18 Questions
What is the enzyme used in the KARMEN METHOD for the assay of AST levels?
Malate dehydrogenase (MD)
How long is AST activity stable in plasma under refrigerated conditions?
3-4 days
Which condition may falsely increase plasma AST concentration?
Hemolysis
What effect might heavy metals have on AST levels?
Decrease AST levels
Which medical condition is associated with hepatic congestion and liver damage leading to release of AST into the bloodstream?
Congestive heart failure
In what time frame does AST release into the bloodstream typically peak after a myocardial infarction?
24-36 hours
What is the diagnostic significance of the 'flipped pattern' of LDH isoenzymes in the diagnosis of myocardial infarction?
Indicates an increase in LD-1 relative to LD-2, which is characteristic of myocardial infarction
What is the primary function of the LDH-6 isoenzyme?
Responsible for the metabolism of methanol and ethylene glycol
What is the optimal pH range for the forward (Wacker) reaction of the LDH assay?
pH 8.3 to 8.9
Which of the following is a disadvantage of the Wroblewski-Ladue (reverse/indirect) method for measuring LDH activity?
It is influenced by LDH inhibitors and early loss of linearity
Which of the following statements about the tissue distribution of LDH isoenzymes is correct?
LD-1 and LD-2 are present to approximately the same extent in the heart tissue
What is the diagnostic significance of the detection of LDH isoenzymes in spermatozoa and semen?
Indicates the presence of seminoma, a type of testicular cancer
What is the primary function of the lactate dehydrogenase (LDH) enzyme?
To catalyze the interconversion of lactic and pyruvic acids via hydrogen transfer
Which of the following isoenzymes of LDH is most abundant in skeletal muscle?
LD-4
Which of the following conditions is NOT associated with an increase in LDH levels?
Hypoglycemia
Which of the following statements about LDH isoenzymes is correct?
LD-3 is composed of two 'H' subunits and two 'M' subunits (HHMM)
Which of the following is an important serological marker for the diagnosis, staging, recurrence, and monitoring of germ cell tumors?
LDH coupled with alpha-fetoprotein and human chorionic gonadotropin
Which of the following diagnostic methods is considered more sensitive and cost-effective than the analysis of LDH isoenzymes for the diagnosis of myocardial infarction (MI)?
Cardiac troponin I assay
Test your knowledge on Lactate Dehydrogenase (LDH) enzyme, its reference range, tissue sources, and diagnostic significance of its increase in various diseases. Learn about the different isoenzymes and their distribution in the body.
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