(F) L1: Enzymes (Part 3) Flashcards by Kchianna Lauren Coronel

Major Clinical Enzymes

This contains zinc and is part of the glycolytic pathway
Is usually coupled with amylase in the degradation of carbohydrates

Lactate Dehydrogenase (LD)

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Lactate Dehydrogenase (LD)

It requires what coenzyme?

NAD+

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Lactate Dehydrogenase (LD)

LD has several isoenzymes which are considered what type of molecule?

Tetrameric (has 4 subunits of H and M)

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Lactate Dehydrogenase (LD) Isoenzymes

Sourced from the heart, RBCs, and kidneys

LD 1 and 2

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Lactate Dehydrogenase (LD) Isoenzymes

Sourced from the lungs, pancreas, and spleen

LD 3

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Lactate Dehydrogenase (LD) Isoenzymes

Sourced from the skeletal muscle, liver, and intestine

LD 4 and 5

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Lactate Dehydrogenase (LD)

Reference value for forward reaction (enzyme is related to the substrate)
Reference value for reverse reaction (enzyme is related to the product)

A. 100-225 U/L
B. 80-280 U/L

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Lactate Dehydrogenase (LD) Isoenzymes

These are considered to be the most abundant, most anodal, and heat stable

LD 1 and 2

LD 1: 17-27% while LD 2: 27-37%

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Lactate Dehydrogenase (LD) Isoenzymes

These are considered to be the least concentrated, least anodal, and heat labile

LD 4 and 5

LD 4: 3-8% while LD 5: 0-5%

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Lactate Dehydrogenase (LD) Isoenzymes

100% made up of H subunits

LD 1

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Lactate Dehydrogenase (LD) Isoenzymes

Made up of 25% M subunits and 75% H subunits

LD 2

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Lactate Dehydrogenase (LD) Isoenzymes

Made up of 50% M subunits and 50% H subunits

LD 3

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Lactate Dehydrogenase (LD) Isoenzymes

Made up of 75% M subunits and 25% H subunits

LD 4

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Lactate Dehydrogenase (LD) Isoenzymes

100% made up of M subunits

LD 5

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Lactate Dehydrogenase (LD) Other Isoenzymes

This is seen in individuals who frequently drink alcohol which contains methanol or ethylene glycol
This appears as a 6th band in an electrophoresis medium
Is increased in cases of drug hepatotoxicity and obstructive jaundice
It also appears in patients with arteriosclerotic failure

Alcohol Dehydrogenase (LD 6)

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Lactate Dehydrogenase (LD) Other Isoenzymes

This consists of C subunits
Only seen in spermatozoa and semen and never in serum or in cases of seminoma

LD with 4C Subunits

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Lactate Dehydrogenase (LD) Specimen Considerations

This substrate provides greater specificity
This substrate is used for detecting LD 1 activity

A. Pyruvate
B. A-hydroxybutyrate
C. Lactate

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Lactate Dehydrogenase (LD) Specimen Considerations

An increase in α-hydroxybutyrate activity indicates an increase in what 2 isoenzymes?

LD 1 and 2

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Lactate Dehydrogenase (LD) Specimen Considerations

LD is stable at what temperature for how many hours and is considered to be cold-labile, most especially LD 5?

RT for 48 hours

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Lactate Dehydrogenase (LD) Specimen Considerations

In cases of pleural fluid, transudates will exhibit a/an (increased/decreased) amount of LD

Decreased

Caused by physiologic reasons such as the changes in oncotic and hydrostatic pressure within the lungs; minimal intervention may be done, and is somewhat irreversible

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Lactate Dehydrogenase (LD) Specimen Considerations

In cases of pleural fluid, exudates will exhibit a/an (increased/decreased) amount of LD

Increased

Caused by pathologic reasons such as inflammation, infection, and the like; may easily be solved with multiple medical interventions

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Lactate Dehydrogenase (LD) Specimen Considerations

An increase in LD may also occur after what procedure as whole blood may contain LD?

Note: This may return to normal after 24 hours

Blood transfusion

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Lactate Dehydrogenase (LD) Specimen Considerations

Frozen samples will have a decreased value for what isoenzyme as this is cold labile?

LD 5

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Lactate Dehydrogenase (LD) Specimen Considerations

TOF: Samples should be processed within 48 hours after collection and stored at 30ºC

False (24 hours at 25ºC)

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# Lactate Dehydrogenase (LD) Methods of Analysis - It is a forward reaction with lactate as the substrate - The lactate + NAD will be acted upon by LD which produces pyruvate and NADH - Is read at 340nm at a pH of 8.8 - Most commonly used since it produces positive rates of NADH and is not affected by inhibitors

Wacker Method (Forward or Direct Reaction)

# Lactate Dehydrogenase (LD) Methods of Analysis - It is a reverse reaction with lactate as the product - Pyruvate with NADH is acted upon by LD to produce lactate and NAD - Is read at 340nm at a pH of 7.2 - The reaction is 2x faster than the other method - Is preferred for dry slide technology - Has less costly cofactors and only requires a small specimen volume

Wrobleuski and La Due Method (Reverse or Indirect Reaction)

# Lactate Dehydrogenase (LD) Diagnostic Significance Arrange the isoenzymes from most numerous to least numerous (LD 1 to 5)

1. LD 2 2. LD 1 3. LD 3 4. LD 4 5. LD 5

# Lactate Dehydrogenase (LD) Diagnostic Significance What is the order of isoenzymes in cases of acute myocardial infarctions (most numerous to least numerous)?

LD 1 to 5 (chronological or flipped pattern)

# Lactate Dehydrogenase (LD) Diagnostic Significance LD can be used to diagnose the severity or presence of AMI depending on the levels of the enzyme in the body which will exhibit the following in the presence of the disease: 1. A rise in how many hours? 2. A peak in how many hours? 3. A continuous elevated level up to how many days? A. 12 to 24 B. 10 to 14 C. 48 to 72

1. A (12-24 hours) 2. C (48-72 hours) 3. B (10-14 days)

# Lactate Dehydrogenase (LD) Diagnostic Significance LD can also be used as a marker for what to aid in the diagnosis of acute leukemia, germ cell tumors, and breast and lung malignancies?

Cancer marker

# Lactate Dehydrogenase (LD) Diagnostic Significance What isoenzymes are elevated in cases of acute leukemia, germ cell tumors, and breast and lung malignancies?

LD 2, 3, and 4 | LD 3 is the predominant isoenzyme

# Lactate Dehydrogenase (LD) Diagnostic Significance A **moderate** increase in the levels of what isoenzyme indicates acute viral hepatitis and cirrhosis?

LD 5

# Lactate Dehydrogenase (LD) Diagnostic Significance A **marked** increase in the levels of what isoenzyme indicates acute hepatic carcinoma and toxic hepatitis?

LD 5

# LD Level Indications 1. Pernicious anemia, hemolytic disorder, and megaloblastic anemia 2. Hepatic carcinoma and toxic hepatitis 3. Viral hepatitis and cirrhosis 4. Non-specific A. 10x increase in serum LD B. Elevated total serum LD C. Slight increase of serum LD D. Highest serum LD

1. D 2. A 3. C 4. B

# Increased or Decreased LD? - Anemias - AMI - Leukemia - Renal Infarction - Hepatitis - Hepatic Cancer - Muscular Dystrophy - Delirium Tremens - Malignancy - Pneumocystis Jerovecii Pneumonia

Increased

# Major Clinical Enzymes - Aka “ATP-creatine-N-phosphotransferase” - Creatine with ATP will be acted upon by this enzyme to produce creatinine phosphate and ADP - Serves as storage for creatinine phosphate in the muscle - A dimeric molecule (2 pairs of monomers: M and B)

Creatine Kinase (CK)

# Creatine Kinase (CK) What are the 4 tissue sources?

1. Brain 2. Smooth muscle 3. Skeletal muscle 4. Cardiac muscle

# Creatine Kinase (CK) Reference values for total CK: 1. For males 2. For females A. 15 to 130 U/L B. 15 to 160 U/L

1. B 2. A

# Creatine Kinase (CK) The normal value of CK-MB (isoenzyme) is how many percent less than the total CK value?

# Creatine Kinase (CK) Isoenzymes - The dominant isoenzyme in the brain, intestine, and smooth muscle - Has high molecular size - Is normally seen in neonatal sera (skulls aren't fully developed hence they seep into the circulation) but not for adults (prevented by the blood-brain barrier due to large molecular weight)

CK-BB (Brain Type)

# Creatine Kinase (CK) Isoenzymes - Predominantly seen in cardiac tissue (myocardium) which contributes to 20% of the total isoenzyme count - The reference range is less than 5ug/L

CK-MB (Hybrid Type)

# Creatine Kinase (CK) Isoenzymes - Abundantly seen in cardiac and skeletal muscles - The major isoenzyme accounting for 94-100% of the total CK amount

CK-MM (Muscle Type)

# Creatine Kinase (CK) Specimen Considerations Give the 3 inhibitors of CK

1. Urate 2. Cystine 3. Adenylate Kinase (AK)

# Creatine Kinase (CK) Specimen Considerations A hemolytic degree of greater than how many mg/L indicates the presence of Adenylate Kinase which may cause problems in the analysis?

320 mg/L

# Creatine Kinase (CK) Specimen Considerations Adenylate Kinase may be inhibited by what?

Adenosine monophosphate (AMP)

# Creatine Kinase (CK) Specimen Considerations N-acetylcysteine and magnesium ions (Mg2+) play what role?

CK activators

# Creatine Kinase (CK) Specimen Considerations This antibiotic acts as a buffer for the reaction

Imidazole

# Creatine Kinase (CK) Specimen Considerations CK is sensitive to what? (2 answers)

1. Light 2. pH | Note: It is also lost with excessive storage

# Creatine Kinase (CK) Specimen Considerations In case of a loss in CK activity, it may be restored using what? (2 answers)

Cleland's reagent and Glutathione

# Creatine Kinase (CK) Specimen Considerations 1. The more sensitive method 2. The reference method A. Electrophoresis B. CK mass unit assay

1. B 2. A

# Creatine Kinase (CK) Methods of Analysis - CK is utilized along with other enzymes such as pyruvate kinase (PK) and lactate dehydrogenase (LD) in a series of reactions wherein the initial substrates of creatine and ATP will be acted upon by CK to produce creatine phosphate and ADP - ADP will then be paired with phosphoenolpyruvate (PEP), to be acted upon by PK to produce pyruvate and ATP - Pyruvate will be combined with NADH, which will be acted upon by LD to produce lactate and NAD as the final products of the method - Products are read at 340nm at a pH of 9.0

Tanzer-Gilbarg Method (Forward or Direct Reaction)

# Creatine Kinase (CK) Methods of Analysis - This method combines CK with other enzymes such as hexokinase (HK) and LD - The initial substrates of creatine phosphate with ADP will be acted upon by CK to produce creatine and ATP - ATP will be combined with glucose to be acted upon by HK, producing ADP and G6P - G6P combined with NADP will be acted upon by LD, to produce 6-phosphogluconate with NADPH - Products are read at 340nm at a pH of 6.8 - This method is commonly used and allows for faster reactions

Oliver-Rosalki Method (Reverse or Indirect Reaction)

# Creatine Kinase (CK) Diagnostic Significance Individuals who are physically well-trained and are constantly performing strenuous activities have a/an (increased/decreased) baseline of total CK

Increased

# Creatine Kinase (CK) Diagnostic Significance A direct trauma to the muscle results to an increase of how many times the upper reference limits?

5 to 6 times

# Creatine Kinase (CK) Diagnostic Significance Bedridden patients have a/an (increased/decreased) CK activity since it is correlated with muscle movement

Decreased

# Creatine Kinase (CK) Diagnostic Significance CK serves as a sensitive indicator for what 2 conditions?

1. Acute MI 2. Duchenne muscular dystrophy

# Creatine Kinase (CK) Diagnostic Significance Duchenne muscular dystrophy increases the upper reference limit how many times over? (provides the highest elevation)

50 times

# Creatine Kinase (CK) Diagnostic Significance In cases of acute myocardial infarction, what isoenzyme is used in serodiagnostic tests (more on immunology than chemicals)?

CK-MB

# Creatine Kinase (CK) Diagnostic Significance CK-MB levels are most specific if the levels of CK-MB in the total amount of CK is greater than or equal to how many percent?

# Creatine Kinase (CK) Diagnostic Significance In cases of angina, CK-MB (is/is not) elevated

Is not (may not be caused by cardiac diseases)

# Creatine Kinase (CK) Diagnostic Significance The levels of CK-MB can be used to diagnose the severity and/or presence of AMI which may exhibit the following: 1. A rise in how many hours? 2. A peak in how many hours? 3. A decrease back to normal in how many hours? A. 4 to 8 B. 12 to 24 C. 48 to 72

1. A 2. B 3. C

# Creatine Kinase (CK) Diagnostic Significance Elevated levels of CK-MM may indicate an injury to what 2 muscles?

Skeletal and Cardiac

# Creatine Kinase (CK) Diagnostic Significance A significant (increase/decrease) of the total CK may be indicative of trauma to the skeletal muscle

Increase ## Footnote Caused by: Crush injuries, convulsions, tetany, surgical incision, and IM injection

# Increased or Decreased CK? 1. Duchenne muscular dystrophy 2. AMI 3. Hyperthyroidism 4. Pulmonary infarction 5. Reye's syndrome 6. Strenous excercise 7. IM injections 8. Cerebral vascular accidents 9. Rocky Mountain spotted fever 10. CO poisoning

Increased

# Major Clinical Enzymes - Aka “Fructose 1,6- Diphosphate Aldolase” - Fructose 1-6-diphosphate is acted upon by this enzyme to produce 2-triose phosphate - An increase of this is indicative of skeletal muscle disease, leukemia, hemolytic anemia, and hepatic cancer

Aldolase (ALD)

# Aldolase (ALD) Isoenzymes Sourced from skeletal muscles

ALD-A

# Aldolase (ALD) Isoenzymes Sourced from the liver, kidneys, and WBCs

ALD-B

# Aldolase (ALD) Isoenzymes Sourced from the brain

ALD-C

Skeletal Muscle or Brain Marker? - CK-MM - AST - ALD-A - LD 4 - LD 5

Skeletal Muscle Marker

Skeletal Muscle or Brain Marker? - CK-BB - ALD-C

Brain Marker

# Major Clinical Enzymes - A phosphoric monoester of hydrolase - Its major tissue source is the liver and serves as a marker for hepatobiliary disease, secondary post-hepatic diseases, and infiltrative lesions of the liver

5' Nucleotidase (5'N)

# 5' Nucleotidase (5'N) TOF: 5'N is very specific and provides promising specificity in diagnosing hepatic diseases

True

# 5' Nucleotidase (5'N) What is the reference value?

0 to 1.6 units

# Major Clinical Enzymes These methods of analysis are used for what enzyme? - Dixon and Purdon - Campbell - Belfield and Goldberg

5' Nucleotidase (5'N)

# Major Clinical Enzymes - This functions by transferring glutamyl groups between peptides and amino acids - Major tissue sources include the liver, biliary duct, kidney, prostate, and pancreas - Is greatly affected by drugs and other substances (Warfarin, Phenobarbital, and Phenytoin therapy) that affects cell membranes and microsomal functions | Note: The medications control seizures (psychoactive drugs)

Gamma Glutamyl Transamine Peptidase/Transferase (GGT)

# Gamma Glutamyl Transamine Peptidase/Transferase (GGT) What is the substrate?

Gamma-glutamyl-p-nitroanilide

# Gamma Glutamyl Transamine Peptidase/Transferase (GGT) Reference Values: 1. For males 2. For females A. 5 to 30 U/L B. 6 to 45 U/L

1. B 2. A

# Major Clinical Enzymes These methods of analysis are used for what enzyme? - Szass - Rosalki and Tarrow - Orlowski

Gamma Glutamyl Transamine Peptidase/Transferase (GGT)

# GGT Diagnostic Significance GGT determination is useful in differentiating the causes of an increase in what other enzyme since it is sourced from a variety of tissues?

Alkaline Phosphatase (ALP)

# GGT Diagnostic Significance GGT is an important marker/indicator for the ff. except: A. Secondary post-hepatic diseases B. Alcoholism C. Cardiac diseases D. Pancreatic disorders E. Prostate disorders

C. Cardiac diseases

# Major Clinical Enzymes - This reflects the synthetic function of the liver - Considered as an antixenobiotic enzyme which removes the benzyl group from cocaine - Serves as a marker for insecticide or pesticide poisoning, especially organophosphate poisoning, which is indicated by a decreased amount of it - A decrease may also indicate acute hepatitis, cirrhosis, metastatic hepatocarcinoma, malnutrition, and organophosphate poisoning | Antixenobiotic: for detoxification

Pseudocholine Esterase (PChE)

# Pseudocholine Esterase (PChE) PChE is involved in the metabolism of succinylcholine which is what type of drug?

Anticholinergic drugs (monitors the effect of muscle relaxants)

# Pseudocholine Esterase (PChE) TOF: In cases of acute toxicity, the enzyme involved is PChE but in cases of chronic exposure to toxins, the enzyme involved is the Acetyl cholinesterase (AChE)

True

# Pseudocholine Esterase (PChE) What are its 3 tissue sources?

Liver, Myocardium, and Pancreas

# Pseudocholine Esterase (PChE) What is the reference value?

Between 0.5 to 1.3 pH units

# Major Clinical Enzymes These methods of analysis are used for what enzyme? - Ellman - Potentiometric

Pseudocholine Esterase (PChE)

# Major Clinical Enzymes - Aka “peptidyldipeptidase A /Kininase II” - A hydrolase enzyme that converts angiotensin I to angiotensin II in the lungs - Serves as an indicator for neuronal dysfunction in infants - Its tissue sources are the lungs, macrophages, and epithelioid cells - Used in the diagnosis and monitoring of sarcoidosis

Angiotensin Converting Enzyme (ACE)

# Angiotensin Converting Enzyme (ACE) ACE inhibitor drugs (increase/decrease) the BP of an individual

Decrease

# Angiotensin Converting Enzyme (ACE) Increased or Decreased? - Sarcoidosis - Multiple sclerosis - Addison's disease - Acute and chronic bronchitis - HIV infection - Leprosy

Increased

# Major Clinical Enzymes - It functions as a transport protein by carrying copper throughout the body - It is a marker for hepatolenticular diseases such as that of Wilson’s disease

Ceruloplasmin

# Major Clinical Enzymes A marker for hepatobiliary diseases

Ornithine Carbamoyl Transferase (OCT)

# Major Clinical Enzymes - This maintains NADPH in its reduced form in the RBC - A usual enzyme in the glycolytic pathway and other glucose methods - Used as a newborn screening marker since there are newborns that lack this - Its tissue sources are the adrenal cortex, RBCs, and lymph nodes

Glucose-6-Phosphate-Dehydrogenase (G6PD)

# Glucose-6-Phosphate-Dehydrogenase (G6PD) This drug, that induces hemolytic anemia, increases the amount of G6PD in the plasma

Primaquine

# Glucose-6-Phosphate-Dehydrogenase (G6PD) What specimens (2) are usually used for analysis?

1. Red cell hemolysate 2. Serum

# Glucose-6-Phosphate-Dehydrogenase (G6PD) A/an (increased/decreased) G6PD may be caused by AMI and megaloblastic anemia

Increased

# Glucose-6-Phosphate-Dehydrogenase (G6PD) Reference Values: 1. In hemoglobin 2. In packed RBCs A. 10 to 15 U/g B. 1,200 to 2,000 mU/mL

1. A 2. B

(F) L1: Enzymes (Part 3) Flashcards

(96 cards)