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Low-Density Lipoprotein (LDL) Cholesterol, Serum or Plasma Concentration

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
43727-7
Short code
LDL Small SerPl-sCnc
Synonyms
LDL Small SerPl-sCnc
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 This Test Matters

LDL cholesterol is one of the main components of your total cholesterol profile. While HDL cholesterol (often called 'good cholesterol') helps remove LDL from your arteries, high LDL levels can contribute to plaque buildup, which may restrict blood flow and increase the risk of heart attack or stroke. Regular monitoring helps manage your cardiovascular health.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood sample drawn from a vein in your arm, typically after fasting for 9–12 hours (though some labs may offer non-fasting options). If you’re unsure about fasting, ask your healthcare provider.

How the Test Works

Blood is collected and analyzed to measure LDL cholesterol levels. The test may use methods like enzymatic assays or immunoassays to detect and quantify LDL particles in your serum or plasma.

What the Results Mean

Results are reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While specific ranges vary by lab, higher-than-normal levels may signal increased cardiovascular risk, prompting further evaluation or lifestyle adjustments.

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.

Clinical Significance

Short name

LDL Cholesterol

Frequently asked questions

What does a high LDL cholesterol level indicate?
High LDL cholesterol is a major risk factor for atherosclerosis, where plaque builds up in arteries. Over time, this can lead to narrowed or blocked arteries, increasing the risk of heart disease, stroke, or peripheral artery disease. Your healthcare provider may recommend lifestyle changes, medications, or other tests to assess risk.
What does a low LDL cholesterol level suggest?
Low LDL cholesterol may indicate good cardiovascular health, but it doesn’t replace other risk factors like smoking, diabetes, or family history. Always discuss results with your provider to understand your overall risk profile.
Can LDL cholesterol be lowered naturally?
Yes! Dietary changes (e.g., reducing saturated fats, increasing fiber), regular exercise, and maintaining a healthy weight can help lower LDL cholesterol. Some medications, like statins, may also be prescribed if lifestyle changes aren’t sufficient.
  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