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Low-Density Lipoprotein (LDL) Cholesterol (Direct)

LDL Cholesterol, Direct Measurement, LDL Direct, Low Density Lipoprotein Cholesterol, Direct

Test Codes

EPIC: LAB102, Beaker: DLDL, Antrim 19313

Department

Chemistry

Instructions

It is preferred that the patient fast for 9-12 hours prior to specimen collection, but it is not required.

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)
Contact the Laboratory for acceptability of other tube types.

Physician Office/Draw Specimen Preparation

Let SST specimens clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged SST tube within two hours of collection.

Preparation for Courier Transport

Transport: Centrifuged SST tube refrigerated (2-8°C or 36-46°F). (Minimum: 0.5 mL)

Rejection Criteria

• Moderate to grossly hemolyzed specimens.
• Red-top tubes with serum not separated from cells within two hours of collection.

In-Lab Processing

Let SST specimens clot 30-60 minutes. Centrifuge SST tubes or Microtainers^® to separate serum from cells. Deliver immediately to the appropriate testing station.

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gel
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gel
Room Temperature (20-25°C or 68-77°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2-4 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 7 days

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Dearborn Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory

Performed

Monday – Sunday.
Results available within 24 hours of testing.

Reference Range

Age 0-19: 50 - 109 mg/dL.
Age 20 or Older: 50 - 129 mg/dL.

LDL Cholesterol Reference Range
Less than 70 mg/dL:	Optimal for a very high-risk person.
Less than 100 mg/dL:	Optimal for a high-risk person.
50-129 mg/dL:	Near or above optimal.
130-159 mg/dL:	Borderline high.
160-190 mg/dL:	High.
Greater than 190 mg/dL:	Very high.

NOTE: The appropriate LDL cholesterol level for an individual depends on overall risk factors for cardiovascular disease. According to ATP III guidelines risk factors are ASCVD (coronary heart disease, symptomatic carotid artery disease, peripheral arterial disease, abdominal aortic aneurysm), diabetes mellitus, cigarette smoking, hypertension, low HDL cholesterol (less than 40 mg/dL), family history of premature CHD and age (males 45 years or older, females 55 years or older). An HDL cholesterol 60 mg/dL or greater is regarded as a negative risk factor.

Test Methodology

Detergent Solubilization/Enzymatic.

Interpretation

• Low Density Lipoproteins (LDL) are a major factor in causing and influencing the progression of atherosclerosis. The LDL cholesterol value is an important clinical indicator in the risk assessment for coronary atherosclerosis.
• Elevated levels of LDL cholesterol are seen in primary hyperlipoproteinemias such as familial hypercholesterolemia, familial combined hyperlipidemia and polygenic hypercholesterolemia. Secondary elevations can result from hypothyroidism, nephrotic syndrome, dysglobulinemias, cholestatic liver disease, porphyria, pregnancy, diabetes, chronic renal failure or Cushing's syndrome.

Clinical Utility

This direct quantitative determination of LDL cholesterol aids in the diagnosis and management of coronary atherosclerosis.

Several organizations have issued guidelines for management of dyslipidemias, all aiming to standardize and optimize patient care. The recent ACC/AHA guidelines aim to reduce/prevent heart disease, peripheral vascular disease and stroke by taking into account lifestyle and lipid levels (1). Based on this information an estimate of ASCVD risk can be calculated and a decision on whether or not to treat (e.g. with statins) and modify lifestyle can be made. The ACC/AHA guidelines do not recommend specific cholesterol set points but aim for a particular percent decrease in LDL cholesterol. Our lab will continue to use the ATP guideline cut points in lipid reporting (2). The National Lipid Association also has recommendations that are similar to the ATP III guidelines (3).

Reference

1. Stone NJ, Robinson JG, Lichetenstein AH et al: ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014 63:2889-2934.
2. Third report of the National Cholesterol Education Program (NCEP) Expert Panel on detection, evaluation and treatment of high blood cholesterol in adults (ATP III). Circulation 2002;106:3143-3421.
3. Jacobson TA, Ito MK, Maki KC et al. National Lipid Association recommendations for patient-centered management of dyslipidemia. Part 1 – executive summary. J Clin Lipidol 2014;8:473-488.

CPT Codes

83721
LOINC: 18262-6

Contacts

Last Updated

11/4/2024