Age- and sex-specific reference values for non-HDL cholesterol and remnant cholesterol derived from the Nordic Reference Interval Project (NORIP)

Reference Interval for Non-HDL-Cholesterol, Remnant Cholesterol and Other Lipid Parameters in the Southern Iranian Population; Findings From Bandare Kong and Fasa Cohort Studies

BACKGROUND

Growing evidence shows the undisputable role of non-HDL-C and remnant cholesterol (remnant-C) in cardiovascular disease (CVD) risk assessment and treatment. However, the reference interval (RI) for these lipid parameters is not readily available. The aim of the present investigation was to determine the age and sex-specific RIs for non-HDL-C and remnant-C as well as other lipid parameters among a healthy population in southern Iran. We also report the RI of lipid parameters in rural and urban residents, smokers and post-menopausal women.

METHODS

Among 14063 participants of Bandare Kong and Fasa cohort studies, 792 healthy subjects (205 men and 578 women) aged 35-70 years were selected. Fasting blood samples were used for determination of total cholesterol (TC), triglycerides (TG) and HDL-C using colorimetric methods. Non-HDL-C and remnant-C were calculated using the valid formula. The 2.5th and 97.5th percentiles were calculated and considered as RI.

RESULTS

In the total population (n=792, age 35-70), RIs for non-HDL-C and remnant-C was 74.0-206.8 and 8.0-52.7 mg/dL, respectively. Age (35-44 and≥45 years) and gender-specific RIs for serum non-HDL-C and remnant-C were determined. Remnant-C and non-HDL-C level were different between sex and age categories. The mean value of all lipid parameters except HDL-C was higher in men, urban residents, subject with age≥45 years and smokers.

CONCLUSION

This is the first study in which the RIs for non-HDL-C and remnant-C in southern Iran are reported. This may help physicians to conveniently use these lipid parameters for patient care and better cardiovascular risk assessment.

Effects of Seven Weeks of Combined Physical Training on High-Density Lipoprotein Functionality in Overweight/Obese Subjects

Our study aimed to investigate the effects of exercise on HDL composition and functional properties in overweight/obese subjects. Eighteen overweight/obese subjects (nine F and nine M, BMI = 30.3 ± 3 kg/m2) attended supervised training for 7 weeks. The protocol included combined resistance and conditioning training four to five times each week. The activity of the antioxidant enzyme paraoxonase-1 (PON1) associated with HDL was evaluated in all subjects before and after the training intervention. Moreover, myeloperoxidase (MPO) levels and oxidative stress markers (ox-LDLs and total antioxidant capacity) were studied in the serums of the subjects. At the end of the intervention, the activity of PON1 was increased (p < 0.0001), and MPO levels and the MPO/PON1 ratio were decreased (p < 0.0001). In addition, a significant improvement in muscle strength and maximal oxygen uptake (VO2max) (p < 0.0001) and a significant reduction in total and visceral adipose tissue mass (p < 0.001) and waist circumference (p < 0.008), without any significant decrease in body weight, were observed. A significant correlation was established between serum MPO/PON ratios, HDL redox activity and ox-LDLs. In conclusion, our results demonstrate that exercise training, without modifications of dietary habits, improved HDL functionality in overweight/obese adults, without any significant reduction in BMI or modifications of glucose and lipid biochemical parameters.

Intrapartum Factors Affecting Abnormal Lipid Profiles in Early Postpartum Period

The aim of this research is to investigate the risk factors during pregnancy affect abnormal lipid profiles in women with early postpartum period. This was a single-center retrospective study including 869 women who delivered between December 2017 and May 2019. We collected total cholesterol levels, both at 24–28 GWs and 1 month before delivery. Lipid profiles such as total cholesterol, high-density lipoprotein (HDL), triglyceride (TG) and low-density lipoprotein (LDL) at 6 weeks after delivery were retrieved. Subjects were categorized into 3 groups such as normal, borderline and abnormal group according to the lipid profile levels. The risk factors associated with borderline to abnormal HDL level were body mass index (BMI) of pre-pregnancy (OR = 1.182, 95% CI: 1.116–1.252, p < 0.001), weight gain during pregnancy (OR = 1.085, 95% CI: 1.042–1.131, p < 0.001) and hypertension (HTN) (OR = 3.451, 95% CI: 1.224–9.727, p = 0.02). The risk factors associated with borderline or abnormal TG were BMI of pre-pregnancy, weight gain during pregnancy and weight reduction after delivery. HTN was associated with borderline to abnormal TG in postpartum (OR = 2.891, 95% CI: 1.168–7.156, p = 0.02), while GDM correlated purely with abnormal TG in postpartum (OR = 2.453, 95% CI: 1.068–5.630, p = 0.03). Abnormal lipid profiles in postpartum were significantly associated with BMI of pre-pregnancy, weight gain during pregnancy and weight reduction after delivery. In addition, pregnancy-related HTN was highly associated with abnormal HDL level, and GDM was associated with abnormal TG level in the early postpartum period.

Age-and sex-specific reference intervals of total cholesterol, LDL cholesterol, HDL cholesterol and non-HDL cholesterol. Comparison of two algorithms for the indirect estimation of reference intervals

Objectives

Reference intervals of total cholesterol concentrations in plasma and of their fractions low-density lipoprotein (LDL)-, high-density lipoprotein (HDL)-and non-HDL concentrations are seldom studied with respect to the relevance of age and sex. Therefore, the effect of age and sex on the reference intervals was reinvestigated with 2 indirect procedures.

Methods

As an indirect approach, the truncated minimum chi-square method was applied. All analyses were performed by computer programs available. The script published on the homepage of the German Society of Clinical Chemistry and Laboratory Medicine (DGKL) allows to derive a continuous age dependency of reference intervals together with their confidence and equivalence limits. The results of this approach were compared with those obtained by an indirect method developed more recently, the refineR algorithm.

Results

In the present study, the upper reference limits of total cholesterol varied from 5.1 to 7.8 mmol/L (197–302 mg/dL) depending on various biological variables (as age, sex, inpatients versus outpatients). These upper limits increased with age. Differences between sexes can be neglected except for the age above 80 years. The pattern of reference limits of LDL cholesterol and non-HDL cholesterol paralleled those of total cholesterol. The reference limits of HDL cholesterol were higher in women than in men but were independent of age.

Conclusions

Reference limits for the concentrations of total cholesterol and their fractions LDL-, HDL-and non-HDL concentrations should be stratified for age and sex.

Reduced Sensitivity to Thyroid Hormones Is Associated With High Remnant Cholesterol Levels in Chinese Euthyroid Adults

CONTEXT

It remains unclear whether the thyroid system could regulate the atherogenic remnant cholesterol (RC) levels in euthyroid status.

OBJECTIVE

We aimed to investigate the relationship between sensitivity to thyroid hormones and RC levels in Chinese euthyroid population.

METHODS

This study included 18 766 euthyroid adults. High RC levels were defined as the upper quartile of RC levels. The thyroid hormone sensitivity indices, including thyroid feedback quantile-based index (TFQI), thyroid-stimulating hormone index (TSHI), thyrotrophic thyroxine resistance index (TT4RI), and free triiodothyronine to free thyroxine (FT3/FT4) ratio were calculated. Linear and binary logistic regression analysis were applied to determine the associations between those composite indices with RC levels by genders.

RESULTS

Both females and males with high RC levels exhibited co-existing higher TSH and FT4 levels. Linear regression analysis revealed that TFQI, TSHI, and TT4RI were positively, while FT3/FT4 ratio levels were negatively associated with serum RC levels. The odds ratios (ORs) (95% CI) for high RC levels were increased with rising TFQI quartiles (Q) [females: Q3 1.41 (1.22-1.63), Q4 1.61 (1.39-1.86); males: Q3 1.25 (1.09-1.45), Q4 1.38 (1.19-1.59), all P for trend < 0.001] after full adjustment, with Q1 as the reference. TSHI and TT4RI yielded similar results. By contrast, the ORs (95% CI) for high RC levels were decreased with increasing FT3/FT4 ratio quartiles in both genders (P for trend < 0.001).

CONCLUSION

In euthyroid adults, reduced sensitivity to thyroid hormones was associated with high RC levels. Our results suggested an additive cardiometabolic risk of euthyroid population with thyroid hormones insensitivity.

Concentrations of nine endogenous steroid hormones in 70-year-old men and women

OBJECTIVES

Circulating concentrations of endogenous steroids have systemic implications on health in elderly. However, population-based age- and ethnicity-specific data are scarce. The aim was to report sex-specific plasma concentrations of endogenous sex and adrenal steroids in elderly Swedish Caucasians, to examine the impact of BMI and to present concentrations in apparently healthy subjects.

METHODS

A population-based observational study of 70-year olds, including 684 community-dwelling men and women enrolled in the PIVUS study, Sweden. Median plasma concentrations were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for pregnenolone, 17-hydroxypregnenolone, 17-hydroxy-progesterone, 11-deoxycortisol, DHEA, androstenedione, testosterone, estrone and estradiol.

RESULTS

Plasma concentrations were significantly higher in men (n = 452) than in women (n = 232) for estradiol: median 61.3 pmol/L (95% CI, 11.4, 142.7) vs 18.4 (4.0, 127.3), for estrone: 92.8 (33.3, 206) vs 71.6 (17.8, 209) pmol/L, and for testosterone 13.8 (5.7, 28.0) vs 0.7 (0.2, 2.0) nmol/L. Higher concentrations of estrone and estradiol were observed in obese than non-obese women. Compared to non-obese men, obese men had lower concentrations of testosterone and its precursors: 17-hydroxypregnenolone, 17-hydroxyprogesterone, androstenedione and DHEA. The subgroup of apparently healthy individuals had median values > 20% lower for estrone and estradiol in women but slightly higher for testosterone in both sexes.

CONCLUSIONS

Concentrations of estradiol, estrone and testosterone were higher in 70-year-old men than in women. BMI associated positively to estradiol and estrone in women and negatively to testosterone in men. Apparently healthy women had lower median concentrations of estradiol and estrone and men had higher median testosterone compared to all individuals.

Variations in biomarkers of dyslipidemia and dysbiosis during the menstrual cycle: a pilot study in healthy volunteers

BACKGROUND

Dyslipidemia in metabolic syndrome may introduce an underestimation of the risk for cardiovascular disease (CVD) using Low-Density Lipoprotein-Cholesterol (LDL-C) as a surrogate marker. Recently, non-High-Density Lipoprotein-Cholesterol (non-HDL-C), Apolipoprotein B (ApoB) and remnant-Cholesterol (remnant-C) have been suggested as better biomarkers for dyslipidemia. In addition, the microbial metabolites trimethylamine-N-oxide (TMAO), betaine and choline have been associated with CVD and suggested as markers for dysbiosis. There is a lack of knowledge on potential alterations in these biomarkers during the menstrual cycle. The aim of this single center, prospective non-interventional study, was to investigate variations in biomarkers of dyslipidemia and dysbiosis in healthy volunteers during the menstrual cycle.

METHOD

Serum samples were collected from 17 healthy, regularly menstruating women during two menstrual cycles, including the follicular, ovulatory and luteal phases. Levels of lipoproteins, lipoprotein ratios and microbial metabolites were analyzed in a total of 90 samples (30 complete menstrual cycles).

RESULTS

ApoB, ApoB/HDL and non-HDL-C/HDL ratios were significantly higher in the follicular phase compared to the ovulatory and luteal phases (p < 0.05). Remnant-C were higher during the luteal phase (p < 0.05). TMAO did not vary during the different phases and did not correlate with estrogen levels.

CONCLUSION

Our data support that biomarkers for dyslipidemia vary during the menstrual cycle. Thus, to avoid an underestimation of cardiovascular risk, sampling during the follicular phase, when levels of pro-atherogenic lipids are higher, may be considered.

A study on the correlation between remnant cholesterol and urinary albumin to creatinine ratio in Chinese community adults: A report from the REACTION study

BACKGROUND

The correlation between remnant cholesterol (RC) and urinary albumin to creatinine ratio (UACR) has not been illustrated. The present study aims to explore the correlation between RC levels and UACR in Chinese community adults.

METHODS

This study included 35 848 participants from a cohort study (REACTION). The UACR data were divided into three groups: UACR <10 mg/g, 10 ≤UACR<30 mg/g, and UACR ≥30 mg/g groups. RC was divided into two groups, according to the 75th percentile: <75% group and ≥75% group. Multiple logistic regression analysis was used to evaluate the correlation between RC and UACR.

RESULTS

The RC exhibited an adjusted odds ratio that was significant in models 1-5. Although all confounders were corrected in model 5, RC and UACR were still significantly correlated， and the correlation was more significant in females，when compared to males (odds ratio [OR]: 1.117, 95% CI: 1.063-1.176, P < 0.001 for all subjects; OR: 1.092, 95% CI: 1.128-1.161, P = 0.004 for females; and OR: 1.085, 95% CI: 0.998-1.194, P = 0.088 for males). The RC was significantly correlated with UACR for subjects with 5.6 ≤ fasting blood glucose < 7.0 or 7.8 ≤ post-load blood glucose < 11.1 mmol/L, 24 ≤ body mass index (BMI) < 28 kg/m² , 120 ≤ systolic blood pressure < 140 and/or 80 ≤ diastolic blood pressure < 90 mm Hg.

CONCLUSIONS

In the Chinese community, RC is highly correlated with UACR, and the correlation is more significant in females compared with males. At higher RC levels, patients with critical values of blood pressure, BMI and blood glucose have a more significant correlation between RC and UACR.