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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 cardiovascular risk and guide cholesterol-lowering treatment.

Quick summary

["Higher LDL cholesterol can increase the risk of heart attack and stroke."]

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

Key facts at a glance

LOINC
91117-2
Short code
LDL6c SerPl-sCnc
Synonyms
LDL6c 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 cholesterol, often called “bad” cholesterol. LDL helps transport cholesterol through the bloodstream, and its concentration is used to help estimate cardiovascular risk.

Why might I need this test?

Your clinician may order this test as part of a cholesterol screening or follow-up, particularly if you have heart disease, diabetes, high blood pressure, or other risk factors for heart attack and stroke. It may also be used to monitor the effectiveness of lifestyle changes or cholesterol-lowering treatment.

How is the test performed?

A blood sample is collected, and the laboratory measures LDL cholesterol in serum or plasma. Some results are calculated using other cholesterol measurements, while others are measured directly.

How do I prepare for the test?

Follow your clinician’s instructions about fasting. Some lipid tests are performed without fasting, while others may require you to avoid food for several hours. Drinking water is generally acceptable unless your clinician gives different instructions.

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 result always dangerous?
No. Risk is assessed using the LDL level together with blood pressure, diabetes, smoking, family history, and other factors. A clinician can put your result into the context of your overall cardiovascular risk.
Do I need to fast before this test?
It depends on the laboratory and the reason for the test. Some lipid panels can be performed without fasting, but your clinician or laboratory should provide specific preparation instructions.
Can diet and exercise lower LDL cholesterol?
For many people, a heart-healthy eating pattern, regular physical activity, and stopping smoking can improve cholesterol levels. Some people also need medication prescribed by their clinician.
  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