Direct LDL cholesterol (LDL, LDL cholesterol) is a chemistry test that reports LDL-C on a serum specimen. It is a stand-alone order, separate from the lipid panel. Consider it when you want an LDL value that does not depend on a calculation.
At a glance
| Detail | Information |
|---|---|
| Test name | Cholesterol Direct, LDL (aliases: LDL, LDL cholesterol) |
| Category | Chemistry |
| Order code | LDL |
| Specimen | Blood (SST) |
| Turnaround | 24-48 hours from receipt of sample |
| Ordered by | Requesting physician |
What it detects
| Group | Analyte |
|---|---|
| Lipid | LDL Cholesterol |
Related lipid tests on the same requisition:
- Cholesterol Direct, HDL
- Total cholesterol
- Triglycerides
- Apolipoprotein A-1
- Apolipoprotein B
- Lipid Panel: cholesterol, triglycerides, HDL, LDL, VLDL and Chol/HDL ratio
When to order it
- You want measured LDL-C, not a derived value. Our lipid panel report shows calculated LDL based on the Martin-Hopkins method. That method uses an adjustable triglyceride:VLDL cholesterol ratio, which varies with measured triglyceride and non-HDL cholesterol concentrations. The report note states that calculated LDL runs higher in specimens with higher triglycerides or lower non-HDL cholesterol.
- Triglycerides or non-HDL cholesterol sit at the extremes. Those are the specimens where the calculated value shifts most. A direct LDL order removes that variable.
- You are following LDL-C over time and want a single stand-alone result on the requisition.
For the broader lipid picture, pair it with HDL, total cholesterol and triglycerides, or order the Lipid Panel.
Specimen collection
- Container: SST (serum separator tube).
- Order of draw: 3rd, after blue/coag and after blood culture. The CLSI-recommended sequence is sterile (blood culture), citrate (light blue), serum (red/SST), heparin (green), EDTA (lavender), oxalate (gray).
- Handling:
- Invert the tube 5 to 10 times. Do not shake it, because shaking causes hemolysis.
- Let the tube clot upright for 30 minutes before centrifuging. Spinning early can cause fibrin strands and inaccurate results.
- Do not freeze an SST with the gel still in it. Pour the serum into an aliquot tube first.
- Do not pour blood from one tube into another.
- Labeling: Label at the bedside after collection, never before the draw. Verify two identifiers (full name and date of birth) on every tube.
- Volume, fasting and stability for this specific test: not specified in our documents. Check the order or call the lab at 248.800.6626 before you draw.
Understanding the report
Results are reported in mg/dL with a reference range and an H flag for values outside range, in a layout that separates within-range from outside-range results. On a lipid panel report, LDL appears alongside total cholesterol, triglycerides, HDL and the LDL/HDL risk ratio. The lab’s sample report shows a calculated LDL line with the Martin-Hopkins note attached. Reference ranges on your report are those printed by the lab for that result.
Why order it from Total Lab Solutions
- Defined turnaround. Results are reported 24-48 hours from the time we receive the sample.
- One requisition, one tube type. LDL, HDL, total cholesterol, triglycerides, Apo A-1, Apo B and the Lipid Panel are all SST tests on the same requisition. See the full testing panel.
- CLIA-certified, CAP-accredited facility at 1250 Stephenson Hwy, Suite 200, Troy, MI, running routine and specialized blood work under one roof.
- A lab you can call. Questions about a collection step or a specimen go to 248.800.6626, before the draw rather than after a rejection.
Frequently asked questions
When should a clinician order a direct LDL cholesterol instead of a calculated LDL?
Order it when you want LDL-C as a measured result. Our Martin-Hopkins note explains that calculated LDL depends on a triglyceride:VLDL ratio that varies with triglyceride and non-HDL cholesterol concentrations. Calculated values run higher in higher-triglyceride or lower-non-HDL specimens. Direct LDL is a stand-alone order (code LDL).
Does the direct LDL cholesterol test require fasting?
Our documents do not state a fasting requirement for this test. Check the order, or call the lab at 248.800.6626 to confirm before collection.
How does direct LDL-C compare with Friedewald or Martin-Hopkins calculated LDL at high triglyceride levels?
We do not publish a Friedewald comparison. For Martin-Hopkins, our report note states the calculation uses an adjustable triglyceride:VLDL cholesterol ratio that varies by measured triglyceride and non-HDL cholesterol, with increased calculated LDL seen in higher-triglyceride or lower-non-HDL specimens. For the lab’s full notice, see the Calculated LDL client announcement referenced on the report. For case-specific questions, contact the lab.
What is the typical turnaround time and specimen requirement for direct LDL cholesterol?
Turnaround is 24-48 hours from receipt of the sample. The specimen is blood collected in an SST.
Which CPT code and ICD-10 diagnosis codes are commonly used when billing a direct LDL cholesterol test?
We have not published a CPT code or ICD-10 codes for this test, so we will not suggest any here. Contact the lab at 248.800.6626 for billing questions.
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