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

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

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

Quick summary

["LDL cholesterol is a key marker of cardiovascular risk, with higher levels generally associated with greater risk."]

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

Key facts at a glance

LOINC
56137-3
Short code
LDL2 SerPl-sCnc
Synonyms
LDL2 SerPl-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
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 blood test measures low-density lipoprotein (LDL) cholesterol, a form of cholesterol that circulates in the blood. It is commonly used to evaluate cardiovascular risk and monitor treatment for high cholesterol.

Why might I need this test?

Your clinician may order this test as part of a cholesterol screening or lipid panel, particularly if you have risk factors for heart disease or stroke. It may also be used to assess the effectiveness of diet, exercise, or cholesterol-lowering medication.

How is the test performed?

A blood sample is drawn from a vein and analyzed in a laboratory to determine the concentration of LDL cholesterol. The result is often interpreted along with total cholesterol, HDL cholesterol, triglycerides, and your personal cardiovascular risk factors.

How do I prepare for the test?

Follow your clinician’s instructions about fasting. Some lipid tests are more accurate after fasting, while others may not require it. Tell your clinician if you are taking cholesterol-lowering medication, because this can affect the result.

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

LDL Cholesterol

Frequently asked questions

Is LDL cholesterol the same as “bad” cholesterol?
Yes. LDL is often called “bad” cholesterol because it can contribute to the buildup of fatty plaque in arteries.
Does this test require fasting?
It depends on the laboratory and the test ordered. Your clinician or testing center should provide specific fasting instructions before the blood draw.
Can I lower LDL cholesterol without medication?
Healthy eating, regular physical activity, maintaining a healthy weight, and not smoking may help improve cholesterol. Your clinician can advise whether medication is also needed.
  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