처음으로 lipid profile 검사를 하거나, 이미 알고 있는 고중성지방혈증의 추적 검사를 하는 경우는 예외로 하고, lipid profile은 대부분의 경우에 공복을 필요로 하지 않습니다. 그러나 대부분의 전문가들은 고중성지방으로 인한 부정확환 LDL-C 우려로 인하여, 반복적 검사를 하지 않기 위해 일상적으로 추적 lipid profile 검사를 위해서 환자에게 공복하도록 합니다.
With the exceptions of the first time a lipid profile is obtained or when the test is obtained for the purpose of following known hypertriglyceridemia, the lipid profile (or its components) does not require fasting in most cases. However, many experts routinely ask their patients to fast for a follow-up lipid profile so that there is no need to repeat the test due to a concern for an inaccurate low-density lipoprotein (LDL) cholesterol due to high triglycerides.
추적 lipid profile를 위해 환자가 공복할 것인지에 대한 결정은 환자의 편의성과 계산된 LDL-C 값이 증가된 TG로 인하여 부정확할 것 같은 개연성에 부분적으로 달려 있습니다.
The decision whether to have the patient fast for a subsequent lipid profile is in part dependent on patient convenience and the likelihood that the calculated LDL cholesterol value might be inaccurate due to elevated triglycerides.
계산된 LDL-C 값이 측정된 LDL-C 값과 의미 있게 다를 수 있는 높은 TG 위험이 있는 환자들은 제2형 당뇨병, 심한 비만, TG를 올리는 약을 복용 중인 사람, 의미 있는 알코올 음주 환자입니다.
Patients at increased risk for triglycerides high enough to make the calculated LDL cholesterol significantly different from a measured (direct) LDL cholesterol include those with type 2 diabetes, very obese individuals, those taking medications known to increase triglycerides, and patients with significant alcohol intake.
만일 non-fasting plasma TG 값이 400 mg/dL를 넘으면 우리는 공복 lipid profile 검사를 하며 TG 질환이 있는 환자를 추적 검사하거나 진단을 할 때 8-12시간을 공복하도록 합니다.
If the non-fasting plasma triglyceride component of the lipid profile returns at >4.516 mmol/L (400 mg/dL), we obtain a fasting lipid profile. We ask the patient to fast (8 to 12 hours without food) when we are attempting to diagnose or follow a patient with a triglyceride disorder. From a practical point of view, this means that the test will need to be obtained early in the morning (before breakfast). While mean population levels of triglycerides and calculated LDL cholesterol do not appear to vary substantially with different lengths of time since eating, clinically important variability in triglyceride levels in individual patients after consumption of fatty foods and drinks is likely and consistent with clinical experience.
총콜레스테롤과 HDL-C은 공복에 최소한으로 영향을 받습니다. 검사 이전에 fat을 복용하면 chylomicrons이 상승할 것이고 결과적으로 이 값이 증가되므로 계산된 LDL-C값은 실제보다도 낮아질 것입니다.
Total cholesterol and high-density lipoprotein (HDL) cholesterol are minimally affected by fasting. LDL cholesterol is typically calculated from total cholesterol, HDL cholesterol, and triglycerides using the Friedewald equation (LDL cholesterol = total cholesterol – HDL cholesterol – triglycerides x 0.2). This equation is modified for those with particularly elevated levels of triglycerides (>400 mg/dL), but even with modification is only accurate for patients who are fasting. In patients who have consumed fats prior to testing, various lipid components (eg, chylomicrons) will be elevated, which will result in a calculated LDL cholesterol that is falsely low compared with what would have been calculated in the fasting state.
The following serves to give a more detailed explanation of the potential impact of the results of a non-fasting test. If a patient has a lipid profile soon after eating a very fatty meal, chylomicrons are made to absorb the fat. The ratio of triglyceride to cholesterol in a chylomicron is about 20:1. In the fasting state, if there are no chylomicrons, then most of the triglyceride in the blood is being carried by very low-density lipoprotein (VLDL) and the triglyceride to cholesterol ratio in those particles is 5 to 1. That ratio is what most clinical laboratories use to calculate the cholesterol contribution of VLDL particles. If a patient has a fasting triglyceride of 100 mg/dL and their postprandial, fatty meal triglyceride was 300 mg/dL, then the VLDL cholesterol calculation would be performed and the VLDL cholesterol would be estimated at 300/5or 60 mg/dL. But if all the increased triglyceride (ie, the increase from 100 to 300 mg/dL) is due to chylomicrons, the actual VLDL plus chylomicron cholesterol is the 100/5(from the VLDL that are present) plus 200/20 which is the cholesterol in the chylomicrons. This amounts to a total of 30 mg/dL, not 60 mg/dL. The difference between the 60 mg/dL the laboratory would calculate and the 30 mg/dL which is the correct number to be using is 30 mg/dL, and that higher value would be wrongly subtracted to give an LDL cholesterol that is 30 mg/dL lower than it actually is. If a patient comes in and their fasting triglyceride is 100 mg/dL and their non-fasting triglyceride is 120 mg/dL, then the error in using the calculated LDL cholesterol is so small as not to matter. So, the key thing is that if there is a good record of fasting triglycerides in a patient and then a non-fasting one return with a much higher value, a very significant error could be introduced into the LDL cholesterol calculation if they use that non-fasting value.
9만명 이상을 대상으로 공복과 공복이 아닌 상태의 lipid 값을 비교한 큰 관찰 연구에서 식사 후 1-6시간에 최대 평균 변화는 임상적으로 의미가 없었습니다. TG + 26 mg/dL, 총콜레스테롤과 LDL-C, non-HDL은 - 8 mg/dL. HDL-C과 apolipoprotein A1, apolipoprotein B, Lp(a)는 변화가 없었습니다.
The largest observational study comparing fasting and non-fasting lipid values evaluated results in over 90,000 individuals. The following was noted:
● The maximal mean changes at one to six hours after habitual meals were thought to be clinically insignificant at +0.3 mmol/L (26 mg/dL) for triglycerides, -0.2 mmol/L (8 mg/dL) for total cholesterol and LDL cholesterol, and -0.2 mmol/L for calculated non-HDL cholesterol.
●Concentrations for HDL cholesterol, apolipoprotein A1, apolipoprotein B, and Lp(a) were unchanged.
Nonfasting lipid profiles may be used to calculate "remnant" cholesterol. Remnant cholesterol is either measured directly or calculated as: non-HDL cholesterol – directly measured LDL cholesterol. Remnant cholesterol has been confirmed in Mendelian randomization trials as a marker of myocardial infarction (MI) and in prospective observational studies as a predictor of initial and recurrent cardiovascular events
REF. UpToDate 2019.07.14
