GGT AND LDH

a

What inorganic component is present in lactate dehydrogenase (LDH)?

A. Zinc

B. Iron

C. Copper

D. Magnesium

E. Calcium

a

Which enzyme form composed of four C subunits is found in spermatozoa and semen but has never been detected in serum?

A. LD-X

B. LD4

C. LD5

D. LD6

E. HBD

a

Which isoenzyme of LDH is considered the most negatively charged?

A. LD1

B. LD2

C. LD3

D. LD4

E. LD5

a

What is the reference range for total Lactate Dehydrogenase (LDH)?

A. 125–220 U/L

B. 6–55 U/L

C. 5–38 U/L

D. 300–500 U/L

E. 50–100 U/L

a

In the electrophoretic mobility pattern of LDH, which isoenzyme migrates fastest toward the anode (first position listed in standard electrophoresis output)?

A. LD1

B. LD2

C. LD3

D. LD4

E. LD5

a

What degree of elevation in LDH levels (expressed as times normal) is associated with conditions like hepatitis and systemic shock?

A. Pronounced elevation (5 or more times normal)

B. Slight elevation (up to 3 times normal)

C. Moderate elevation (3 to 5 times normal)

D. Mild elevation (1 to 2 times normal)

E. No elevation

a

Which method for LDH measurement utilizes the forward reaction converting lactate to pyruvate?

A. Wacker method

B. Wroblewski-La Due method

C. Rosalki-Wilkinson method

D. Cherry-Crandall method

E. Reitman-Frankel method

a

Which GGT diagnostic procedure substrate yields p-nitroaniline?

A. γ-glutamyl-p-nitroanilide

B. Ketobutyrate

C. Pyruvate

D. Phenazine methosulfate

E. p-nitrophenylhydrazine

a

Which enzyme is used to differentiate whether an elevated Alkaline Phosphatase (ALP) is due to a skeletal disorder/pregnancy or a hepatobiliary disorder?

A. GGT

B. LDH

C. HBD

D. AST

E. ALT

a

What is the wavelength range used to measure the absorbance of p-nitroaniline in GGT determination?

A. 405 nm to 420 nm

B. 340 nm

C. 440 nm to 525 nm

D. 280 nm

E. 600 nm to 650 nm

b

LDH catalyzes the reversible conversion of lactate and NAD into which products?

A. Ketobutyrate and NADH

B. Pyruvate and NADH

C. Glutathione and NADPH

D. Oxaloacetate and NADP

E. Alanine and NADH

b

What is the normal physiological order of LDH isoenzyme concentrations in human serum?

A. LD 1 > 2 > 3 > 4 > 5

B. LD 2 > 1 > 3 > 4 > 5

C. LD 5 > 4 > 3 > 2 > 1

D. LD 3 > 2 > 1 > 4 > 5

E. LD 1 > 3 > 2 > 4 > 5

b

What phenomenon regarding LDH isoenzymes is often associated with Acute Myocardial Infarction (AMI)?

A. LD2 > LD1

B. LD flip (LD1 > LD2)

C. LD5 > LD4

D. Total loss of LD3

E. Absence of LD1

b

What is the kinetic difference between the Wroblewski-La Due method and the forward reaction (Wacker method) for measuring LDH?

A. Wroblewski-La Due is 2x slower

B. Wroblewski-La Due is 3x faster

C. Wroblewski-La Due measures at 440 nm

D. Wroblewski-La Due is unaffected by pH

E. Wroblewski-La Due requires zinc as a co-substrate

b

What reaction is catalyzed by Alpha-hydroxybutyric dehydrogenase (HBD)?

A. Conversion of lactate to pyruvate

B. Conversion of ketobutyrate using NADH

C. Synthesis of glutathione

D. Breakdown of amino acids

E. Phosphorylation of glucose

b

Which of the following conditions causes the highest elevation of LDH?

A. Acute appendicitis

B. Megaloblastic anemia (Pernicious anemia)

C. Hypothyroidism

D. Nephrotic syndrome

E. Muscular dystrophy

b

How long after the onset of AMI do total LDH levels peak?

A. 12–24 hours

B. 48–72 hours

C. 10 days

D. 5–7 days

E. 2–4 hours

b

What temperature condition should be avoided when storing LDH specimens because of cold-labile isoenzymes?

A. Room temperature

B. Freezing temperature

C. 37°C

D. 25°C

E. Body temperature

b

What is the reference range of GGT for adult males at 37°C?

A. 5–38 U/L

B. 6–55 U/L

C. 125–220 U/L

D. 10–100 U/L

E. 1–10 U/L

b

GGT is involved in transferring the gamma-glutamyl group from gamma-glutamyl peptides to:

A. Glucose and lipids

B. Amino acids, H2O, and small peptides

C. Nucleic acids and ATP

D. Fatty acids and cholesterol

E. Lactate and pyruvate

c

Which LDH isoenzymes are known to be cold labile fractions?

A. LD1 and LD2

B. LD2 and LD3

C. LD4 and LD5

D. LD1 and LD5

E. LD3 and LD4

c

Which sub-unit tetramer structure represents LD1?

A. HHHM

B. HHMM

C. HHHH

D. HMMM

E. MMMM

c

Which tissue source is associated with LD3?

A. Heart and RBCs

B. Liver and skeletal muscle

C. Lung, lymphocytes, spleen, and pancreas

D. Spermatozoa

E. Brain and prostate

c

LD6 represents which enzyme?

A. Alpha-hydroxybutyric dehydrogenase

B. Gamma-glutamyl transferase

C. Alcohol dehydrogenase

D. Alkaline phosphatase

E. Creatine kinase

c

How long after the onset of AMI do LDH levels typically increase in the serum?

A. 1–2 hours

B. 4–8 hours

C. 12–24 hours

D. 48–72 hours

E. 10 days

c

Which method is used to measure Alpha-hydroxybutyric dehydrogenase (HBD)?

A. Wacker method

B. Wroblewski-La Due method

C. Rosalki-Wilkinson method

D. Cherry-Crandall method

E. Reitman-Frankel method

c

Which of the following conditions causes a moderate elevation (3 to 5 times normal) of LDH?

A. Megaloblastic anemia

B. Widespread carcinomatosis

C. Pulmonary infarction

D. Nephrotic syndrome

E. Hypothyroidism

c

What color product is formed in the colorimetric Wacker method using p-nitrophenylhydrazine?

A. Blue-purple

B. Bright yellow

C. Golden brown

D. Deep red

E. Colorless

c

Which anticoagulant/specimen factor should be avoided because it can inhibit LDH activity?

A. Heparin

B. Serum separator gel

C. Oxalate

D. Room temperature storage

E. Centrifugation

c

In contrast to LDH, how does hemolysis affect GGT measurement?

A. Hemolysis severely falsely elevates GGT

B. Hemolysis inhibits GGT activity completely

C. GGT is not affected by hemolysis

D. Hemolysis turns GGT blue-purple

E. Hemolysis causes GGT to precipitate

d

Which tissue is NOT a major source of Gamma-Glutamyl Transferase (GGT)?

A. Kidney

B. Brain

C. Pancreas

D. Skeletal muscle

E. Liver

d

Elevated levels of GGT are most characteristically observed in which type of condition?

A. Bone fracture

B. Pregnancy

C. Skeletal dystrophy

D. Hepatobiliary disorders

E. Hypothyroidism

d

Which drug is an enzyme inducer that can cause elevated GGT levels?

A. Penicillin

B. Aspirin

C. Paracetamol

D. Phenobarbital

E. Insulin

d

What is the reference range of GGT for adult females at 37°C?

A. 125–220 U/L

B. 6–55 U/L

C. 10–100 U/L

D. 5–38 U/L

E. 50–150 U/L

d

Which tetramer composition corresponds to LD5?

A. HHHH

B. HHHM

C. HHMM

D. MMMM

E. HMMM

d

Which elevation level of LDH (up to 3 times normal) is expected in hypothyroidism or nephrotic syndrome?

A. Pronounced elevation

B. Extreme elevation

C. Moderate elevation

D. Slight elevation

E. No change

d

​In the kinetic Wacker method (forward reaction), what change is measured at 340 nm?

A. Decrease in absorbance as NADH is converted to NAD

B. Increase in absorbance as pyruvate is converted to lactate

C. Decrease in absorbance as NAD is converted to NADH

D. Increase in absorbance as NAD is converted to NADH

E. No change in absorbance

d

How long after an AMI episode do LDH levels typically normalize?

A. 24 hours

B. 48 hours

C. 72 hours

D. Within 10 days

E. 30 days

d

What is the stability limit for GGT samples according to sources of error guidelines?

A. 24 hours

B. 3 days

C. 5 days

D. 1 week

E. 1 month

d

What reagents are used in the colorimetric Wacker method to produce a positive blue-purple color?

A. Ketobutyrate and NADH

B. p-nitrophenylhydrazine and sodium hydroxide

C. γ-glutamyl-p-nitroanilide and glycylglycine

D. Phenazine methosulfate and nitroblue tetrazolium

E. Oxalate and lactate

e

Which tissue is the primary origin of LD5?

A. Heart

B. Lung

C. Spleen

D. Erythrocytes

E. Skeletal muscle

e

In patients with arteriosclerotic failure or drug hepatotoxicity, which elevated band/isoenzyme may appear?

A. LD1

B. LD2

C. LD3

D. LD4

E. LD6

e

In the Wroblewski-La Due method, how is enzymatic activity measured at 340 nm?

A. Increase in absorbance as NAD is converted to NADH

B. Increase in absorbance as pyruvate is converted to lactate

C. Increase in absorbance of p-nitroaniline

D. Color change from blue to golden brown

E. Decrease in absorbance as NADH is converted to NAD

e

Why must hemolyzed specimens be rejected for LDH testing?

A. RBCs contain inhibitors of LDH

B. Hemolysis causes LDH to degrade instantly

C. Hemolysis causes sample turbidity only

D. RBCs consume all NAD in the tube

E. LDH is significantly more concentrated in RBCs than in plasma

e

Which condition listed below is classified under "Slight Elevation" of LDH?

A. Megaloblastic anemia

B. Systemic shock

C. Hepatitis

D. Myocardial infarction

E. Cholangitis

e

Chronic ingestion of which substance leads to GGT elevation as a marker of abuse/intake?

A. Glucose

B. Aspirin

C. Caffeine

D. Vitamin C

E. Alcohol

e

What is the expected GGT level in patients with skeletal disorders or during pregnancy?

A. Markedly elevated

B. Moderately elevated

C. Slightly elevated

D. Variable elevation

E. Normal

e

What preferred sample specimen is recommended for LDH analysis?

A. Whole blood with oxalate

B. EDTA Plasma

C. Heparinized Plasma

D. Fluoride Plasma

E. Serum

e

Which disorder exhibits a moderate elevation (3 to 5 times normal) of LDH?

A. Infectious mononucleosis

B. Hepatitis

C. Renal infarction

D. Hypothyroidism

E. Infectious mononucleosis (and Muscular dystrophy)

e

Which enzyme transfers gamma-glutamyl groups and plays a key role in regulating tissue glutathione levels and amino acid transport across cell membranes?

A. Lactate Dehydrogenase

B. Alpha-hydroxybutyric dehydrogenase

C. Alcohol dehydrogenase

D. Alkaline phosphatase

E. Gamma-Glutamyl Transferase