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Direct LDL Cholesterol Blood Test

Last updated Aug. 24, 2015

Approved by: Maulik P. Purohit MD MPH

What are the other Names for this Test? (Equivalent Terms)

  • Direct Low-Density Lipoprotein Cholesterol Blood Test
  • Direct LDLC Blood Test
  • Direct LDL-C Blood Test 

What is Direct LDL Cholesterol Blood Test? (Background Information)

  • Low-density lipoprotein (LDL) is one of the several protein transporters of cholesterol, through blood. It is necessary for the regulation of fat metabolism
  • Lipoproteins are carriers of cholesterol and fats. They are essential because cholesterol and fats are insoluble in blood, and would otherwise coagulate and clog blood vessels
  • Lipoproteins contain apolipoproteins (“apo-“ means detached) as part of their structure. Apolipoproteins are required for transport and migration outside the blood vessel.
  • The type of apolipoprotein contained by a lipoprotein, determines where the lipoprotein will go. This is because, cells at the destination recognize lipoproteins by the apolipoproteins they contain
  • Lipoprotein is made up of a combination of fat and protein. There are different kinds of lipoproteins depending on the ratio of protein to fat. Very-low density lipoproteins (VLDL) and chylomicrons contain high amounts of fat to protein ratio. High-density lipoproteins contain less fat to protein ratio
  • Low-density lipoproteins (LDL) transport fat and cholesterol from the liver to the rest of the body. Thus, they are called “bad” cholesterol
  • High-density lipoproteins (HDL) transport fat and cholesterol from the body back to the liver for metabolism. Thus, they are called “good” cholesterol
  • The Direct LDL Cholesterol Blood Test is a test to assess the levels of LDL in circulation. It is used to estimate the risk for cardiovascular disease. It also provides a measure of cardiovascular health 

What are the Clinical Indications for performing the Direct LDL Cholesterol Blood Test?

Following are the clinical indications for performing the Direct LDL Cholesterol Blood Test:

  • Evaluating the risk for cardiovascular disease, which is marked by:
    • Chest pain or discomfort
    • Shortness of breath
    • Fatigue
    • Jaw pain
    • Family history of cardiovascular disease
  • Monitoring therapy for cardiovascular disease or high cholesterol levels 

How is the Specimen Collected for Direct LDL Cholesterol Blood Test?

Following is the specimen collection process for Direct LDL Cholesterol Blood Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test. 

What is the Significance of the  Direct LDL Cholesterol Blood Test Result?

The significance of Direct LDL Cholesterol Blood Test is explained:

  • High LDL cholesterol levels may indicate:
    • Corneal arcus
    • Hyperlipoproteinemia types II a and II b
    • Coronary artery disease (CAD)
    • Tendon and tuberous xanthomas
    • Anorexia
    • Kidney disorder
    • Liver disorder
    • Cushing’s syndrome
    • Diabetes
    • Hypothyroidism
    • Porphyria
    • Diet high in cholesterol and saturated fat
  • Low LDL cholesterol levels may indicate:
    • Tangier disease
    • Hyperlipoproteinemia and a-ß-lipoproteinemia
    • Chronic anemia
    • Lung disorder
    • Hyperthyroidism
    • Myeloma
    • Reye’s syndrome 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

Additional and Relevant Useful Information:

  • The Direct LDL Cholesterol Blood Test measures LDL levels directly. However, LDL levels can also be calculated indirectly through the use of a formula, which is LDL = (Total cholesterol) – (HDL) – (VLDL)
  • Certain factors may interfere with the results of this test. These include stress, pregnancy, and individual genetic predispositions to certain enzyme deficiencies 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis. 

What are some Useful Resources for Additional Information?

DoveMed is currently working to bring you additional resources.

Please sign up by creating a DoveMed account to receive periodic notification on information updates. 

References and Information Sources used for the Article:

Lab Tests Online (2014, January 27). Retrieved July 30, 2014 from http://labtestsonline.org/understanding/analytes/ldl/

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Nelson, D. L., Nelson, D. L., Lehninger, A. L., & Cox, M. M. (2008). Lehninger principles of biochemistry (5th ed.). New York, NY: W.H. Freeman.

Schnell, Z. B., Van, L. A., & Kranpitz, T. R. (2003). Davis's Comprehensive handbook of laboratory and diagnostic tests: With nursing implications. Philadelphia: F.A. Davis.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Aug. 3, 2014
Last updated: Aug. 24, 2015