From the Guidelines
Your cholesterol test results will likely be reliable even if you had milk 2 hours before the test, as non-fasting lipid profiles provide acceptably accurate measures for risk calculation. According to the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA guideline on the management of blood cholesterol 1, nonfasting samples 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 nonfasting TC and HDL-C levels appear to have fairly similar prognostic value and associations with CVD outcomes.
Some key points to consider:
- Nonfasting lipid profiles provide measures of total cholesterol and HDL-C levels that differ little from measures after a 9- to 12-hour fast 1.
- Compared with fasting measures, nonfasting LDL-C level may be 10% lower and triglyceride levels may be as much as 20% higher 1.
- The small variance in LDL-C level is unlikely to affect classification of risk or therapeutic decisions 1.
- If triglyceride levels are greater than 4.52 mmol/L (>400 mg/dL), the Friedewald equation commonly used to calculate LDL-C levels may not be accurate, and fasting lipid measures may be necessary 1.
It's essential to inform your healthcare provider about the milk consumption before the test, so they can interpret your results accordingly or possibly reschedule the test if necessary. For future cholesterol tests, follow your doctor's specific instructions about fasting requirements.
From the Research
Reliability of Cholesterol Test Results
- The reliability of cholesterol test results after consuming milk 2 hours before the test can be assessed based on several studies that have investigated the effect of food intake on lipid profiles.
- A study published in Circulation in 2008 found that lipid profiles change minimally in response to normal food intake, with maximum changes of -0.2 mmol/L for total cholesterol, -0.2 mmol/L for low-density lipoprotein cholesterol, -0.1 mmol/L for HDL cholesterol, and 0.3 mmol/L for triglycerides 2.
- Another study published in the Journal of the Medical Association of Thailand in 2016 found that fasting for 8 hours before measurement of serum triglyceride levels may be sufficient, with no significant difference in triglyceride levels between patients who had fasted for 8 hours and those who had fasted for 12 hours 3.
Impact of Food Intake on Lipid Profiles
- A study published in the Canadian Family Physician in 2014 found that total cholesterol, high-density lipoprotein cholesterol, and non-low-density lipoprotein cholesterol all varied by an average of 2% with fasting status, suggesting that nonfasting cholesterol measurement is a reasonable alternative to fasting cholesterol measurement for routine screening 4.
- A study published in Pathology in 2019 found that nonfasting triglycerides are superior to fasting triglycerides in predicting cardiovascular risk, and that lipids and lipoproteins only change minimally in response to normal food intake 5.
- A study published in the Journal of the American College of Cardiology in 2017 found that nonfasting lipid profiles represent a simplification without negative implications for prognostic, diagnostic, and therapeutic options for cardiovascular disease prevention, with maximal mean changes of +26 mg/dl for triglycerides, -8 mg/dl for total cholesterol, -8 mg/dl for low-density lipoprotein cholesterol, and -8 mg/dl for non-high-density lipoprotein cholesterol 6.