Abstract
BackgroundCurrent guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels.MethodSubjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1–4 h, 4–8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression.ResultsAt multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1–4 h and p = 0.0147 for 4–8 h among females; p < 0.0001 for 1–4 h and p = 0.0002 for 4–8 h among males) and reduced LDL cholesterol levels (p = 0.0003 for 1–4 h and p = 0.0327 for 4–8 h among males). Among males, hepatic steatosis represents an independent factor affecting elevated total cholesterol (p = 0.0278) and triglyceride concentrations (p = 0.0002).ConclusionTotal and HDL cholesterol concentrations are subject to slight variations in relation to the duration of the pre-phlebotomy fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis.
Highlights
Current guidelines recommend measuring plasma lipids in fasting patients
Fasting time represents an independent factor for reduced Low-density lipoprotein (LDL) cholesterol and elevated triglyceride concentrations
With these considerations in mind, we investigated the effects of the duration of pre-phlebotomy fasting time as well as other factors, such as age, body-mass index (BMI), waist-to-hip ratio (WHR) and alcohol consumption of the plasma concentrations of total cholesterol, High-density lipoprotein (HDL) and LDL cholesterol, and triglycerides in a populationbased subject collective
Summary
Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). The current guidelines (2001) of the National Cholesterol Education Program (NCEP) recommend that measurement of serum lipids, especially of LDL cholesterol and triglycerides, be performed in fasting patients [1]. The objective is to minimize individual variations in lipid levels, especially of LDL cholesterol and triglycerides, and to ensure that patients’ metabolic condition at the time of phlebotomy is comparable [2,3]. A few studies, some of them in large subject collectives, that investigated variations in lipid concentrations in relation to the duration of subjects’ fasting period, observed only slight variation and came to the conclusion that fasting is not an absolute requirement for measurement of HDL, LDL and total cholesterol [4,5,6,7]. Because humans normally are in a non-fasting condition during much of the day, it might be argued that lipid measurements obtained in a non-fasting subject are more representative of the current metabolic status and may provide better evidence for potential disorders of postprandial lipid metabolism [1,2,9,12,13]
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