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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 cholesterol levels and cardiovascular risk.

Quick summary

["LDL cholesterol helps determine how much cholesterol may build up in artery walls over time."]

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

Key facts at a glance

LOINC
91115-6
Short code
LDL4c SerPl-sCnc
Synonyms
LDL4c 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, often called “bad” cholesterol. It is commonly included in a lipid panel or cholesterol screening.

Why might I need this test?

Your clinician may order this test to evaluate your cardiovascular risk, especially if you have high cholesterol, heart disease, diabetes, high blood pressure, or a family history of these conditions.

How is the test performed?

A blood sample is collected from a vein and analyzed in a laboratory to determine the amount of LDL cholesterol in the blood.

How do I prepare for the test?

Fasting is usually not required for routine LDL testing, but your clinician may request it, particularly when other lipid measurements are being checked. Follow the instructions provided, drink water if you are asked to fast, and do not stop prescribed medicines unless instructed.

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

Why is LDL cholesterol called “bad” cholesterol?
LDL carries cholesterol in the blood and can contribute to cholesterol buildup in artery walls. Higher levels are generally associated with greater cardiovascular risk.
Do I need to fast before this test?
Fasting is often unnecessary, but it may be recommended when LDL is being checked as part of a complete lipid panel. Follow your clinician’s or laboratory’s specific instructions.
Can medicines or other conditions affect the result?
Yes. Cholesterol-lowering medicines, recent weight changes, fasting, and certain medical conditions can influence LDL cholesterol levels. Tell your clinician about relevant medicines and health history.
  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