Comparison of non-fasting LDL-C levels calculated by Friedewald formula with those directly measured in Chinese patients with coronary heart disease after a daily breakfast

Association Between Remnant Cholesterol and Nonalcoholic Fatty Liver Disease: A Systemic Review and Meta-Analysis

Lipid disorders are related to the risk of nonalcoholic fatty liver disease (NAFLD). Remnant cholesterol (RC), a nonclassical and once-neglected risk factor for NAFLD, has recently received new attention. In this study, we assessed the relationship between the RC levels and NAFLD risk. We searched across PubMed, Web of Science, Embase, Cochrane Library, and China National Knowledge Infrastructure, with no restrictions on publication languages. Retrospective cohort studies and cross-sectional studies were enrolled from the inception of the databases until August 6, 2023. A random-effect model was applied to construct the mean difference, and a 95% confidence interval was applied to assess the relationship between the RC levels and NAFLD risk. We used two methods to estimate RC levels: Calculated-1 subtracts low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol from total cholesterol; Calculated-2 uses the Friedewald formula for LDL-C when triglycerides are <4.0 mmol/L, otherwise directly measured. A total of 265 published studies were selected through preliminary retrieval. Of these, six studies met the inclusion requirements and were enrolled in the meta-analysis. The RC level in the NAFLD group was significantly higher than that in the non-NAFLD group (mean difference: 0.18, 95% confidence interval: 0.10-0.26, P < 0.00001). We conducted subgroup analyses of computational methods and geographic regions. Notably, in the subgroup analysis of Calculation Method 2, the NAFLD group had significantly higher RC levels than the non-NAFLD group. On the other hand, in Calculation Method 1, the difference between the two groups was insignificant. In both the Asian and non-Asian populations, the RC levels were significantly higher in the NAFLD group than in the non-NAFLD group. The association of RC with an increased NAFLD risk was not dependent on the triglyceride. This meta-analysis suggests that elevated RC levels are associated with an increased risk of NAFLD. In addition to the conventional risk factors for fatty liver, clinicians should be concerned about the RC levels in the clinic.

Postprandial triglyceride-rich lipoproteins promote the adipogenic differentiation of adipose-derived mesenchymal stem cells via the LRP1/caveolin-1/AKT1 pathway

Diet-induced obesity (OB) is usually accompanied by hypertriglyceridemia, which is characterized by the accumulation of triglyceride (TG)-rich lipoprotein (TRL) particles in the circulation. We previously found that postprandial TRL combined with insulin induced the adipogenic differentiation of 3T3-L1 preadipocytes, which may represent a key mechanism underlying obesity. However, the specific mechanism and signaling pathway involved in this process remain to be fully elucidated. In this study, we found that, in the postprandial state, patients with obesity had significantly higher levels of TG and remnant cholesterol (RC) than normal-weight controls. In vitro, we found that postprandial TRL, together with insulin, promoted the adipogenic differentiation of adipose-derived mesenchymal stem cells (AMSCs), as evidenced by the increased expression of lipogenesis-related genes and their protein products, including low-density lipoprotein related protein 1 (LRP1). Besides, caveolin-1 (Cav-1) expression was also significantly upregulated under this condition. Cav-1 and LRP1 were observed to interact, and then led to the activation of the PI3K/AKT1 signaling pathway. Meanwhile, the inhibition of LRP1 or Cav-1 significantly attenuated the adipogenic differentiation of AMSCs and downregulated AKT1 phosphorylation levels. Moreover, treatment with a selective AKT1 inhibitor significantly suppressed postprandial TRL and insulin-induced adipogenesis in AMSCs. Combined, our results demonstrated that, in association with insulin, postprandial TRL can promote the adipogenic differentiation of AMSCs in a manner that is dependent on the LRP1/Cav-1-mediated activation of the PI3K/AKT1 signaling pathway. Our findings indicated that a postprandial increase in TRL content is a critical factor in the pathogenesis of hypertriglyceridemia and diet-induced obesity.

Non-fasting changes of Hs-CRP level in Chinese patients with coronary heart disease after a daily meal

High-sensitivity C-reactive protein (hs-CRP) is a key inflammatory factor in atherosclerotic cardiovascular diseases. In Chinese patients with coronary heart disease (CHD), the changes in hs-CRP levels after a daily meal and the effect of statins on those were never explored. A total of 300 inpatients with CHD were included in this study. Hs-CRP levels were measured in the fasting and non-fasting states at 2 h and 4 h after a daily breakfast. All inpatients were divided into two groups according to fasting hs-CRP ≤ 3 mg/L or not. Group with fasting hs-CRP ≤ 3 mg/L had a significantly higher percentage of patients with statins using ≥ 1 month (m) before admission than that with fasting hs-CRP > 3 mg/L (51.4% vs. 23.9%, P < 0.05). Hs-CRP levels increased significantly in the non-fasting state in two groups (P < 0.05). About 32% of patients with non-fasting hs-CRP > 3 mg/L came from those with fasting hs-CRP ≤ 3 mg/L. In conclusion, hs-CRP levels increased significantly in CHD patients after a daily meal. It suggested that the non-fasting hs-CRP level could be a better parameter to evaluate the inflammation state of CHD patients rather than fasting hs-CRP level.

The accuracy of four formulas for LDL-C calculation at the fasting and postprandial states

Background

Elevated level of low-density lipoprotein cholesterol (LDL-C) is concerned as one of the main risk factors for cardiovascular disease, in both the fasting and postprandial states. This study aimed to compare the measured LDL-C with LDL-C calculated by the Friedewald, Martin–Hopkins, Vujovic, and Sampson formulas, and establish which formula could provide the most reliable LDL-C results for Chinese subjects, especially at the postprandial state.

Methods

Twenty-six subjects were enrolled in this study. The blood samples were collected from all the subjects before and after taking a daily breakfast. The calculated LDL-C results were compared with LDL-C measured by the vertical auto profile method, at both the fasting and postprandial states. The percentage difference between calculated and measured LDL-C (total error) and the number of results exceeding the total error goal of 12% were established.

Results

The calculated LDL-C_F levels showed no significant difference from LDL-C_VAP levels at the fasting state. The calculated LDL-C_S were significantly higher than LDL-C_VAP at the fasting state (P < 0.05), while the calculated LDL-C_s were very close to LDL-C_VAP levels after a daily meal. At the fasting state, the median total error of calculated LDL-C_F was 0 (quartile: −3.8 to 6.0), followed by LDL-C_S, LDL-C_MH, and LDL-C_V. At the postprandial states, the median total errors of LDL-C_S were the smallest, 1.0 (−7.5, 8.5) and −0.3 (−10.1, 10.9) at 2 and 4 h, respectively. The calculated LDL-C_F levels showed the highest correlation to LDL-C_VAP and accuracy in evaluating fasting LDL-C levels, while the Sampson formula showed the highest accuracy at the postprandial state.

Conclusion

The Friedewald formula was recommended to calculate fasting LDL-C, while the Sampson formula seemed to be a better choice to calculate postprandial LDL-C levels in Chinese subjects.

Comparative Study of Calculated LDL-Cholesterol Levels with the Direct Assay in Patients with Hypothyroidism

Background Hypothyroidism is one among the many factors that predisposes one to coronary artery disease. As low-density lipoprotein-cholesterol (LDL-C) is associated with cardiovascular risk, calculated LDL-C should have good accuracy with minimal bias. Hypothyroidism alters the lipid composition of lipoproteins by the secretion of triglyceride-rich lipoproteins, which affects the calculation of LDL-C. The present study aimed to compare 13 different formulae for the calculation of LDL-C including the newly derived Martin's formula by direct assay in patients of hypothyroidism.

Method In this analytical cross-sectional study, a total of 105 patients with laboratory evidence of hypothyroidism, from January to June 2019, were studied, and blood samples were subjected for lipid profile analysis at central biochemistry laboratory. Calculated LDL-C was assessed by different formulae.

Result We observed that calculated LDL-C by Friedewald's, Cordova's, Anandaraja's, Hattori's, and Chen's formulae has bias less than ± 5 compared with direct LDL-C, with Anandaraja's formula having the lowest bias (2.744) and Cordova's formula having lowest bias percentage (−1.077) among them. According to the Bland–Altman plots, the bias in Friedewald's and Anandraja's were equally distributed below and above the reference line of direct LDL-C.

Conclusion This is the first study comparing different formulae for LDL-C calculation in patients with hypothyroidism. Anandaraja's formula was as equally effective as Friedewald's formula when used as an alternative cost-effective tool to evaluate LDL-C in hypothyroid patients. The recently proposed Martin's formula for calculated LDL-C had a higher bias when compared with Friedewald's and Anandaraja's formulae in patients with hypothyroidism.

The Mechanism of Dendrobium officinale as a Treatment for Hyperlipidemia Based on Network Pharmacology and Experimental Validation

Aim and Objective. Hyperlipidemia is a public health matter of global scale, contributing to a wide range of diseases that can result in severe complications and significant annual mortality. Dendrobium officinale (DO) is an edible plant with a long medicinal history in China. Our previous studies revealed that DO may have therapeutic benefits in lipid disorders. However, the mechanism of its active compounds is still unclear. This research aimed at uncovering the hidden anti-hyperlipidemia mechanisms of DO through network pharmacology and experimental validation. Materials and Methods. The active compounds in DO, their targets, and targets associated with hyperlipidemia were screened across various databases, and the hidden targets of DO in treating hyperlipidemia were forecast. The compound-target (C-T), protein-protein interaction (PPI), and compound-target-pathway (C-T-P) networks of DO were set up with Cytoscape software. The hub genes and core clusters of DO predicted to be active against hyperlipidemia were calculated by Cytoscape. The DAVID database was adopted for Gene Ontology (GO) analysis and KEGG pathway enrichment analysis. Next, we used the high-sucrose-fat diet and alcohol (HFDA)-induced hyperlipidemia rats to evaluate the hypolipidemic effect of DO. Results. In this study, we obtained 264 compounds from DO, revealed 11 bioactive compounds, and predicted 89 potential targets of DO. The network analysis uncovered that naringenin, isorhamnetin, and taxifolin might be the compounds in DO that are mainly in charge of its roles in hyperlipidemia and might play a role by modulating the targets (including PPARG, ADIPOQ, AKT1, TNF, and APOB). The pathway analysis showed that DO might affect diverse signaling pathways related to the pathogenesis of hyperlipidemia, including PPAR signaling pathway, insulin resistance, AMPK signaling pathway, and non-alcoholic fatty liver disease simultaneously. Meanwhile, in the HFDA-induced hyperlipidemia rat model, DO could significantly decrease the level of TC, TG, LDL-c, and ALT in serum, and increase HDL-c as well. The liver pathological section indicated that DO could ease liver damage and lipid cumulation. Conclusion. In summary, the biological targets of the main bioactive compounds in DO were found to distribute across multiple metabolic pathways. These findings suggest that a mutual regulatory system consisting of multiple components, targets, and pathways is a likely mechanism through which DO may improve hyperlipidemia. Validation experiments indicated that DO may treat hyperlipidemia by affecting NAFLD-related signaling pathways.

Non-fasting Changes in Blood Lipids After Three Daily Meals Within a Day in Chinese Inpatients With Cardiovascular Diseases

Background

Non-fasting (i.e., postprandial) lipid detection is recommended in clinical practice. However, the change in blood lipids in Chinese patients with cardiovascular diseases after three daily meals has never been reported yet.

Methods

Serum levels of blood lipids were measured or calculated in 77 inpatients (48 men and 29 women) at high or very high risk of atherosclerotic cardiovascular disease (ASCVD) in the fasting state and at 4 h after three meals within a day according to their diet habits.

Results

Female patients showed significantly higher level of high-density lipoprotein cholesterol (HDL-C) than male patients, and the gender difference in other lipid parameters did not reach statistical significance at any time-point. Levels of triglyceride (TG) and remnant cholesterol (RC) increased, while that of low-density lipoprotein cholesterol (LDL-C) decreased significantly after three meals (p < 0.05). Levels of HDL-C, total cholesterol (TC), and non-high-density lipoprotein cholesterol (non-HDL-C) showed smaller changes after three meals. Percent reductions in the non-fasting LDL-C levels after lunch and supper were around 20%, which were greater than that after breakfast. The percent reductions in the non-fasting non-HDL-C levels after three meals were smaller than those in the non-fasting LDL-C levels. Patients with TG level ≥ 2.0 mmol/L (177 mg/dL) after lunch had significantly greater absolute reduction of LDL-C level than those with TG level < 2.0 mmol/L (177 mg/dL) after lunch [–0.69 mmol/L (–27 mg/dL) vs. –0.36 mmol/L (–14 mg/dL), p<0.01]. There was a significant and negative correlation between absolute change in LDL-C level and that in TG level (r = −0.32) or RC level (r = −0.67) after lunch (both p<0.01).

Conclusion

LDL-C level decreased significantly after three daily meals in Chinese patients at high or very high risk of ASCVD, especially when TG level reached its peak after lunch. Relatively, non-HDL-C level was more stable than LDL-C level postprandially. Therefore, when LDL-C level was measured in the non-fasting state, non-HDL-C level could be evaluated simultaneously to reduce the interference of related factors, such as postprandial hypertriglyceridemia, on detection.

Non-fasting lipid profile for cardiovascular risk assessments using China ASCVD risk estimator and Europe SCORE risk charts in Chinese participants

Background

Previous studies have shown that non-fasting lipids have similar values in cardiovascular risk estimation as fasting, but it is not clear whether this could also be applicable to Chinese participants.

Methods

A total of 127 (76 men, 51 women) participants without atherosclerotic cardiovascular diseases (ASCVD) were enrolled in the study. Serum levels of blood lipids were monitored at 0 h, 2 h and 4 h after a daily breakfast. Ten-year cardiovascular disease (CVD) risk was estimated with China ASCVD risk estimator and European SCORE risk charts. Kappa statistic was used to determine agreement among estimators.

Results

China ASCVD risk estimator assessed half of the participants as low risk, while European risk charts assessed half of the participants as moderate risk in the same participants. Reliability analysis in China ASCVD risk estimator and Europe SCORE risk charts based on fasting and or non-fasting lipids profile were relatively high (Kappa =0.731 or 0.718, P<0.001), (Kappa =0.922 or 0.935, P<0.001) (Kappa =0.886 or 0.874, P<0.001), but agreement between two were relatively poor in both fasting and non-fasting states (Kappa =0.339 or 0.300, P<0.001), (Kappa =0.364 or 0.286, P<0.001).

Conclusions

Promoting use of non-fasting lipids in diagnosis, evaluation, and prediction of CVD are feasible. Furthermore, non-fasting lipids could be used in China ASCVD risk estimator to evaluate 10-year risk of ASCVD among Chinese general participants.

Comparison of the Reductions in LDL-C and Non-HDL-C Induced by the Red Yeast Rice Extract Xuezhikang Between Fasting and Non-fasting States in Patients With Coronary Heart Disease

Background: Xuezhikang, an extract of red yeast rice, effectively lowers fasting blood lipid levels. However, the influence of Xuezhikang on the non-fasting levels of low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C) has not been explored in Chinese patients with coronary heart disease (CHD).

Methods: Fifty CHD patients were enrolled and randomly divided into two groups (n = 25 each) to receive 1,200 mg/d of Xuezhikang or a placebo for 6 weeks as routine therapy. Blood lipids were repeatedly measured before and after 6 weeks of treatment at 0, 2, 4, and 6 h after a standard breakfast containing 800 kcal and 50 g of fat.

Results: The serum LDL-C levels significantly decreased, from a fasting level of 3.88 mmol/L to non-fasting levels of 2.99, 2.83, and 3.23 mmol/L at 2, 4, and 6 h, respectively, after breakfast (P < 0.05). The serum non-HDL-C level mildly increased from a fasting level of 4.29 mmol/L to non-fasting levels of 4.32, 4.38, and 4.34 mmol/L at 2, 4, and 6 h post-prandially, respectively, and the difference reached statistical significance only at 4 and 6 h after breakfast (P < 0.05). After 6 weeks of Xuezhikang treatment, the patients had significantly lower fasting and non-fasting serum levels of LDL-C and non-HDL-C (P < 0.05) than at pretreatment. The LDL-C levels were reduced by 27.8, 28.1, 26.2, and 25.3% at 0, 2, 4, and 6 h, respectively, and the non-HDL-C levels were reduced by 27.6, 28.7, 29.0, and 28.0% at 0, 2, 4, and 6 h, respectively, after breakfast. No significant difference was found in the percent reductions in the LDL-C and non-HDL-C levels among the four different time-points.

Conclusions: Six weeks of Xuezhikang treatment significantly decreased LDL-C and non-HDL-C levels, with similar percent reductions in fasting and non-fasting states in CHD patients, indicating that the percent change in non-fasting LDL-C or non-HDL-C could replace that in the fasting state for evaluation the efficacy of cholesterol control in CHD patients who are unwilling or unable to fast.

The Role of Fasting LDL-C Levels in Their Non-fasting Reduction in Patients With Coronary Heart Disease

The level of low-density lipoprotein cholesterol (LDL-C) decreases to a certain extent after daily meals; however, the influencing factor of this phenomenon has not been fully elucidated. This study included 447 patients with coronary heart disease (CHD). Serum levels of blood lipid parameters at 0, 2, and 4 hours (h) after a daily breakfast were monitored in all subjects. The levels of total cholesterol (TC), LDL-C, high-density lipoprotein cholesterol (HDL-C) and non-HDL-C significantly decreased, while those of triglycerides (TG) and remnant cholesterol (RC) significantly increased from baseline to 4 h in both male and female patients (P < 0.05). Multiple linear regression analysis showed that fasting LDL-C level, the non-fasting change in RC level at 4 h and fasting TG level were significant predictors of the non-fasting change in LDL-C level at 4 h in patients with CHD, and fasting LDL-C level was the most significantly associated with the non-fasting change in LDL-C level. Patients with lower levels of fasting LDL-C had smaller non-fasting changes in LDL-C levels. When the fasting LDL-C level was <1.4 mmol/L, both absolute reduction and percent reduction in LDL-C level at 4 h were almost zero, which means that the non-fasting LDL-C level at 4 h was approximately equivalent to its fasting value (P < 0.05). This result indicated that the non-fasting changes in LDL-C levels were influenced by fasting LDL-C levels in patients with CHD. When the fasting LDL-C level was <1.4 mmol/L, the non-fasting LDL-C level could replace the fasting value to guide treatment.

Change in Postprandial Level of Remnant Cholesterol After a Daily Breakfast in Chinese Patients With Hypertension

Background: Hypertension (HBP) is usually accompanied by hypertriglyceridemia that represents the increased triglyceride-rich lipoproteins and cholesterol content in remnant lipoproteins [i.e., remnant cholesterol (RC)]. According to the European Atherosclerosis Society (EAS), high RC (HRC) is defined as fasting RC ≥0.8 mmol/L and/or postprandial RC ≥0.9 mmol/L. However, little is known about postprandial change in RC level after a daily meal in Chinese patients with HBP. Methods: One hundred thirty-five subjects, including 90 hypertensive patients (HBP group) and 45 non-HBP controls (CON group), were recruited in this study. Serum levels of blood lipids, including calculated RC, were explored at 0, 2, and 4 h after a daily breakfast. Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff point of postprandial HRC. Results: Fasting TG and RC levels were significantly higher in the HBP group (P < 0.05), both of which increased significantly after a daily meal in the two groups (P < 0.05). Moreover, postprandial RC level was significantly higher in the HBP group (P < 0.05). ROC curve analysis showed that the optimal cutoff point for RC after a daily meal to predict HRC corresponding to fasting RC of 0.8 mmol/L was 0.91 mmol/L, which was very close to that recommended by the EAS, i.e., 0.9 mmol/L. Fasting HRC was found in 31.1% of hypertensive patients but not in the controls. According to the postprandial cutoff point, postprandial HRC was found in approximately half of hypertensive patients and ~1-third of the controls. Conclusion: Postprandial RC level increased significantly after a daily meal, and hypertensive patients had higher percentage of HRC at both fasting and postprandial states. More importantly, the detection of postprandial lipids could be helpful to find HRC.

Chinese Guideline on the Primary Prevention of Cardiovascular Diseases

Abstract

Cardiovascular disease is the leading cause of mortality in China. Primary prevention of cardiovascular disease with a focus on lifestyle intervention and risk factor control has been shown to effectively delay or prevent the occurrence of cardiovascular events. To promote a healthy lifestyle and enhance the detection, diagnosis, and treatment of cardiovascular risk factors such as hypertension, dyslipidemia, and diabetes, and to improve the overall capacity of primary prevention of cardiovascular disease, the Chinese Society of Cardiology of Chinese Medical Association has collaborated with multiple societies to summarize and evaluate the latest evidence with reference to relevant guidelines and subsequently to develop recommendations for primary cardiovascular disease prevention in Chinese adults. The guideline consists of 10 sections: introduction, methodology for developing the guideline, epidemiology of cardiovascular disease in China and challenges in primary prevention, general recommendations for primary prevention, assessment of cardiovascular risk, lifestyle intervention, blood pressure control, lipid management, management of type 2 diabetes, and use of aspirin. The promulgation and implementation of this guideline will play a key role in promoting the practice of primary prevention for cardiovascular disease in China.

Non-HDL-C Is More Stable Than LDL-C in Assessing the Percent Attainment of Non-fasting Lipid for Coronary Heart Disease Patients

This study aimed to compare the percentage attainment of fasting and non-fasting LDL-C and non-HDL-C target levels in coronary heart disease (CHD) patients receiving short-term statin therapy. This study enrolled 397 inpatients with CHD. Of these, 197 patients took statins for <1 month (m) or did not take any statin before admission (CHD1 group), while 204 patients took statins for ≥1 m before admission (CHD2 group). Blood lipid levels were measured at 0, 2, and 4 h after a daily breakfast. Non-fasting LDL-C and non-HDL-C levels significantly decreased after a daily meal (P < 0.05). Both fasting and non-fasting LDL-C or non-HDL-C levels were significantly lower in the CHD2 group. The percentage attainment of LDL-C <1.4 mmol/L at 2 and 4 h after a daily breakfast was significantly higher than that during fasting (P < 0.05), but the percent attainment of non-fasting non-HDL-C <2.2 mmol/L was close to its fasting value (P > 0.05). Analysis of c-statistic showed that non-fasting cut-off points for LDL-C and non-HDL-C were 1.19 and 2.11 mmol/L, corresponding to their fasting goal levels of 1.4 and 2.2 mmol/L, respectively. When post-prandial LDL-C and non-HDL-C goal attainments were re-evaluated using non-fasting cut-off points, there were no significant differences in percentage attainment between fasting and non-fasting states. Non-HDL-C is more stable than LDL-C in assessing the percent attainment of non-fasting lipid for coronary heart disease patients. If we want to use LDL-C to assess the percent attainment of post-prandial blood lipids, we may need to determine a lower non-fasting cut-off point.

Non-HDL-C/TG ratio indicates significant underestimation of calculated low-density lipoprotein cholesterol (LDL-C) better than TG level: a study on the reliability of mathematical formulas used for LDL-C estimation

OBJECTIVES

Low-density lipoprotein cholesterol (LDL-C) is the main laboratory parameter used for the management of cardiovascular disease. The aim of this study was to compare measured LDL-C with LDL-C as calculated by the Friedewald, Martin/Hopkins, Vujovic, and Sampson formulas with regard to triglyceride (TG), LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C)/TG ratio.

METHODS

The 1,209 calculated LDL-C results were compared with LDL-C measured using ultracentrifugation-precipitation (first study) and direct (second study) methods. The Passing-Bablok regression was applied to compare the methods. The percentage difference between calculated and measured LDL-C (total error) and the number of results exceeding the total error goal of 12% were established.

RESULTS

There was good correlation between the measurement and calculation methods (r 0.962-0.985). The median total error ranged from -2.7%/+1.4% (first/second study) for Vujovic formula to -6.7%/-4.3% for Friedewald formula. The numbers of underestimated results exceeding the total error goal of 12% were 67 (Vujovic), 134 (Martin/Hopkins), 157 (Samspon), and 239 (Friedewald). Less than 7% of those results were obtained for samples with TG >4.5 mmol/L. From 57% (Martin/Hopkins) to 81% (Vujovic) of underestimated results were obtained for samples with a non-HDL-C/TG ratio of <2.4.

CONCLUSIONS

The Martin/Hopkins, Vujovic and Sampson formulas appear to be more accurate than the Friedewald formula. To minimize the number of significantly underestimated LDL-C results, we propose the implementation of risk categories according to non-HDL-C/TG ratio and suggest that for samples with a non-HDL-C/TG ratio of <1.2, the LDL-C level should not be calculated but measured independently from TG level.

Nuclear magnetic resonance reveals postprandial low-density lipoprotein cholesterol determined by enzymatic method could be a misleading indicator

BACKGROUND

Serum concentration of low-density lipoprotein cholesterol (LDL-C) is markedly reduced after a meal. Does postprandial cholesterol in LDL truly decline via clearance of LDL particles or is there simply a redistribution of cholesterol in LDL subclasses? Thus, we sought to evaluate whether postprandial decline of LDL-C reflects a reduction of LDL particle and to assess the correlation between proprotein convertase subtilisin/kexin type 9 (PCSK9) concentration and postprandial atherogenic lipoproteins profile.

METHODS

Eighty-seven persons were enrolled in this study. We measured lipid profiles by enzymatic and nuclear magnetic resonance (NMR)-based methods and serum PCSK9 concentration by enzyme-linked immunosorbent assays before and after a meal. Plasma samples were collected after a 10-h fasting and 2 and 4 h post-meal.

RESULTS

Compared to the fasting status, there was significant postprandial decline of LDL-C measured enzymatically (LDL-Ce) at 2nd and 4th h [99.38 (80.43, 120.65) vs 95.51 (74.25, 117.17) vs 87.01 (69.99, 108.28) mg/dl, p < 0.000]. But there was no significant reduction in LDL particle and its cholesterol content (LDL-Cn) determined by NMR. Just the postprandial large LDL particle [186.45 (151.36, 229.42) vs 176.92 (147.43, 220.91) vs 181.77 (149.05, 224.17), p < 0.000] and its cholesterol content [19.10 (15.09, 22.37) vs 18.28 (14.59, 21.84) vs 17.79 (14.62, 22.14), p < 0.000] were greatly decreased at 2nd and 4th h compared to the fasting one. Interestingly, postprandial serum PCSK9 was decreased at 2nd and 4th h compared with fasting concentration [298.75 (233.25, 396.92) vs 257.34 (207.52, 342.36) vs 250.57 (215.02, 339.66) ng/ml, p < 0.000]. The postprandial percent decrease in serum PCSK9 at 4th h was positively correlated to the percent decline in postprandial LDL-Ce (r = 0.252, p = 0.019) but was independently associated with the percent increase in remnant cholesterol (r = 0.262, p = 0.016).

CONCLUSIONS

Postprandial decline of LDL-C determined enzymatically was not confirmed by NMR-based methods. Indeed, there exists cholesterol redistribution in LDL subclasses following a meal. The decrease of postprandial PCSK9 may be secondary to the increase in intrahepatic lipids following food intake.

Determination of optimal cut-off points after a high-fat meal corresponding to fasting elevations of triglyceride and remnant cholesterol in Chinese subjects

BACKGROUND

Postprandial high triglyceride (HTG), marking elevated level of remnant cholesterol (RC), is an independent risk factor of coronary heart disease (CHD). The postprandial cut-off points for HTG and high RC (HRC) after a daily meal are recommended as 2.0 mmol/L and 0.9 mmol/L, respectively, by the European Atherosclerosis Society (EAS), while those after a high-fat meal in Chinese subjects were not explored.

METHODS

Ninety subjects, including 60 CHD patients (CHD group) and 30 non-CHD controls (CON group), were enrolled in this study. Serum levels of blood lipids, including calculated RC, were monitored at 0, 2, 4 and 6 h after a high-fat meal with 800 kcal and 50 g fat. Analysis of c-statistic was used to determine the cut-off points for postprandial HTG and HRC.

RESULTS

Postprandial levels of triglyceride (TG) and RC significantly increased and peaked at 4 h after a high-fat meal in two groups, although those in CHD group were significantly higher (P < 0.05). The optimal cut-off point to predict HTG at 4 h corresponding to fasting TG ≥ 1.7 mmol/L was 3.12 mmol/L, and that to predict HRC at 4 h corresponding to fasting RC ≥ 0.8 mmol/L was 1.36 mmol/L. According to the new cut-off points, the omissive diagnosis rates of postprandial HTG and HRC decreased obviously.

CONCLUSION

The cut-off points of postprandial HTG and HRC in Chinese subjects after a high-fat meal were higher than those after a daily meal recommended by the EAS, indicating that specific cut-off points should be determined after a certain high-fat meal.