Exam 1 (Enzymes, Carbohydrates, Lipids) Flashcards
What are the two uses of enzymes in the clinical lab:
- aid in dx
* used as reagents
Enzymes are usually only released when tissue is ______:
damaged
List the 6 categories of enzymes based on function:
*Oxidoreductases
*Transferases
*Hydrolases
*Lipases
*Isomerases
*Ligases
(Oh to have lived in Lisbon)
Many of the pathological conditions seen in the lab occur in what categories of enzymes:
the first 3
- oxidoreductases
- transferases
- hydrolases
Enzymes are measured in ____, which means:
IU
*one IU = amount of enzyme that will catalyze the transformation of 1 umol of substrate/min
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–
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
5’-Nucleotidase can distinguish bone from liver disease, it would be increased in which one:
Increased in liver disease
This enzyme is found in liver, intestine, bone, spleen, placenta, kidney:
Alk Phos
This enzyme would be present in higher values in children, adolescents, and pregant women:
Alk Phos
Very high values of Alk Phos would likely indicate:
Extrahepatic obstruction
This enzyme would be elevated in biliary tract obstruction, hepatocellular disease, bone disease, and hyperparathyroidism:
Alk Phos
also ACP
Alk Phos has isoenzymes that are specific to these:
Bone
Liver
Intestine
Placenta
Alk Phos isoenzymes are sensitive to these factors:
Storage temp
pH
Which ALKP isoenzyme is the only heat stable form:
Placenta
Which ALKP isoenzyme is heat labile:
Bone
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
ALKP enzyme activity is highest in this pH:
alkaline
This enzyme is present in prostate, RBC, Liver, Kidney, Plts:
ACP
Optimal pH for ACP:
acidic
Is ACP as sensitive as PSA as a marker for prostate cancer:
No. It is not specific to just prostate.
T/F GGT can help differentiate between bone and liver dysfunction when ALKP is elevated:
True
In bone disease, ALKP will be ____, and GGT will be ____:
ALKP high
GGT normal
In obstruction, ALKP will be _____, and GGT will be __:
ALKP high
GGT high
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:
CK
This is the first enzyme to increase after an MI:
CK
This enzyme is the most sensitive to muscle damage, with highest elevations seen in skeletal muscle disease:
CK
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:
CK
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?
No
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
