Lipid Panel

Background

We hear it everyday-Eat more fiber to reduce your cholesterol! Any modification of your cholesterol levels must begin with the laboratory testing. The laboratory testing for cholesterol has become increasingly complicated and is now a veritable alphabet soup of different fat proteins. Collectively, they are known as lipids. The lipid panel usually includes the following:

Cholesterol

HDL

LDL

Triglycerides

Additional tests may include:

VLDL

Apolipoprotein A-1 and B

Homocysteine

C-reactive protein

ANALYTICAL METHOD

LDL

Most methodes have derived this using the Friedewald formula wich depends upon the total cholesterol, HDL, and TG-use of this formula in postprandial samples may underestimate levels by as much as 20%-the reason is mobilization of cholesterol out of LDL and HDL and into chylomicrons and VLDL

Direct measurement should be able to measure non fasting samples

BIOCHEMICAL THEORY See below

IDEAL TESTING STATE Nine hour fast but a 12-14 hour fast after a low-fat, low-calorie meal, with no intake of alcohol for 24 hours is preferable

REFERNCE RANGE
JAMA 2001;285:2486-2497

Current Recommendations for Adults from the National Cholesterol Education Program (NCEP) Third Report

Total Cholesterol (TC)
>240 mg/dL
>6.2 mmol/L

Low Density Lipoprotein (LDL-C)

Optimal <100 mg/dL
Near or above optimal (100-129 mg/dL)
Borderline High (130-159 mg/dL)
High (160-189 mg/dL)
Very High (>/= 190 mg/dL)

High Density Lipoprotein (HDL)
>40 mg/dL

Triglyceride (TG)
>/=150 mg/dL borderline
>/=400 mg/dL (4.5 mmol/L) elevated
>/=1000 mg/dL (11.3 mmol/L) very elevated

Additional Points
Current guidelines raises those with diabetes to an equivalent risk level for heart attack as those with coronary heart disease
Recommends treatment for beyond LDL lowering for those with TG >/= 200 mg/dL
Encourages use of plant stanols/sterols and viscous soluble fiber as a therapeutic dietary option

POSSIBLE NEW TESTS

Lipoprotein (a)
JAMA 1996;276:544-548
JAMA 1994;271:999-1003

Elevated levels associated with increased risk in many studies, but not all-independent from other lipoproteins

Composed of an LDL with an extra lipoprotein called apo(a) attached by a disulfide bond to apo B-100

Apo(a) is heterogenous in length because of a genetically variable repeating peptide sequence called kringles (MW varying from 185-650 kDa)

>75% homology to plasminogen suggesting that it interferes with plasminogen binding and disrupts the fibrinolytic cascade

Measurments are for apo(a) protein content which is then converted to total particle mass or for cholesterol concentration, similar to LDL or HDL

Assay uses the high degree of glycosylation by binding Lp(a) to lectin, eluting, then measuring cholesterol

Triglyceride rich lipoprotein remnants (TRL) Lipoproteins containing the greatest proportion of triglyceride including chylomicrons, chylomicron remnants, VLDL, VLDL remnants, and intermediate density lipoproteins (IDL)

Homocysteine
N Engl J Med 1998;338:1009-1015

Addition of folate reduced levels leading to decreased risk of CVD

C-reactive protein
N Engl J Med 2000;342:836-843

Ultrasensitive measurment has revealed a very small rise may indicate higher levels of risk for CVD

CLINICAL UTILITY CHARACTERIZATION

Veterans Affairs HDL Intervention Trial (VA-HIT) showed utility in raising HDL levels
N Engl J Med 1999;341:410-418
2500 men with coronary artery disease and relatively normal baseline levels of LDL, cholesterol, TG, but low HDL levels

Significant reduction in both primary and secondary endpoints in men with CAD when HDL was raised using gemfibrozil therpay

Raising HLD lowers risk without a change in LDL
7.5% increase in HDL and 24.5% decrease in TG associated with 22% decrease in coronary events and a 25% decrease in stroke

INTERFERING DISEASES OR SUBSTANCES THAT ELEVATE LEVELS CHARACTERIZATION

Posture Ideally, patient should be sitting for at least 20 minutes before sample is taken

Standing vs. lying down TC 10% higher
TG 12% higher
HDL 7% higher

INTERFERING DISEASES OR SUBSTANCES
THAT DECREASE LEVELS CHARACTERIZATION

Postprandial levels HDL may be slightly lower

Clinical Diagnosis and Management by Laboratory Methods. 20th Edition. Henry JB. WB Saunders 2001.

Commonly Used Terms

Atherosclerotic Disease

Heart

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Commonly Used Terms
This is a glossary of terms often found in a pathology report.

Diagnostic Process
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Surgical Pathology Report
Examine an actual biopsy report to understand what each section means

Special Stains
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Internet Links

Last Modified 1/14/2003

ANALYTICAL METHOD
LDL	Most methodes have derived this using the Friedewald formula wich depends upon the total cholesterol, HDL, and TG-use of this formula in postprandial samples may underestimate levels by as much as 20%-the reason is mobilization of cholesterol out of LDL and HDL and into chylomicrons and VLDL Direct measurement should be able to measure non fasting samples
BIOCHEMICAL THEORY	See below
IDEAL TESTING STATE	Nine hour fast but a 12-14 hour fast after a low-fat, low-calorie meal, with no intake of alcohol for 24 hours is preferable
REFERNCE RANGE	JAMA 2001;285:2486-2497 Current Recommendations for Adults from the National Cholesterol Education Program (NCEP) Third Report
*Total Cholesterol (TC)*	>240 mg/dL >6.2 mmol/L
*Low Density Lipoprotein (LDL-C)*	Optimal <100 mg/dL Near or above optimal (100-129 mg/dL) Borderline High (130-159 mg/dL) High (160-189 mg/dL) Very High (>/= 190 mg/dL)
*High Density Lipoprotein (HDL)*	>40 mg/dL
*Triglyceride (TG)*	>/=150 mg/dL borderline >/=400 mg/dL (4.5 mmol/L) elevated >/=1000 mg/dL (11.3 mmol/L) very elevated
Additional Points	Current guidelines raises those with diabetes to an equivalent risk level for heart attack as those with coronary heart disease Recommends treatment for beyond LDL lowering for those with TG >/= 200 mg/dL Encourages use of plant stanols/sterols and viscous soluble fiber as a therapeutic dietary option
POSSIBLE NEW TESTS
Lipoprotein (a)	JAMA 1996;276:544-548 JAMA 1994;271:999-1003 Elevated levels associated with increased risk in many studies, but not all-independent from other lipoproteins Composed of an LDL with an extra lipoprotein called apo(a) attached by a disulfide bond to apo B-100 Apo(a) is heterogenous in length because of a genetically variable repeating peptide sequence called kringles (MW varying from 185-650 kDa) >75% homology to plasminogen suggesting that it interferes with plasminogen binding and disrupts the fibrinolytic cascade Measurments are for apo(a) protein content which is then converted to total particle mass or for cholesterol concentration, similar to LDL or HDL Assay uses the high degree of glycosylation by binding Lp(a) to lectin, eluting, then measuring cholesterol
Triglyceride rich lipoprotein remnants (TRL)	Lipoproteins containing the greatest proportion of triglyceride including chylomicrons, chylomicron remnants, VLDL, VLDL remnants, and intermediate density lipoproteins (IDL)
Homocysteine	N Engl J Med 1998;338:1009-1015 Addition of folate reduced levels leading to decreased risk of CVD
C-reactive protein	N Engl J Med 2000;342:836-843 Ultrasensitive measurment has revealed a very small rise may indicate higher levels of risk for CVD

INTERFERING DISEASES OR SUBSTANCES THAT ELEVATE LEVELS	CHARACTERIZATION
Posture	Ideally, patient should be sitting for at least 20 minutes before sample is taken
Standing vs. lying down	TC 10% higher TG 12% higher HDL 7% higher

INTERFERING DISEASES OR SUBSTANCES THAT DECREASE LEVELS	CHARACTERIZATION
Postprandial levels	HDL may be slightly lower