Background: Obesity markers, the lipid accumulation product (LAP), visceral adiposity index (VAI), triglyceride and glucose (TyG) index, and waist-to-height ratio (WHtR) are useful for assessing the risk of obesity-related cardiovascular disease. However, no previous study has assessed the usefulness of these four indices as predictors of metabolic syndrome among middle-aged and older Korean populations. Purpose: To investigate the usefulness of LAP, VAI, TyG index, and WHtR as predictors of metabolic syndrome in middle-aged and older Korean populations. Methods: This study included 15,490 male and female adults aged 40 years or older who underwent a medical check-up in a general hospital located in a Korean metropolitan area between January 2015 and December 2016. The diagnostic criteria for metabolic syndrome suggested by the American Heart Association/National Heart Lung and Blood Institute were used. LAP, VAI, and TyG index were computed based on the suggested mathematical models. WHtR was computed by dividing waist circumference by height. The independent sample t-test, one-way analysis of variance, Scheffe test, chi-square test, Pearson’s correlation analysis, and logistic regression were used to analyze the data. Results: LAP, VAI, TyG index, and WHtR were significantly related to metabolic syndrome in both sexes. Receiver operating characteristic curve analysis showed the following optimal cutoffs for LAP, VAI, TyG index, and WHtR: 33.97, 1.84, 8.81, and 0.51, respectively. After adjusting for latent confounding variables (age, systolic blood pressure, diastolic blood pressure, and waist circumference), LAP, VAI, TyG index, and WHtR were significantly correlated with metabolic syndrome. Area under the curve (AUC) values based on ROC curves showed that LAP, VAI, TyG index, and WHtR were reliable predictors of metabolic syndrome. LAP had the greatest AUC, suggesting that it was a more useful predictor than the other markers (AUC=0.917, 95% confidence interval: 0.913–0.922). Conclusion: LAP, VAI, TyG index, and WHtR are useful predictors of metabolic syndrome in middle-aged and older Koreans, but LAP had the greatest diagnostic accuracy.

Thyroid dysfunction increases the prevalence of metabolic syndrome. However, the link between thyroid hormones and metabolic syndrome remains debatable, and the effect of sex on their relationship is not completely understood. To elucidate the relationship of thyroid hormones with metabolic syndrome and its components according to sex in euthyroid individuals in South Korea. Adult participants who underwent thyroid tests at our institution between January 2015 and December 2018 and had thyroid-stimulating hormone (TSH; 0.270–4.200 μIU/mL) and free thyroxine (FT4; 0.93–1.70 ng/dL) levels in the normal range were included. After correcting for age and body mass index, multiple linear regression was performed to assess the association of TSH and FT4 with metabolic syndrome and its components, and logistic regression was performed to estimate the risk of developing metabolic syndrome and its components according to different thyroid hormone quartiles. We included 12,478 men and 7,575 women in this study. The prevalence of metabolic syndrome was 9.68%. In men, TSH was positively associated with blood pressure and triglycerides, and the odds ratio for high blood pressure and hypertriglyceridemia was approximately 1.3 times higher in the fourth quartile than in the first quartile. FT4 associated positively with waist circumference, and a high odds ratio for abdominal obesity in the fourth quartile was observed in both men (odds ratio [OR], 1.239; 95% confidence interval [CI], 1.045–1.470) and women (OR, 1.302; 95% CI, 1.029–1.649). A negative association was found between FT4 and triglycerides, and concurrently, the odds ratios for hypertriglyceridemia were lower in the fourth quartile in both men (OR, 0.692; 95% CI, 0.619–0.774) and women (OR: 0.641; 95% CI: 0.512–0.803). In addition, a higher odds ratio for high blood pressure was observed in the fourth quartiles of FT4 and TSH in women. However, there was no association between TSH and FT4 levels and the onset of metabolic syndrome in either of the sexes. Serum TSH and FT4 levels were associated with different metabolic syndrome components in men and women, but there was no association with the onset of metabolic syndrome.

Purpose: The visceral adiposity index (VAI) and lipid accumulation product (LAP) are useful for assessing visceral obesity. However, these indices were developed for Caucasians, and it is necessary to confirm whether the VAI and LAP are appropriate indicators for identifying obesity phenotypes in Asians. This study investigated whether the VAI and LAP are effective indicators for diagnosing four obesity phenotypes in South Korean adults. Patients and Methods: This cross-sectional study enrolled 23,310 adult participants (age ≥ 20 years) who had undergone a health checkup at a general hospital in Gyeonggi-do, South Korea from January 2017 to December 2020. VAI and LAP were calculated based on the presented mathematical model according to sex. According to the metabolic health status and presence or absence of obesity, the obesity phenotypes were classified into 4 groups: metabolically healthy non-obese (N=14,240, 61.1%), metabolically unhealthy non-obese (N=477, 2.0%), metabolically healthy obese (MHO; N=6796, 29.2%), and metabolically unhealthy obesity (MUO; N=1797, 7.7%). Results: The receiver operating characteristics curve analysis showed VAI best predicted MUO among the four obesity phenotypes, whereas the LAP showed excellent discriminating ability for the MUO group (area under the curve 0.877, 0.849, and 0.921 and 0.923, 0.907, and 0.954 for all participants, men, and women, respectively). The optimal VAI cutoff values for identifying the MUO group were 1.83 in men and 1.58 in women, and the optimal cutoff values for the LAP were 41.45 in men and 23.83 in women, with a higher value for men. After adjusting for potential confounding factors, the VAI and LAP were associated with an increased risk in the MHO and MUO groups among the obesity phenotypes in both sexes. Conclusion: In South Korean adults, the VAI and LAP are closely related to the MUO phenotype in both sexes and are effective indices for predicting the MUO phenotype.

To investigate changes of cardiac and muscle damage markers in exercise-induced hypertension (EIH) runners before running (pre-race), immediately after completing a 100-km ultramarathon race, and during the recovery period (24, 72, and 120 hours post-race). In this observational study, volunteers were divided into EIH group (n=11) whose maximum systolic blood pressure was ≥210 mmHg in graded exercise testing and normal exercise blood pressure response (NEBPR) group (n=11). Their blood samples were collected at pre-race, immediately after race, and at 24, 72, and 120 hours post-race. Creatine kinase (CK) and cardiac troponin I (cTnI) levels were significantly higher in EIH group than those in the NEBPR group immediately after race and at 24 hours post-race (all p<0.05). However, lactate dehydrogenase (LDH), creatine kinase-myocardial band (CKMB), or CKMB/CK levels did not show any significant differences between the two groups in each period. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were significantly higher in EIH group than those in NEBPR group immediately after race and at 24 and 72 hours postrace (all p<0.05). A high sensitivity C-reactive protein (hs-CRP) level was significantly higher in EIH group than that in NEBPR group at 24 hours post-race (p<0.05). The phenomenon of higher inflammatory and cardiac marker levels in EIH group may exaggerate cardiac volume pressure and blood flow restrictions which in turn can result in cardiac muscle damage. Further prospective studies are needed to investigate the chronic effect of such phenomenon on the cardiovascular system in EIH runners.

Seung Bok Hong, Kyung-A Shin. Korean J Clin Lab Sci. 2018;50:245-52. https://doi.org/10.15324/kjcls.2018.50.3.245

Kyung-A Shin. Korean J Clin Lab Sci. 2017;49:121-7. https://doi.org/10.15324/kjcls.2017.49.2.121