Synonyms

   Low-density lipoprotein cholesterol

Clinical Significance

   The purpose of a direct LDL cholesterol test is to determine the amount of “bad” LDL cholesterol in the blood. Assessing LDL cholesterol levels can be involved in health screening, monitoring, and diagnosis.

   Screening is looking for evidence of health problems before any symptoms are present. Evaluating LDL cholesterol levels can play an important role in screening for cardiovascular disease risk. Early detection of high levels of LDL cholesterol can help identify people who are more likely to develop heart disease or experience a heart attack or stroke.

   Monitoring is checking how a condition progresses over time. LDL cholesterol may be tested periodically to assess cardiovascular health. LDL cholesterol testing can also be used to see if treatment to lower LDL cholesterol has been effective.

   Diagnosis is the process of identifying the cause of health problems after symptoms have started. A direct LDL cholesterol test may be part of the diagnostic process for cardiovascular problems. Cholesterol levels may also be tested for certain conditions that affect the pancreas, liver, and thyroid.

   High triglycerides can invalidate the formula used to calculate LDL cholesterol. As a result, the doctor may recommend a direct LDL cholesterol test if you had high levels of triglycerides on a prior test or if you have risk factors for high triglycerides.

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days

   Frozen : 30 days

Reference Range

   < 130 mg/dL

Interpretation

   In general, it is desirable to have LDL cholesterol levels below 100 mg/dL. High levels of LDL cholesterol can lead to a condition called arteriosclerosis. Arteriosclerosis is an accumulation of plaque in the arteries and can contribute to cardiovascular diseases like coronary heart disease, heart attack, and stroke.

   Careful interpretation of a direct LDL cholesterol test by your doctor is especially important because standard guidelines about managing high cholesterol levels are based on studies that used calculated LDL cholesterol. Low-density lipoprotein cholesterol results of 190 mg/dL or above in adults (> or =160 mg/dL in children) are severely elevated and may indicate familial hypercholesterolemia.