Lipoprotein Subfraction Profile Testing
These are tests to help evaluate your risk of developing coronary artery disease (CAD).
Lipoprotein subfraction tests separate two of the commonly measured lipoprotein fractions – HDL (the carrier of good cholesterol) and LDL (the carrier of bad cholesterol) – into subfractions based on their size, density, and/or electrical charge.
Lipoproteins are particles containing parts of proteins, cholesterol, triglycerides, and phospholipids. Studies have shown that small dense LDL particles are more likely to cause atherosclerosis (hardening of the arteries) than light fluffy LDL particles.
The number of small dense LDL and HDL particles a person has is partially genetically determined, partially due to gender (males tend to have more small LDL and HDL than females), and partially due to lifestyle and a person's general state of health. Certain diseases and conditions, such as diabetes and hypertension, are associated with increased levels of small dense LDL.
PREPARATION FOR TEST
A blood sample is obtained by inserting a needle into a vein in the arm.
Male: Greater than 45 mg/dL or Greater than 0.75 mmol/L (SI units)
Female: Greater than 55 mg/dL or Greater than 0.91 mmol/L (SI units)
Risk of Heart Disease
Low: 60 (1.55) HDL mg/dL (SI Units)
Moderate: 45 (1.17) HDL mg/dL (SI Units)
High: 25 (0.65) HDL mg/dL (SI Units)
Low: 70 (1.81) HDL mg/dL (SI Units)
Moderate: 55 (1.42) HDL mg/dL (SI Units)
High: 35 (0.90) HDL mg/dL (SI Units)
LDL: 60-180 mg/dL or Less than 3.37 mmol/L (SI units)
VLDL: 7-32 mg/dL
Normal values depend on many factors. Your lab will provide a range of normal values with your test results.
MEANING OF TEST
Your caregiver will go over your test results with you and discuss the importance of this test. Reference values are dependent on many factors, including patient age, gender, sample population, and testing method. Numeric test results have different meanings in different labs. Your lab report should include the specific reference range for your test.
In general, the result is interpreted within the framework of a lipid profile and its associated risk. If the patient has primarily small dense LDL, this finding will add to the risk of developing CAD above and beyond the risk associated with the total LDL. On the other hand, the presence of exclusively large fluffy LDL will add no additional risk. The picture is more complex with HDL subfractions and there is no consensus on how to include the findings in risk assessment, but in general the presence of large fluffy HDL is thought to offer more protection than small dense HDL.
It is important to remember that lipoprotein subfraction testing (and other lipid and cardiac risk factor testing) is not diagnostic. It attempts to evaluate a patient's statistical risk of developing CAD but it cannot predict the development or severity of CAD in a particular patient.
Results of lipoprotein subfraction testing reflect the method and reporting format used as well as the patient's total LDL-cholesterol and/or HDL-cholesterol. Since different methods separate the subclasses based on different physical properties (size, density, and/or electrical charge), results may not be directly comparable method to method or laboratory to laboratory.
OBTAINING THE TEST RESULTS
Make sure you receive the results of your test. Ask as to how these results are to be obtained if you have not been informed. It is your responsibility to obtain your test results.
Your caregiver will provide further instructions or treatment options if necessary.