Lactate Dehydrogenase (LDH) Enzyme Quiz

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What is the enzyme used in the KARMEN METHOD for the assay of AST levels?

Alkaline phosphatase

Malate dehydrogenase (MD) (correct)

Lactate dehydrogenase (LDH)

Alanine aminotransferase (ALT)

How long is AST activity stable in plasma under refrigerated conditions?

3-4 days (correct)

1-2 days

7-8 days

5-6 days

Which condition may falsely increase plasma AST concentration?

Hyperthyroidism

Dehydration

Blood clotting

Hemolysis (correct)

What effect might heavy metals have on AST levels?

Decrease AST levels (D) Signup and view all the answers

Which medical condition is associated with hepatic congestion and liver damage leading to release of AST into the bloodstream?

Congestive heart failure (B) Signup and view all the answers

In what time frame does AST release into the bloodstream typically peak after a myocardial infarction?

24-36 hours (A) Signup and view all the answers

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 (C) Signup and view all the answers

What is the primary function of the LDH-6 isoenzyme?

Responsible for the metabolism of methanol and ethylene glycol (D) Signup and view all the answers

What is the optimal pH range for the forward (Wacker) reaction of the LDH assay?

pH 8.3 to 8.9 (B) Signup and view all the answers

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 (D) Signup and view all the answers

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 (D) Signup and view all the answers

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 (C) Signup and view all the answers

What is the primary function of the lactate dehydrogenase (LDH) enzyme?

To catalyze the interconversion of lactic and pyruvic acids via hydrogen transfer (A) Signup and view all the answers

Which of the following isoenzymes of LDH is most abundant in skeletal muscle?

LD-4 (A) Signup and view all the answers

Which of the following conditions is NOT associated with an increase in LDH levels?

Hypoglycemia (D) Signup and view all the answers

Which of the following statements about LDH isoenzymes is correct?

LD-3 is composed of two 'H' subunits and two 'M' subunits (HHMM) (B) Signup and view all the answers

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 (B) Signup and view all the answers

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 (D) Signup and view all the answers