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Low-Density Lipoprotein (LDL) Cholesterol

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

A blood test that measures LDL (“bad”) cholesterol, a lipoprotein associated with fatty plaque buildup in the arteries and increased cardiovascular risk.

Quick summary

["LDL cholesterol helps assess the buildup of fatty plaque in your arteries and your risk of heart attack or stroke."]

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

Key facts at a glance

LOINC
75861-5
Short code
HEDIS 2015-20 LDL-C
Synonyms
HEDIS 2015-20 LDL-C
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 low-density lipoprotein cholesterol in your blood. LDL cholesterol carries cholesterol through the bloodstream and can contribute to fatty plaque buildup in artery walls.

Why might I need this test?

Your clinician may order this test to assess your risk of heart disease and stroke, evaluate a high cholesterol level, or monitor treatment for high LDL cholesterol. It is often part of a broader lipid panel that also measures total cholesterol, HDL cholesterol, and triglycerides.

How is the test performed?

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

How do I prepare for the test?

You may be able to have this test without fasting, but follow your clinician’s instructions because fasting may be requested in some situations. Tell the laboratory if you are pregnant or have had a recent heart attack, stroke, or other major illness, as these factors can temporarily affect cholesterol results.

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

Do I need to fast before an LDL cholesterol test?
Fasting is not always required, but your clinician may request it. If you have been asked to fast, avoid food and beverages other than water for the period specified by the laboratory.
Why is LDL cholesterol called “bad” cholesterol?
LDL carries cholesterol through the blood and can allow it to collect in artery walls. This plaque buildup can narrow or harden arteries and increase the risk of heart attack and stroke.
How is LDL cholesterol different from HDL cholesterol?
LDL moves cholesterol from the liver into the arteries, while HDL helps transport cholesterol away from the arteries back toward the liver. Both are measured as part of a typical lipid panel.
  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