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LDL Cholesterol, Serum/Plasma — Mass Concentration

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

This blood test measures LDL (“bad”) cholesterol, a lipoprotein that carries cholesterol in the blood and can contribute to fatty buildup in arteries.

Quick summary

["LDL cholesterol is commonly used to help assess cardiovascular risk and monitor cholesterol-lowering treatment."]

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

Key facts at a glance

LOINC
108018-3
Short code
LDLc Msmt SerPl
Synonyms
LDLc Msmt SerPl
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 test measures the amount of LDL cholesterol in a blood sample. LDL is often called “bad” cholesterol because high levels can promote cholesterol deposits in artery walls.

Why might I need this test?

A clinician may order this test to assess cardiovascular risk, evaluate unusually high or low cholesterol levels, or monitor the effectiveness of diet changes and cholesterol-lowering medicines.

How is the test performed?

Blood is drawn from a vein and analyzed in the laboratory. LDL cholesterol may be measured directly or calculated from other lipid measurements, depending on the laboratory method.

How do I prepare for the test?

Follow any fasting instructions provided by your clinician. Some LDL tests can be performed without fasting, but fasting may be requested when other cholesterol measurements are needed or when a standard lipid panel is ordered.

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 a higher LDL cholesterol level always harmful?
No. LDL must be interpreted in context, including age, family history, blood pressure, diabetes, smoking, and other risk factors. Even a modest value may be important in a person with substantial cardiovascular risk.
Does this test require fasting?
It depends on the laboratory method and the other tests ordered with it. Ask your clinician whether you should fast and for how long before the blood draw.
Can I lower LDL cholesterol without medication?
Some people can reduce LDL through a heart-healthy diet, regular physical activity, weight management, and stopping tobacco use. A clinician can determine whether medication is also needed based on the result and overall cardiovascular risk.
  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