Exam 1 (Enzymes, Carbohydrates, Lipids) Flashcards by Tabatha O'Keefe

What are the two uses of enzymes in the clinical lab:

aid in dx

* used as reagents

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Enzymes are usually only released when tissue is ______:

damaged

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List the 6 categories of enzymes based on function:

*Oxidoreductases
*Transferases
*Hydrolases
*Lipases
*Isomerases
*Ligases
(Oh to have lived in Lisbon)

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Many of the pathological conditions seen in the lab occur in what categories of enzymes:

the first 3

oxidoreductases
transferases
hydrolases

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Enzymes are measured in ____, which means:

*one IU = amount of enzyme that will catalyze the transformation of 1 umol of substrate/min

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What type of reaction is used for LDH and what is being measured:

Coupled enzymatic (Urease, GLDH)
Measures amount of conversion of NADH to NAD (340nm)
-so actually measuring the enzyme activity of LDH, its ability to convert nadh to nad–

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Since ALKP can be increased in both bone or liver/biliary disease, what test can be used to distinguish:

5’-Nucleotidase

*will NOT be increased in bone disease

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5’-Nucleotidase can distinguish bone from liver disease, it would be increased in which one:

Increased in liver disease

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This enzyme is found in liver, intestine, bone, spleen, placenta, kidney:

Alk Phos

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This enzyme would be present in higher values in children, adolescents, and pregant women:

Alk Phos

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Very high values of Alk Phos would likely indicate:

Extrahepatic obstruction

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This enzyme would be elevated in biliary tract obstruction, hepatocellular disease, bone disease, and hyperparathyroidism:

Alk Phos

also ACP

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Alk Phos has isoenzymes that are specific to these:

Bone
Liver
Intestine
Placenta

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Alk Phos isoenzymes are sensitive to these factors:

Storage temp

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Which ALKP isoenzyme is the only heat stable form:

Placenta

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Which ALKP isoenzyme is heat labile:

Bone

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How do you differentiate bone vs liver ALKP isoenzymes in the lab:

heat inactivation (56 degrees for 10mins)
If <20% activity = bone
*incubate with Nuraminidase

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ALKP enzyme activity is highest in this pH:

alkaline

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This enzyme is present in prostate, RBC, Liver, Kidney, Plts:

ACP

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Optimal pH for ACP:

acidic

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Is ACP as sensitive as PSA as a marker for prostate cancer:

No. It is not specific to just prostate.

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T/F GGT can help differentiate between bone and liver dysfunction when ALKP is elevated:

True

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In bone disease, ALKP will be ____, and GGT will be ____:

ALKP high

GGT normal

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In obstruction, ALKP will be _____, and GGT will be __:

ALKP high

GGT high

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In liver disease, ALKP will be ___, and GGT will be ____:

ALKP normal or slightly elevated | GGT elevated

Associate the alternative test method, Bowers-McComb, with this enzyme:

ALKP

This enzyme is most specific to liver:

ALT

ALT > AST =

viral hepatic disorders

When is the enzymatic kinetic method for ALT and AST called:

Method of Henry

What is the ALT:AST ratio called:

DeRritis Ratio

ALT is synonymous with this name:

SGPT | serum glutamic-pyruvate transferase

AST is synoymous with this name:

SGOT | serum glutamic-oxaloacetic transferase

This was an 'old school' marker for MI:

AST

What is Method of Henry:

Enzymatic kinetic method for measuring ALT and AST

AST > ALT =

alcohol or drug related hepatic disorder | *also possible in carcinoma or cirrhosis

This enzyme can be elevated in hepatoceullar disorders, muscular dystrophy, MI, pulmonary embolism, CHF:

AST

This enzyme is elevated in pernicious/megaloblastic/hemolytic anemias:

LDH

What are the forward and reverse methods to measure LDH, and which is most popular:

Forward: lactate-->pyruvate (most popular) Reverse: pyruvate-->lactate

Why is the Forward method (lactate to pyruvate) the most popular for measuring LDH:

It's not subject to inhibitors and is more linear

T/F LDH can also be measured in body fluids:

True

What is the normal body fluid: serum ratio:

1:2

LDH is normally higher or lower in body fluid than serum:

lower in body fluid

LDH ratio of 1:2 or less =

transudate

LDH ratio greater than 1:2 =

exudate

Which is seen in carcinoma, hodgkins, leukemia -- transudate or exudate:

Exudate

Which LDH isoenzyme is most specific for the heart:

LD1 | LD1 higher than LD2 indicates an LD flip, significant for MI

List the organs associated with the LDH enzymes:

``` LD1: heart, RBC LD2: kidney, renal cortex LD3: lung, spleen, pancreas, lymphs LD4: liver, skeletal muscle LD5: skeletal muscle ```

List the normal height pattern of LDH isoenzymes in order from highest to lowest:

``` LD2 LD1 LD3 LD5 LD4 ```

When would you see an increase in both LD4 and LD5:

liver disease | skeletal muscle disease

What would happen to the LD peaks in Mono:

LD3 would be significantly increased | LD4/5 moderately increased

An LDH isoenzyme pattern in circulatory shock would look like:

LD1-4 very decreased | LD5 significantly increased

In liver or skeletal muscle disease, which LD peaks would you expect to be increased:

LD4 and 5

This enzyme would be elevated in MI, CVA, muscle trauma, inflammation or damage:

This is the first enzyme to increase after an MI:

This enzyme is the most sensitive to muscle damage, with highest elevations seen in skeletal muscle disease:

What are the 3 CK isoenyzmes and what are they specific for:

CKMM - muscle CKMB - heart CKBB - brain

What is another method, besides using CK isoenzymes, for distinguishing if elevated CK is due to MI or skeletal muscle disease or damage:

Oliver-Rosalski method

This CK isoenzyme is most sensisitive for muscle disease/damage:

CKMM

What is the CK Index:

(CKMB/CK) x 100

CK index >6 =

cardiac origin

CK index <3 =

skeletal muscle

What disorders will all have very high CK and CKMB, but not be a cardiac problem:

* Muscular dystrophy * Rhabdomyolysis * Traumas * *****CK Index will help distinguish*****

List the 3 enzyme markers used for MI:

CK AST LDH

Which enzyme elevates first and highest with MI:

Which enzymes elevate 2nd and 3rd in MI:

2nd- AST | 3rd - LDH

Which enzyme stays elevated longest as MI marker:

LDH

Which MI marker enzyme is the first to return to normal after MI:

CK | first to rise, first to fall

These two enzymes are often used to assess pancreatic conditions:

AMY | LIP

Will both AMY and LIP be increased in chronic pancreatitis?

No. only LIP will be increased.

Will both AMY and LIP be increased in acute pancreatitis:

Yes.

T/F Increase in AMY alone is non-specific:

true, must run with LIP and both be elevated to dx acute pancreatitis

This enzyme breaks down starch/glycogen in pancreas/salivary glands:

Amylase (AMY)

This enzyme breaks down triglycerides in pancreas (also stomach and small intestine):

Lipase (LIP)

This enzyme would be elevated in acute pancreatitis, duodenal/peptic ulcers, intestinal obstructions, and acute choecystitis:

LIP

This enzyme would be elevated in acute pancreatitis, mumps, and salivary gland irritation:

AMY

You can see false elevations in this enzyme due to opiates, and false decreases due to elevated trigs:

AMY

Cherry and Crandall method associated with this enzyme:

LIP

Elevated ALKP with normal 5' nucleotidase indicates problem with:

bone

Elevated CK, with CK index value <3 indicates this:

muscle disease

What would the AST:ALT ratio be in cirrhosis:

AST > ALT

What enzyme is increased during pregnancy?

ALKP | Due to placenta

Liver cancer would show increases in these 3 enzymes:

* ALT * AST * ALKP

What would be significantly elevated in obstruction:

*ALP *GGT (slight increases in ALT and AST)

Glycogenesis/genolysis/lysis all take place here:

Liver

Carbs must be broken down into this form before it can be absorbed in blood stream:

monosaccharide

Which two monosaccharides get further broken down into glucose:

Fructose | Galactose

Metabolism of glucose molecule to pyruvate or lactate for production of energy:

Glycolysis

Formation of glucose-6-phosphate from noncarbohydrate sources:

Gluconeogenesis

Breakdown of glycogen to glucose for use as energy (Glycogen-->G-6-P):

Glycogenolysis

Conversion of glucose to glycogen for storage:

Glycogenesis

Conversion of carbohydrates to fatty acids:

Lipogenesis

Decomposition of fat:

Lipolysis

What enzyme converts glucose to G6P:

Hexokinase

After glucose enters cells, it follows one of 3 pathways, name them:

1) Embden-Meyerhof 2) Hexose-Monophosphate 3) Glycogenesis

Which pathway stores glucose for future energy needs:

glycogenesis

This pathway breaks down glucose into pyruvate/lactate-->acetyl coA-->TCA cycle:

Embden Meyerhof

In which pathway is NADPH formed:

Hexose-Monophosphate

What is the end product of anaerobic pathway:

Lactate

Hormone that decreases plasma glucose, promotes uptake by cells, storage and conversion to lipids of excess glucose (beta cells in pancreas):

Insulin

Hormone responsible for increasing plasma glucose (alpha cells in pancreas):

Glucagon

What is released from the alpha cells in the pancreas when blood glucose is LOW:

Glucagon

This increases glycogenolysis and gluconeogenesis:

Glucagon

This decreases glycogenolysis:

Insulin

What are some causes of hypoglycemia:

overhydration hepatic dysfunction insulinoma G6PD

What are some causes of hyperglycemia:

lack of insulin insulin resistance loss of insulin release control

Diabetes affects ___% of the puplation, ___% of these are >65 years old:

3% | 10%

____ takes up ~10-12% of total annual health care budget:

Diabetes

This disease is not a 'true' diabetes, but is caused by trauma or injury to pineal gland:

Diabetes insipidus

List the 4 types of Diabetes:

Type 1 Type 2 Gestational Insipidus

Carbohydrates-->glucose--> :

pyruvate-->acetyl CoA-->TCA cycle

Lipids-->fatty acids--> :

Acetyl CoA | not as efficient as carbs though

Proteins-->amino acids--> :

pyruvate-->acetyl CoA

In diabetes, glucose cannot enter cells, so what happens:

Cells turn to fatty acids and proteins for enerrgy, leads to further increase of blood glucose. (cholesterol and ketone bodies also increase)

In ketoacidosis, which ketone body is in highest concentration:

Beta hydroxybuterate

What is used to test for ketoacidosis:

Nitroprusside test

What does the Nitroprusside test for and how:

* positive indicates ketoacidosis | * tests for acetoacetic acid, will react with nitroprusside and turn purple if present

Describe how ketoacidosis causes vision and renal problems and increase risk of CVD:

glucose binds to proteins, enhancing lipoprotein deposits increase CVD risk--- capillaries thicken and occlude microvessels

In ketoacidosis, increase in glucose will increase sorbitol, which increases osmotic pressure in cells, drawing water to them, resulting in :

nerve damage | diabetic neuropathy

Decreased blood pH from ketoacidosis results in:

oxidative damage

List the 3 methods for testing fasting glucose:

1) Glucosoxidase 2) Hexokinase 3) Copper reduction

Which fasting glucose testing method is used for urine samples:

Copper reduction

This testing method for fasting glucose is a highly specific coupled rxn that measures rate of NADPH produced (340nm):

hexokinase

This testing method for fasting glucose is subject to pos and neg interference:

Glucosoxidase

This testing method for fasting glucose can be falsely decreased due to increased bili/uric acid/ascorbic acid---- can be falsely increased due to bleach interferences (oxidizers):

Glucosoxidase

In Hexokinase test for fasting glucose, amount of NADPH produced is ______ to glucose present in sample:

proportional

Venous samples in Heparin, EDTA, Fluroide, Oxalate, and Citrate may be used for this test:

Fasting glucose

What is important to note if testing whole blood (finger stick) for fasting glucose:

values will ~11% lower than venous blood

T/F Bacterial infections will cause a greater decrease in blood glucose levels in venous blood samples (post draw):

True | Normal decrease is 5-7%/hour if not separated. greater w/ bacterial infection.

Will capillary blood sample have higher glucose level right after a meal?

Yes | Important to remember if comparing capillary sample to venous sample.

Diabetes dx may be missed if fasting sample tested in the ___:

PM. | Fasting glucose has diurnal variation- highest levels in the AM.

When will glucose appear in urine and why:

Will appear in urine when renal threshold is exceeded . (~200mg/dL)

What is the difference between glycated and glycosylated Hgb:

Glycated: permanently bound Glycosylated: Not permanent, is reversible

This test can monitor blood glucose over a 3 month window:

HgbA1C

Optimal HgbA1C level is:

<6.5

When glucose is permanently bound to heme A1C protein, and rxn is not reversible:

Glycated

``` List the criteria for diabetes dx for the following tests- A1C: FPG: OGTT: Random PG: ```

A1C >/= 6.5% FPG >/= 126 mg/dL OGTT >/= 200 mg/dL RPG >/= 200 mg/dL

Glucose + hemoglobin =

HgbA1C | glycated/glycosylated hgb

This is an early indicator of nephropathy, and testing for it is recommended yearly on known diabetics:

Microalbumin

How is microalbumin measured:

Directly or dipstick

What must be done with venous blood right away when being used to test fasting glucose:

separate or test right away | glycolysis will continue in tube after draw, reducing glucose levels 5-7% per hour if not separated

What is the significance of testing CSF for glucose:

It may be decreased in infection | normal 40-80 mg/dL

Test where glucose reduces cupric ion to cuprous ions to cuprous oxide-- color changes occur in this exothermic rxn:

Copper reduction | fasting glucose for urine test

T/F Sleep deprivation affects insulin sensitivity:

True.. Leads to metabolic disorders such as metabolic syndrome, diabetes..

Lipids are composed of ___, ___, and ___. May also contain ____ and ____:

Carbon, Hydrogen, Oxygen | Nitrogen, Phosphorous

Lipids must bind to _____ for transport in body:

lipoproteins

These types of lipids provide energy:

Trigs | Fatty acids

These types of lipids provide structure:

Phospholipids and cholesterol present in cell membranes

List the 3 main functions of lipids:

1) energy 2) structure 3) insulation

List the 4 lipids present in plasma:

1) triglycerides 2) cholesterol 3) phospholipids 4) fatty acids

What are the main lipids, usually the only ones tested for in the lab:

trigs and cholesterol

This is a precursor to hormones, bile salt, and vitamin D:

cholesterol

Two types of cholesterol and percentage they provide to total cholesterol level:

* Exogenous (diet), animal fats, only 1/3 to 1/2 is absorbed, the rest is excreted * Endogenous (synthesized by liver), supplies 70% of total cholesterol

How much of our total cholesterol is endogenous:

70% (synthesized by liver)

Cholesterol reference range:

150-250 mg/dL

Females typically have lower cholestTwo typeserol than men until this stage:

menopause

How is cholesterol related to T4, insulin, and estrogens:

Inversely

Two types of trigs:

* endogenous (synthesized in liver and adipose tissue) | * exogenous (diet)

What are the two functions of lipids:

1) Storage | 2) Energy

How are lipids converted from storage to be used for energy:

Hydrolyzed by lipase to make fatty acids, which will bind to albumin for transport to cells that need energy

Optimal triglyceride levels: | Reference range for trigs:

<100 mg/dL 100-200 mg/dL (just because its a reference range doesnt mean its optimal/healthy)

What can be a complication of severe hypertriglylceridemia:

pancreatitis

Increased fatty acids and triglycerides are associated with:

hyperglycemia

Fatty acids are mainly provided by ___, and do/do not greatly contribute to plasma lipid level:

* diet | * do not

These act as lung surfactants, are important in coagulation, part of myelin sheath,and regulate cell permeability:

phospholipids

These are major components of lipoprotein outer shell, and hold apoprotein to lipoprotein:

phospholipids

T/F Phospholipids are quantified in the lab:

False

Phospholipids as surfactant (Lecithin) can be measured via:

L/S ratio in amniotic fluid | lung maturity

This coats embryonic alveolar sac lining in lungs, keeps them from collapsing, and is measured how:

* Lecithin (phospholipid) | * L/S ratio in amniotic fluid

T/F Phospholipids mostly come from diet:

False. | They are mostly synthesized in liver.

List the 5 classes of lipoproteins, from least to most dense:

* Chylomicrons * VLDL * LDL * HDL * Lipoprotein A

These are found on the surface of lipoproteins, help maintain structure and play a role in cell receptors and inhibitors to enzymes that modify the lipoprotein structure:

apolipoproteins

Apolipoprotein A1 is the major protein in ____:

HDL

What are the two kinds of Apolipoprotein B:

* B100 (LDL and VLDL) | * B48 (chylomicrons)

B100 is found here:

LDLD and VLDL

B48 is found here:

chylomicrons

Apo-E found in many lipoproteins:

LDL, VLDL, HDL

These transport exogenous trigs and dietary lipids to hepatic and peripheral cells:

chylomycroms

This is formed by lypolysis of VLDL, and primary apolipoprotein is B100:

LDL

Which is larger, LDL or VLDL:

VLDL

When LDL infiltrates extracellular space of vessels, is oxidized and taken up by macrophages-->

Foam cells

High levels of this lipoprotein is associated with increased risk of stroke, rather than heart disease:

LP-A

Which is synthesized by liver and intestine, LDL or HDL:

HDL | DLD formed by lypolysis of VLDL

What two things contribute to the milky appearance of a lipemic sample:

VLDL | Chylomicrons

After refrigeration, which lipoprotein would float to the top in a lipemic sample:

Chylomycrons | largest and least dense

Which lipoprotein is responsible for most turbidity in fasting hyperlipidemia samples:

VLDL | large particles scatter light and cause turbidity

Which lipid panel value is calculated, and what is the equation named/used:

LDL Friedewald equation LDL= total chol - HDL - (trigs/5)

What was the historical measurement for cholesterol/trigs:

Liebermann-Burchard rxn (2 step precipitation) (uses acetic anhydride, colorimetric)

Can you use the Friedewald equation if trigs >400?

What is the current method for cholesterol/trig measurement:

Enzymatic (and colorimetric) | better specificity, less interference

Measuring these involves essentially an assay of glycerol:

Trigs

Appearance of serum can predict trig level- Clear: Hazy: Milky:

Clear <200 Hazy >300 Milky >600

Is the current method of cholesterol/trig measurement recommended for research purposes?

No. Lacks specificity in liver/renal patients. Frequent modifications to reagents by manufacturer.

``` What are the optimal levels for the following- LDL: HDL: Trigs: Total Chol: Total chol/HDL ratio: ```

``` LDL: <100 HDL: >60 Trigs: <150 Total Chol: <200 Total chol/HDL ratio: <4 ```

Why could a lipid panel sample appear orange:

Increased LDL

List some important specifics regarding testing for lipid panels:

* Maintain normal diet for 3 days prior * Do not test during illness * Fast at least 12 hrs, no alcohol 24 hrs * Avoid hemoconcentration * EDTA will be 4-5% lower than serum

If you have a lipemic sample to be tested for lipids, would you dilute or ultracentrifuge:

Dilute. | Ultracentifuge will spin out the trigs

Exam 1 (Enzymes, Carbohydrates, Lipids) Flashcards

(196 cards)