Test Details
Methodology
Enzymatic/spectrophotometric without sample pretreatment
Result Turnaround Time
Within 1 day
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
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.2 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.3
Limitations
NCEP guidelines for interpretation (see Reference Interval) 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.
Footnotes
Specimen Requirements
Specimen
Serum (preferred) or plasma
Volume
1 mL
Minimum Volume
0.7 mL (Note: This volume does not allow for repeat testing.)
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.
Collection Instructions
Separate serum or plasma from cells within 45 minutes of collection.
Stability Requirements
Temperature | Period |
|---|---|
Room temperature | 14 days |
Refrigerated | 14 days |
Frozen | 14 days |
Freeze/thaw cycles | Stable x3 |
Reference Range
See table.
Age | Male | Female |
|---|---|---|
0-19 y | 0-109 | 0-109 |
>19 y | 0-99 | 0-99 |
Storage Instructions
Room temperature
Patient Preparation
Patients are not required to fast prior to blood collection. Nonfasting and fasting samples can be used. Nonfasting results are slightly lower than fasting results.
Causes for Rejection
Use of anticoagulants containing citrate
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 120295 | LDL Cholesterol (Direct) | 18262-6 | 120297 | LDL Chol. (Direct) | mg/dL | 18262-6 |
| 120295 | LDL Cholesterol (Direct) | 18262-6 | 011924 | LDL Direct Comment: | N/A | |
| Order Code | 120295 | |||||
| Order Code Name | LDL Cholesterol (Direct) | |||||
| Order Loinc | 18262-6 | |||||
| Result Code | 120297 | |||||
| Result Code Name | LDL Chol. (Direct) | |||||
| UofM | mg/dL | |||||
| Result LOINC | 18262-6 | |||||
| Order Code | 120295 | |||||
| Order Code Name | LDL Cholesterol (Direct) | |||||
| Order Loinc | 18262-6 | |||||
| Result Code | 011924 | |||||
| Result Code Name | LDL Direct Comment: | |||||
| UofM | ||||||
| Result LOINC | N/A |