Lipid Profile

Question 1

What is the Total cholesterol test used for and what are the normal values?

Answer 1

Cholesterol testing used to determine risk for coronary artery disease and for evaluation of hyperlipidemias

Normal < 200 mg/dL

Cholesterol can vary day to day by 15% and may show an 8% difference within the same day

Question 2

Total cholesterol is not a good preditor of heart disease by itself. What else is looked at to determine risk?

Answer 2

Total cholesterol done as part of a lipid profile as well as looking at other risk factors:
Gender, age, blood pressure, diabetes, smoker, etc.

Question 3

What is the main lipid associated with arteriosclerotic vascular disease?

Answer 3

LDL

Question 4

Where does most cholesterol come from and what is produced from it?

Answer 4

Most comes from foods of animal origin and is metabolized by the liver to its free form and is then transported by lipoproteins.

Required for production of steroids, sex hormones, bile acids, and cellular membranes

Question 5

Cholesterol is bound to LDL and HDL. What % of cholesterol is bound to each one?

Answer 5

75% is bound to low density lipoproteins (LDL)

25% is bound to high density lipoproteins (HDL).

Question 6

Which lipoprotein is most directly associated with increased risk for CAD?

Answer 6

LDL

Question 7

This algorithm determines the risk for an ischemic event over the course of the next decade.

Answer 7

Framingham Coronary Prediction algorithm

This algorithm takes into account:

AGE, Total Cholesterol, HDL cholesterol, Blood pressure, diabetes, smoker

Question 8

Total cholesterol interfering factors

Answer 8

Pregnancy associated with elevation

Oophorectomy and postmenopausal states associated with elevation

Recumbent position associated with decreased levels

Drugs that cause increased levels include anabolic steroids, beta blockers, corticosteroids, oral contraceptives, thiazide diuretics

Drugs that cause decreased levels include androgens, captopril, clofibrate, colestipol, niacin, and statins

Question 9

Causes of Increased Total cholesterol

Answer 9

Familial hypercholesterolemia and familial hyperlipidemia – enzymatic deficiencies in lipid metabolism

Hypothyroidism, uncontrolled diabetes mellitus, nephrotic syndrome, pregnancy, high cholesterol diet, hypertension, MI, atherosclerosis, biliary cirrhosis, stress

Question 10

Causes of decreased level of Total Cholesterol

Answer 10

Malabsorption, malnutrition, and advanced cancer – dietary intake is decreased so fat levels and cholesterol levels fall

Hyperthyroidism, cholesterol lowering medications, pernicious anemia, hemolytic anemia, sepsis, liver disease, and MI

Question 11

What are the four types of lipoproteins?

Answer 11

HDL

LDL

VLDL

Chylomicrons

Question 12

What are lipoproteins predictors of and what are the normal ranges?

Answer 12

Accurate predictor of heart disease. Performed to identify people at risk for developing heart disease and to monitor therapy if abnormalities are found.

Normal findings
HDL: Male: > 45 mg/dL, Female: > 55 mg/dL
LDL: < 130 mg/dL
VLDL: 7-32 mg/dL

Question 13

What is the function of Lipoproteins in the body?

Answer 13

Lipoproteins are proteins in the blood that transport cholesterol, triglycerides, and other insoluble fats. They are markers indicating levels of lipids in the bloodstream and are classified by their measured density.

Question 14

What is the order of lipoproteins from largest and least dense(more fat) to smaller and most dense(more protein)

Answer 14

Chylomicron

VLDL

LDL

HDL

Question 15

What is the function of chylomicrons?

Answer 15

carry triacylglycerol (fat) from intestines to liver, skeletal muscle, and adipose tissue

Question 16

What is the function of VLDL’s?

Answer 16

carry newly synthesized triacylglycerol from liver to adipose tissue

Question 17

What is the function of LDL’s?

Answer 17

carry cholesterol from liver to cells of the body – “bad cholesterol”

Question 18

What is the function of HDL’s?

Answer 18

collect cholesterol from body’s tissues and vascular endothelium (reverse cholesterol transport provides protective effect against heart disease) and brings it back to the liver for excretion – “good cholesterol”

Question 19

This lipoprotein measurement is an independent inverse risk factor for CAD

Answer 19

Total HDL is an independent inverse risk factor for CAD. Levels < 35 mg/dL increase risk for CAD while levels > 60 mg/dL are protective

Question 20

This lipoprotein is cholesterol rich and deposits cholesterol in the lining of the blood vessels?

Answer 20

LDLs are cholesterol rich, but most cholesterol carried by LDL gets deposited into the lining of the blood vessels and has increased risk for CAD and peripheral vascular disease. High levels of LDL are atherogenic.

Question 21

This lipoprotein mainly carrier triglycerides.

Answer 21

VLDL carries small amounts of cholesterol but mainly carries triglycerides.

Question 22

This lipoprotein can be converted to LDL by lipoprotein lipase in skeletal muscle.

Answer 22

VLDLs are associated with increased risk for CAD as they can be converted to LDL by lipoprotein lipase in skeletal muscle

Question 23

Interfering factors for Lipoprotein mesaurements.

Answer 23

Smoking and alcohol decrease HDL

Binge eating can alter lipoprotein levels

HDL values are age and sex dependent

HDL values and cholesterol decrease for up to 3 months after an MI

HDL is elevated with hypothyroid and decreased in hyperthyroid

Drugs can alter lipoprotein levels:

Beta blockers increase triglycerides, decrease HDL , decrease LDL size

Alpha blockers decrease triglycerides, increase LDL, increase LDL size

Dilantin increases HDL

Steroids increase triglycerides

Estrogens increase triglycerides

Question 24

Causes of increased HDL

Answer 24

Familial HDL lipoproteinemia
Excessive exercise – HDL can rise with chronic exercise for 30 minutes 3 times a week

Question 25

Causes of decreased HDL

Answer 25

Metabolic syndrome – decreased HDL, increased triglycerides, elevated fasting glucose, high blood pressure, and abdominal obesity

Familial low HDL

Hepatocellular disease (hepatitis, cirrhosis) – HDL normally made in liver

Hypoproteinemia (nephrotic syndrome, malnutrition) – HDL not made and levels fall due to loss of proteins

Question 26

Causes of increased LDL and VLDL

Answer 26

Familial LDL lipoproteinemia

Nephrotic syndrome – loss of protein diminishes plasma oncotic pressures, which stimulates hepatic synthesis of LDL

Glycogen storage diseases – VLDL synthesis increased and excretion decreased

Hypothyroidism – VLDL and LDL catabolism diminished so levels rise

Alcohol consumption

Chronic liver disease (hepatitis, cirrhosis) – liver normally catabolizes LDL

Hepatoma – normal inhibition of LDL synthesis by eating dietary fats doesn’t occur

Gammopathies (multiple myeloma) – high levels of gamma globulins (IgG and IgM) attach to VLDL and LDL to decrease metabolism

Familial hypercholesterolemia – LDL receptors are altered, and LDL is produced at an increased rate
Cushing syndrome – VLDL synthesis is increased and converted to LDL

Apoprotein C-II deficiency – genetic defect with deficiency of lipoprotein lipase, so VLDL and chylomicrons accumulate

Question 27

Causes of decreased LDL and VLDL

Answer 27

Familial hypoproteinemia

Hypoproteinemia (malabsorption, severe burns, malnutrition)

Hyperthyroidism – catabolism of LDL and VLDL is increased

Question 28

What is the triglyceride (TG) test used for and what are the normal ranges?

Answer 28

Test is used to identify risk of developing CAD, also part of lipid profile and is performed on patients with suspected fat metabolism disorders

Normal range:

Males 40-160 mg/dL

Females 35-135 mg/dL

Question 29

What are Triglycerides and where are they produced?

Answer 29

TG are a form of fat in the bloodstream and are transported by VLDL and LDL.

TG is produced in the liver using glycerol and other fatty acids and act as a storage source for energy

When levels are high they are deposited in fatty tissues.

Question 30

Most of the fat in the body is in what form?

Answer 30

Triglycerides

Question 31

Interfering factors of triglycerides

Answer 31

Ingestion of fatty meals may elevate TG levels

Alcohol ingestion may elevated TG by increasing production of VLDL

Pregnancy may increase levels

Drugs that increase TG levels are estrogens and oral contraceptives

Drugs that decrease TG levels are ascorbic acid, clofibrate, colestipol, fibrates, and statins

Question 32

Causes of increased triglycerides

Answer 32

Glycogen storage disease (von Gierke disease) – VLDL synthesis is increased and catabolism decreased

Familial hypertriglyceridemia

Apoprotein C-II deficiency – lipoprotein lipase deficiency leads to TG accumulation

Hyperlipidemias

Hypothyroidism – TG catabolism decreased

High carbohydrate diet – excess carbs converted to TG

Poorly controlled diabetes – increased synthesis of VLDL and decreased catabolism leads to increased TG levels

Nephrotic syndrome – loss of proteins decreases oncotic pressure to stimulate synthesis of VLDL and LDL

Chronic renal failure – high insulin levels as insulin is normally excreted by the kidney. Insulin increases lipogenesis so TG levels rise. Also have deficiency of lipoprotein lipase that clears TG from the blood

Question 33

Causes of decreased triglycerides

Answer 33

Malabsorption syndrome – poor fat absorption from the GI tract

Abetalipoproteinemia – malabsorption of fat and defective synthesis of apoprotein B (TG carrying lipoproteins)

Malnutrition – diminished fat in the diet

Hyperthyroidism – catabolism of VLDL is increased so TG levels decrease