LAB questions Flashcards
what is the reference range of ALP
40-140 U/L
How is ALP classified in enzyme nomenclature
ALP is classified as a Hydrolase
how is an international unit defined
the amount of enzyme that will catalyze the reaction of 1 micromol of substrate per minute per liter of serum
What is the clinical significance of an increased ALP
Increased ALP is seen in extrahepatic & intrahepatic obstructions, bone diseases & 3rd trimester of pregnancy
what are isoenzymes
isoenzymes are different forms of an enzyme; differ in amino acid sequence but catalyze the same reaction
what are the four main isoenzymes of ALP in their order of electrophoretic separation
Liver, Bone/placenta, Intestine
what is the difference between endpoint & kinetic measurements
endpoint is read at fixed times kinetic is multiple continuous readings taken every 30-60 seconds
Which type of assay is preferable for enzyme assays
kinetic assay is preferred because it is more accurate
what is the reference range of total bilirubin
3-17 micromol/ L
what is the principle of Jendrasik Grof reaction
bilirubin + diazo reagent —> Azobilirubin + Alakali = blue
2 measurements are made on each sample ; conjuagted bulirubin (w/o accelerator) & total bilirubin ( w/ accelerator)
after a period of time of time Ascorbic acid is added to destroy excess diazo regent & stop reaction
Alkaline tartrate is added to make the pH alkaline ( to get blue color) & measured at 600nm
how will hemolysis affect bilirubin
hemolysis will alter bilirubin concentration & give falsely low results
what is the purpose of an accelerator in bilirubin methods
allows for unconjugated bilirubin to be made soluble so it can react with the diazo reagent & be measured
what accelerator is used in the Jendrassik-Grof method
Caffeine sodium benzoate
why are many babies jaundice in the first 5 days after birth. what is the normal pattern ?
before birth unconjuagted bilirubin is cleared by the placenta
the enzyme UDP-glucuronyl transferase is needed to conjugate bilirubin. which is one of the last enzymes to develop in newborns, resulting in increased unconjugated bilirubin in the first few weeks of life
4 scenarios where neonatal jaundice is abnormal
- appears in first 24 hrs after birth
- may indicate increased RBC breakdown - > 204 micromol/L in full term infants
340 micromol/L in premature infants - stays elevated after first week in full term babies
- there is an increase in conjugated bilirubin
- indicates it is not an enzyme problem
