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LDL Cholesterol, Serum/Plasma

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

Measures low-density lipoprotein (LDL) cholesterol in blood. LDL is commonly called “bad” cholesterol because higher levels are associated with buildup of fatty plaque in arteries.

Quick summary

["This blood test helps assess cardiovascular risk by measuring LDL (“bad”) cholesterol."]

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

Key facts at a glance

LOINC
13459-3
Short code
LDLc SerPl
Synonyms
LDLc 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 serum or plasma, the liquid part of blood. LDL is a type of cholesterol that can contribute to fatty plaque buildup in artery walls.

Why might I need this test?

Your clinician may order this test to evaluate your risk of heart attack and stroke, investigate unusually high or low cholesterol, assess a possible inherited cholesterol condition, or monitor cholesterol treatment or lifestyle changes.

How is the test performed?

A blood sample is drawn from a vein and analyzed in a laboratory. Depending on the laboratory and test order, LDL cholesterol may be measured directly or calculated from the results of other cholesterol measurements.

How do I prepare for the test?

Some clinicians request fasting for cholesterol testing, often for about 9–12 hours. Follow your clinician’s or laboratory’s instructions, and if fasting is not required, avoid eating a large, high-fat meal shortly before the test if possible. You may usually drink water.

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 cholesterol buildup in arteries. The term describes its association with cardiovascular risk rather than the test itself.
Does LDL cholesterol require fasting?
Fasting may be requested for some cholesterol tests, but the requirement depends on your clinician and laboratory. If you are unsure, ask whether you should avoid food for 9–12 hours before the test.
What if my LDL cholesterol is high?
High LDL cholesterol does not always mean you have heart disease, but it may indicate increased cardiovascular risk. Your clinician can discuss your overall risk, lifestyle measures, and whether medication or further testing is appropriate.
  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