAB-ER BOI Flashcards
It is the basis of commonly used methods today to measure bilirubin by reacting bilirubin with diazotized sulfanilic acid to produce a colored product.
classic diazo reaction
What did Van Den Bergh discover about the diazo reaction
It may be applied to serum samples only in the presence of an accelerator, as conjugated bilirubin does not need a solubilizer, while unconjugated bilirubin does.
The first clinically useful methodology for the quantitation of bilirubin in serum samples using 50% methanol as an accelerator
Evelyn and Malloy method
The most commonly used method for bilirubin measurement, which is more sensitive than the Evelyn and Malloy method and uses caffeine sodium benzoate as an accelerator.
Jendrassik and Grof method
A point-of-care test for measuring bilirubin in the neonatal population using reflected light from the skin.
bilirubinometry
How are unconjugated and conjugated bilirubin identified using diazo methods?
Unconjugated bilirubin reacts with diazotized sulfanilic acid only in the presence of an accelerator, while conjugated bilirubin reacts directly
Conjugated bilirubin that is bound to albumin, often seen in hepatic obstruction.
delta bilirubin
What are the three fractions of total bilirubin?
Unconjugated bilirubin, conjugated bilirubin, and delta bilirubin
What are the proper terms for bilirubin classification?
Unconjugated and conjugated bilirubin, as indirect and direct bilirubin are outdated terms.
What sample type is preferred for the Evelyn and Malloy method
Serum
Why should fasting samples be used for bilirubin testing?
Lipemia can falsely elevate bilirubin concentrations.
Why should hemolyzed samples be avoided in bilirubin testing?
They can decrease the reaction of bilirubin with diazotized sulfanilic acid, resulting in falsely decreased bilirubin concentration.
How should bilirubin specimens be handled?
They must be protected from light to prevent a reduction in bilirubin values by 30% to 50% per hour.
How stable are bilirubin samples?
Stable for 2 days at room temperature, 1 week at 4 degrees Celsius, and indefinitely at minus 20 degrees Celsius.
What causes increased levels of urinary urobilinogen?
Hemolytic disease and defective liver cell function, such as hepatitis
What does the absence of urobilinogen in urine and stool indicate
Complete biliary obstruction
How is urinary urobilinogen determined?
Urobilinogen reacts with para-dimethylaminobenzaldehyde (Ehrlich’s reagent) to form a red color measured spectrophotometrically.
What is the reference range for urinary urobilinogen?
0.1 to 1.0 Ehrlich unit every 2 hours; 0.5 to 4.0 Ehrlich units per day.
How is fecal urobilinogen measured
Using a semiquantitative method with aqueous extract of fresh feces and Ehrlich’s reagent.
What is the reference range for fecal urobilinogen?
75 to 275 Ehrlich units per 100 grams of fresh feces;
75 to 400 Ehrlich units per 24 hours.
What are the primary liver enzymes used in liver function tests?
Alanine aminotransferase,
aspartate aminotransferase,
alkaline phosphatase, 5’-nucleotidase,
gamma-glutamyl transferase, and
lactate dehydrogenase.
What do elevated aminotransferases indicate?
Hepatocellular damage to the liver
What conditions cause the highest levels of aspartate aminotransferase and alanine aminotransferase?
Acute conditions such as
viral hepatitis,
drug- and toxin-induced liver necrosis, and
hepatic ischemia.
What non-liver conditions can also elevate aminotransferases?
Acute myocardial infarction,
renal infarction, and
progressive muscular dystrophy.
