Description
Synonyms:
Direct LDL
Direct LDLC
LDL Cholesterol, Direct
LDL, Direct
LDLC, Direct
Use: For the direct determination of LDL cholesterol in nonfasting patients or in patients whose fasting triglycerides are >400 mg/dL, where the estimation of LDL by calculation may not be possible or may lead to inaccuracies. LDL cholesterol measurement, in conjunction with other lipid measurements, has been shown to be useful in assessing the risk of coronary heart disease (CHD). The National Cholesterol Education Program (NCEP)1 has stated that LDL cholesterol should be the "key index" in determination of CHD risk. Laboratory estimation of LDL cholesterol is most commonly determined by the use of formulas, such as the Friedewald formula. Use of this formula is limited to fasting samples with triglycerides <400 mg/dL. Triglyceride values between 250-400 mg/dL may also be associated with errors in LDL cholesterol estimation by calculation which, in turn, can lead to misclassification of the patient in regard to the NCEP guidelines.
Limitations: NCEP guidelines for interpretation (see Reference Intervals) are based on serum values, and when classifying patients, serum or serum equivalent values should be used. For this direct LDL method, a factor of 1.06 should be used to convert EDTA plasma values to serum values. There is no significant interference from hemolysis up to 10.0 g/L hemoglobin, from bilirubin up to 30 mg/dL, and from triglycerides up to 1200 mg/dL. Abnormal liver function affects lipid metabolism; consequently, HDL and LDL results may be of limited diagnostic value in patients with hepatic disorders.
Reference Interval: National Cholesterol Education Program (NCEP) levels in terms of risk for coronary heart disease (based on serum values):
• Optimal: <100 mg/dL
• Near optimal/above optimal: <130 mg/dL
• Borderline high: 130-159 mg/dL
• High: 160-189 mg/dL
• Very high: >189 mg/dL