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LDL Cholesterol, Serum/Plasma — Substance Concentration

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

This blood test measures low-density lipoprotein (LDL) cholesterol, a form of cholesterol that can build up in artery walls.

Quick summary

["LDL cholesterol helps assess cardiovascular risk and may be used to guide cholesterol-lowering treatment."]

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

Key facts at a glance

LOINC
91118-0
Short code
LDL7c SerPl-sCnc
Synonyms
LDL7c 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 test measures the amount of LDL, or “bad,” cholesterol in your blood. Higher levels over time can contribute to cholesterol buildup in arteries and increase the risk of heart attack and stroke.

Why might I need this test?

Your clinician may order this test as part of a heart-risk assessment, to monitor cholesterol treatment, or to evaluate an unusually high or low cholesterol result. It is often considered with HDL cholesterol, triglycerides, and your overall medical history.

How is the test performed?

A blood sample is drawn from a vein, usually from the arm. The laboratory measures LDL cholesterol using an approved biochemical method, and the result is reported with units and a reference range.

How do I prepare for the test?

Follow your clinician’s or laboratory’s instructions about fasting. If fasting is requested, it is commonly for 8 to 12 hours; water is usually allowed, and you should take medicines unless your clinician tells you otherwise. Avoid a high-fat meal before the test.

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 fasting required for an LDL cholesterol test?
Sometimes. Your clinician or laboratory may request 8 to 12 hours of fasting, although nonfasting LDL testing is also used in some care settings. Check the instructions provided with your test order.
Can I take my medicines before the test?
Usually, yes, but follow your clinician’s instructions. Taking cholesterol-lowering medicines or other medicines may affect the result, so tell the laboratory about anything you have taken.
Does a high LDL cholesterol level mean I have heart disease?
No. A high result is a risk factor, not a diagnosis of heart disease. Your clinician will consider the result along with blood pressure, diabetes, smoking, family history, and other cholesterol measurements.
  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