From the Guidelines
To adjust cholesterol levels for a non-fasting patient, no adjustment is needed for total cholesterol and HDL cholesterol, while LDL cholesterol may be 10% lower and triglycerides may be up to 20% higher compared to fasting levels. According to the 2019 American College of Cardiology/American Heart Association guideline 1, nonfasting lipid profiles can be used for risk assessment in primary prevention and for assessment of baseline LDL-C levels before the initiation of a statin in primary and secondary prevention. The guideline suggests that fasting and nonfasting TC and HDL-C levels have fairly similar prognostic value and associations with CVD outcomes.
When considering the adjustment of cholesterol levels, it is essential to note that:
- Total cholesterol and HDL cholesterol levels do not require adjustment
- LDL cholesterol levels may be approximately 10% lower in nonfasting samples
- Triglyceride levels may be up to 20% higher in nonfasting samples, as stated in the 2015 VA/DoD clinical practice guideline 1
However, if the non-fasting triglycerides are very high (>400 mg/dL), the calculated LDL may be inaccurate, and a direct LDL measurement or a fasting sample would be preferable, as mentioned in the 2015 VA/DoD clinical practice guideline 1. For most patients, especially for initial screening, non-fasting lipid panels are sufficient for risk assessment and treatment decisions, as the differences between fasting and non-fasting values are typically modest.
Key points to consider:
- Nonfasting lipid profiles can be used for risk assessment and treatment decisions
- Fasting lipid measures may be necessary if triglyceride levels are very high or if more precision is required
- The 2019 American College of Cardiology/American Heart Association guideline 1 supports the use of nonfasting lipid profiles for most patients.
From the Research
Adjusting Cholesterol Levels for Non-Fasting Patients
To adjust cholesterol levels for use if a patient was not fasting, several studies provide guidance on the interpretation and application of non-fasting lipid profiles.
- The primary lipid targets are plasma total cholesterol and low-density lipoprotein-cholesterol (LDL-C) levels, but triglycerides, apolipoprotein (apo) B, and non-high-density lipoprotein-cholesterol (non-HDL-C) are also suitable parameters to assess cardiovascular risk and guide lipid-lowering therapy 2.
- Non-fasting lipid profiles can be used in daily clinical practice, and the advantage of using these variables is that they can be used in both the fasting and non-fasting state 2.
- Lipids and lipoproteins only change minimally in response to normal food intake, with maximal mean changes of +0.3 mmol/L (26 mg/dL) for triglycerides, -0.2 mmol/L (8 mg/dL) for total cholesterol, -0.2 mmol/L (8 mg/dL) for LDL cholesterol, and -0.1 mmol/L (4 mg/dL) for HDL cholesterol 3.
- Non-fasting samples rather than fasting samples have many obvious advantages, including simplifying blood sampling in the laboratory, benefiting the patient by avoiding the inconvenience of fasting, and minimizing the risk of hypoglycemia due to fasting for individuals with diabetes 3.
- For non-fasting samples, laboratory reports should flag abnormal concentrations as triglycerides ≥2 mmol/L (175 mg/dL), total cholesterol ≥5 mmol/L (190 mg/dL), LDL cholesterol ≥3 mmol/L (115 mg/dL), calculated remnant cholesterol ≥0.9 mmol/L (35 mg/dL), calculated non-HDL cholesterol ≥3.9 mmol/L (150 mg/dL), HDL cholesterol ≤1 mmol/L (40 mg/dL), apolipoprotein A1 ≤1.25 g/L (125 mg/dL), apolipoprotein B ≥1.0 g/L (100 mg/dL), and lipoprotein(a) ≥50 mg/dL (80th percentile) 4.
Clinical Implications
- The use of non-fasting lipid profiles can improve patient compliance with lipid testing and simplify blood sampling for patients, laboratories, and clinicians worldwide 3, 4.
- Non-fasting and fasting concentrations vary similarly over time and are comparable in the prediction of cardiovascular disease 3, 4.
- Fasting sampling may be considered when non-fasting triglycerides >5 mmol/L (440 mg/dL) 4.