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Low-Density Lipoprotein Cholesterol (LDL-C) in Serum

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

This test measures the amount of LDL cholesterol in your blood, a key type of fat that can build up in your arteries over time.

Quick summary

["LDL cholesterol is often called 'bad cholesterol' because high levels may increase your risk of heart disease."]

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

Key facts at a glance

LOINC
2574-2
Short code
LDL SerPl-mCnc
Synonyms
LDL SerPl-mCnc
Category
chemistry
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

Why Is This Test Done?

Your doctor may order this test to assess your risk of heart disease, stroke, or other cardiovascular conditions. It helps monitor cholesterol levels, especially if you have a family history of high cholesterol or heart problems, or if you’re taking medications to manage cholesterol.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 9–12 hours before the test if your lab uses a specific method. Bring any medications you’re currently taking, as some (like cholesterol-lowering drugs) can affect results.

How the Test Works

A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum (the liquid part after clotting), and the LDL cholesterol level is measured using an automated immunoassay or enzymatic method to detect and quantify the fat.

What the Results Mean

Results are reported in milligrams per deciliter (mg/dL). While specific ranges vary by lab, higher LDL levels may indicate increased artery plaque risk, prompting lifestyle or medical interventions.

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

What causes LDL cholesterol levels to rise?
Several factors can contribute to elevated LDL cholesterol, including poor diet (high in saturated or trans fats), lack of physical activity, obesity, smoking, genetics, and certain medical conditions like diabetes or hypothyroidism. Lifestyle changes, medications, or both may be recommended to lower levels.
How often should I get this test?
The frequency depends on your health status. Typically, adults with no known risk factors may get tested every 4–5 years. Those with risk factors (e.g., high blood pressure, diabetes, or a family history of heart disease) may need testing more often, often every 1–2 years, as advised by your doctor.
Can diet or exercise affect LDL cholesterol results?
Yes. Dietary changes—such as reducing saturated fats, trans fats, and cholesterol-rich foods—along with regular physical activity can significantly lower LDL cholesterol. Exercise also helps improve overall heart health, though results may take weeks or months to reflect changes in lab tests.
  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