Fasting or Nonfasting Lipid Measurements?
- Driver SL, Martin SS, Gluckman TJ, Clary JM, Blumenthal RS, Stone NJ.
- Fasting or Nonfasting Lipid Measurements: It Depends on the Question. J Am Coll Cardiol 2016;67:1227-1234.
The following are key points to remember about when and whether to take fasting or nonfasting lipid measurements:
- Measurement of lipids has traditionally been recommended to be when the patient is fasting. With current guidelines, low-density lipoprotein (LDL) cholesterol values may not be needed for some clinical scenarios. For several risk estimators, LDL is not included, but rather total cholesterol and high-density lipoprotein (HDL) cholesterol, both of which vary little between the fasting and nonfasting state. Therefore, in the estimation of initial risk among the primary prevention patients who are not on lipid-lowering therapy, nonfasting lipid measurements would be acceptable.
- The screening and follow-up of patients with a family history of genetic (familial) hyperlipidemia and/or premature atherosclerotic cardiovascular disease (ASCVD) is recommended. An LDL cholesterol >190 mg/dl is the most common result suggestive of familial hyperlipidemia. Thus, a fasting measure is recommended.
- Assessment of metabolic parameters which define metabolic syndrome can assist the provider and patient to initiate changes, in particular lifestyle changes, which reduce risk of diabetes and CVD. Ideally, measurement of lipids such as triglycerides (a criterion of the metabolic syndrome) is recommended to be measured in the fasting state. However, nonfasting measures including triglycerides >200 mg/dl and a low HDL (40 mg/dl in men or <50 mg/dl in women), in the setting of a hemoglobin A1c >5.6% would be consistent with traditional metabolic criteria and thus allow for theraputic interventions to begin soon after results are measured. Thus, the authors of the commentary recommend that for the assessment of metabolic syndrome, nonfasting would be acceptable.
- In a recent statement on hypertriglyceridemia, the American Heart Association suggested that providers could use nonfasting triglycerides >200 mg/dl to identify hypertriglyceridemic states. In most cases, when an elevated result is observed, then a repeat fasting triglyceride can be measured in 2-4 weeks. In the cases when extreme levels are observed, for example approximately 1000 mg/dl, there is no need for repeat of fasting lipids prior to treatment.
- Patients with pancreatitis should have a fasting lipid profile checked to assess for a triglyceride level >500 mg/dl. Patients at risk for hypertriglyceridemia include those with human immunodeficiency virus treated with antiretroviral therapy, patients treated with long-term steroids, patients with a family history of hypertriglyceridemia or visceral adiposity who are starting an oral contraceptive or hormone replacement therapy, and women who are planning to get pregnant.
- For the patient currently treated with lipid-lowering therapies, assessment of factors including diet, physical activity, smoking status, blood pressure, and glucose are important modifiable components of CVD risk, beyond LDL levels. Moderate- and high-intensity statin therapy generally results in a relative risk reduction of 20% per 1 mmol/L (39 mg/dl) of LDL lowering. Comparision of LDL levels pre- and post-statin therapy can estimate the relative risk reduction obtained; thus, a fasting measure can be recommended.
- A fasting lipid profile among treated patients provides prognostic value with regard to risk for statin-induced diabetes, as a triglyceride level <150 mg/dl is associated with a lower risk of diabetes. Prognostic value is also present with lower treated LDL with regard to acute coronary syndrome incidence.
- Adherence to therapy is important for all treated patients. Providing patients with a review of the trends over time in their lipid profile allows for a discussion of the risk reduction afforded with lower LDL and non-HDL levels. Even among those in whom the clinician does not have pretreatment values, assessment of fasting lipids can allow for detection of changes related to adherence for statins and/or lifestyle factors. Thus, a fasting measure is recommended.
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