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Skip This Step When Checking Lipid Levels

Although most guidelines recommend that patients fast before lipid testing, a recent study found no difference between fasting and nonfasting testing for predicting mortality.

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PRACTICE CHANGER
Stop requiring your patients to fast before undergoing lipid testing. Nonfasting total cholesterol (TC), HDL cholesterol, and LDL cholesterol levels are equally predictive of cardiovascular mortality and all-cause mortality.1

STRENGTH OF RECOMMENDATION
B: Based on a large, cross-sectional cohort study of adults followed for a mean of 14 years with patient-oriented outcomes.1

ILLUSTRATIVE CASE
A 57-year-old man with diabetes refuses to fast before coming to the clinic for lipid testing because he’s afraid he’ll become hypoglycemic. You have not been able to obtain a lipid panel on him for more than a year, and you want to determine his LDL level. Will a nonfasting lipid panel be useful?

Approximately 71 million adults in the United States have high LDL.2 The 2013 American College of Cardiology/American Heart Association guidelines recommend fasting cholesterol checks for all adults ages 21 and older for primary prevention of cardiovascular disease.3 The US Preventive Services Task Force (USPSTF) has long recommended screening cholesterol in adults to prevent atherosclerotic vascular disease.

In 2008, the USPSTF recommended lipid screening for all men ages 35 and older, for all men ages 20 to 35 who are at increased risk for coronary heart disease, and for all women ages 20 and older who are at increased risk for coronary heart disease.4 The ­USPSTF recommends TC and HDL as the preferred screening tests and states that these can be performed on fasting or nonfasting samples; however, if LDL is added, a fasting sample is recommended.4 Other national and international guidelines on cholesterol management also recommend a fasting lipid panel to stratify patients’ risk and determine treatment options.5-7

LDL usually is reported as a calculated value using the Friedewald equation (LDL equals TC minus HDL minus [triglycerides divided by 5]).8 This calculation is not accurate for patients with triglyceride levels > 400 mg/dL, which has prompted most authorities to recommend a fasting sample. That’s because while TC and HDL are not affected by food (and LDL may vary by only 10% or less), triglycerides can fluctuate by 20% to 30%, which would influence the calculation of a nonfasting LDL.9,10 LDL can be measured directly, but the process is generally expensive and not commonly used.11

The CDC estimates that more than 20% of US adults (48 million people) have not had a screening lipid panel in the previous five years.12 One barrier to screening is that both clinicians and patients often believe that a fasting specimen is required. Yet fasting specimens are difficult to obtain because they often require a separate visit to the clinic, which can result in lost time from work and additional transportation costs.

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