Nonfasting Lipids OK for Initial Testing; Labs Urged to Use ‘Desirable’ Cut-Offs to Flag Results

Non-fasting lipid profiles are recommended for most patients, including for cardiovascular risk assessment, according to a joint statement published by the European Atherosclerosis Society and European Federation of Clinical Chemistry and Laboratory Medicine April 26 in the European Heart Journal. The panel recommendations are expected to improve patient compliance with lipid testing, while laboratory flagging of abnormal values, based on desirable concentration cut-points, rather than by reference intervals, is called for.

Traditionally, lipid profiles have been measured using samples collected after fasting for at least eight hours, which does not reflect the daily average plasma lipid and lipoprotein concentrations and associated risk of cardiovascular disease, since most people are in a non-fasting state for the majority of the day. Recently, though, “extensive” evidence show that changes in lipid and lipoprotein protein levels after a meal are only “modest” and not clinically significant for triglycerides, total cholesterol, LDL cholesterol or calculated remnant cholesterol, while concentrations of HDL cholesterol, apolipoprotein A1 and B, and lipoprotein(a) are not affected by fasting status.

“Numerous prospective cohorts have found significant associations for non-fasting lipids, lipoproteins, and apolipoproteins with cardiovascular disease risk, and several landmark clinical trials of statin therapy have used non-fasting lipids for trial entry criteria and for monitoring the efficacy of lipid-lowering therapy,” the panel noted. “Collectively, these observations suggest that non-fasting blood sampling is highly effective, practical, and advantageous in assessing lipid-mediated cardiovascular disease risk and treatment responses.”

The panel recommends that fasting is not required for routine plasma lipid profile or for cardiovascular risk assessment in most patients, including children, diabetic patients, and the elderly. They also suggest that for non-fasting samples, laboratory reports should flag abnormal concentrations as triglycerides ≥2 mmol/L, total cholesterol ≥5 mmol/L, LDL cholesterol ≥3 mmol/L, calculated remnant cholesterol ≥0.9 mmol/L, calculated non-HDL cholesterol ≥3.9 mmol/L, HDL cholesterol ≤1 mmol/L, apolipoprotein A1 ≤1.25 g/L, apolipoprotein B ≥1.0 g/L, and lipoprotein(a) ≥50 mg/dL (80th percentile).

However, the panel still recommends fasting when non-fasting plasma triglyceride concentration >5 mmol/L, a patient has known hypertriglyceridemia, is starting medications associated with severe hypertrigylceridemia, and following hypertriglyceridemic pancreatititis.

Additionally, in areas where fast food consumption is especially high, fasting may be recommended or patients can be warned to avoid high-fat food the day of the test. “Fasting is less critical for first-stage screening, but may be more important when trying to establish a phenotypic diagnosis of genetically determined dyslipidaemias,” the panel writes.