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Low-Density Lipoprotein Cholesterol, Serum/Plasma — Direct Assay, Substance Concentration

Published: August 9, 2026Updated: August 16, 2026

Measures LDL (“bad”) cholesterol directly in blood to help assess cardiovascular risk and guide cholesterol-lowering treatment.

Quick summary

["A direct blood test measuring LDL cholesterol, a factor associated with buildup of fatty plaque in arteries."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
69419-0
Short code
LDLc SerPl Direct Assay-sCnc
Synonyms
LDLc SerPl Direct Assay-sCnc
Category
lipid
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
100
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
direct-assay
CPT
83721
SNOMED
113079007
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

This test measures the concentration of low-density lipoprotein cholesterol (LDL-C) in serum or plasma. LDL-C is often called “bad” cholesterol because elevated levels can contribute to fatty plaque buildup in arteries.

Why might I need this test?

Your clinician may order this test to evaluate your risk of heart attack and stroke, diagnose or monitor high cholesterol, or assess the effectiveness of cholesterol-lowering treatment. A direct measurement may also be used when another way of calculating LDL-C is not appropriate.

How is the test performed?

A blood sample is collected, and the laboratory uses a direct assay to measure LDL cholesterol rather than calculating it from other cholesterol values. The sample is usually taken from a vein and analyzed in the laboratory.

How do I prepare for the test?

Follow your clinician’s instructions about fasting. Some laboratories request fasting for lipid testing, while others do not. Tell the laboratory if you are pregnant, have recently given blood, or are taking cholesterol-lowering medicines, as these factors may affect interpretation.

Reference range

Optimal: <100 mg/dLN/A

Specimen: serum

Fasting for 12-14 hours preferred. Water is permitted. Avoid alcohol for 24 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Direct LDL Cholesterol

Frequently asked questions

Is this the same as a standard lipid panel?
A standard lipid panel may calculate LDL-C from other values, whereas this test measures LDL-C directly. Your clinician can explain why a direct assay was selected.
Do I need to fast before this test?
Fasting requirements vary by laboratory and clinical situation. Follow the instructions provided by your clinician or laboratory, and ask if you are unsure.
Does a low LDL-C result mean I cannot develop heart disease?
No. LDL-C is only one part of cardiovascular risk assessment, and other factors such as blood pressure, diabetes, smoking, family history, and HDL cholesterol also matter.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy