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LDL Cholesterol, Serum/Plasma

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

An LDL cholesterol test measures the amount of “bad” cholesterol in blood and may be used to help assess cardiovascular risk.

Quick summary

["LDL cholesterol helps assess the buildup of fatty plaques in artery walls and your risk of heart disease and stroke."]

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

Key facts at a glance

LOINC
14155-6
Short code
LDLc Prctl SerPl
Synonyms
LDLc Prctl 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 LDL cholesterol in a blood sample. LDL is often called “bad” cholesterol because high levels can contribute to fatty plaque buildup in arteries.

Why might I need this test?

Your clinician may order this test as part of a cholesterol screening or follow-up, especially if you have risk factors for heart disease, stroke, or another condition affected by cholesterol.

How is the test performed?

A small blood sample is collected, usually from a vein, and analyzed by a laboratory. Depending on the laboratory, LDL cholesterol may be measured directly or calculated using other cholesterol measurements.

How do I prepare for the test?

Fasting may be requested, although many laboratories can interpret a nonfasting LDL result. Follow your clinician’s instructions and tell the laboratory if you are pregnant, have had a recent heart attack, or have another recent illness.

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 this the same as total cholesterol?
No. Total cholesterol includes several types of cholesterol, while this test focuses on LDL, the form most closely associated with arterial plaque buildup.
Do I need to fast before this test?
Sometimes. Your clinician or laboratory may request fasting, especially when other lipid measurements are being interpreted, but a nonfasting result can still be useful.
How often should LDL cholesterol be checked?
The frequency depends on your age, medical history, medications, and cardiovascular risk. Your clinician can recommend a schedule based on your overall health.
  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