Association between serum uric acid level and metabolic syndrome

Uric acid and metabolic syndrome: Importance of hyperuricemia cut-off

BACKGROUND

The relationship between HyperUricemia (HU) and Metabolic Sindrome (MS) and if Uric Acid (UA) should be inserted into MS definitions is a matter of debate. Aim of our study was to evaluate the correlation between UA and HU with Insulin Resistance (IR) and MS in a population of hypertensive patients. HU was defined with two cut-offs (the classic one of ≥6 mg/dL for women and ≥ 7 for men; the newly proposed URRAH one with ≥5.6 mg/dL for both sexes).

METHODS

We enrolled 473 Hypertensive patients followed by the Hypertension Unit of San Gerardo Hospital (Monza, Italy). IR was defined through TG/HDL ratio and NCEP-ATP-III criteria were used for MS diagnosis.

RESULTS

MS was found in 33.6 % while HU affected 14.8 % of subjects according to the traditional cut-off and 35.9 % with the URRAH cut-off. 9.7 % (traditional cut-off) and 17.3 % (URRAH's threshold) of the subjects had both HU and MS. UA level was significantly higher in MS group (5.7 vs 4.9 mg/dL, p < 0.0001) as well as for HU (29.0 vs 7.6 % and 51.6 vs 28.0 %, for classic and URRAH cut-off respectively, p < 0.0001 for both comparison). Logistic multivariable regression models showed that UA is related to MS diagnosis (OR = 1.608 for each 1 mg/dL), as well as HU with both cut-off (OR = 5.532 and OR = 3.379, p < 0.0001 for all comparison, for the classic cut-off and the URRAH one respectively).

CONCLUSIONS

The main finding of our study is that UA and HU significantly relate to IR and MS. The higher the values of UA and the higher the cut-off used, the higher the strength of the relationship.

Association of hyperuricemia with metabolic syndrome and its components in an adult population of Faisalabad, Pakistan

BACKGROUND AND AIMS

The rising prevalence of metabolic syndrome (MetS) is a matter of serious concern worldwide. Hyperuricemia has been observed as an independent risk factor in the development of MetS and each of its individual components in different populations. This study aims to determine the association of hyperuricemia with MetS and its individual components in a Pakistani cohort.

METHODS AND RESULTS

A cross-sectional study was performed in a public sector hospital in Faisalabad, Pakistan. Total 204 participants were studied along with their anthropometric measurements and blood sample analysis for clinically important parameters. MetS was defined according to the NCEP-criteria. Independent sample t-test, Binomial logistic regression and Linear regression analyses were used to determine the association between hyperuricemia and metabolic syndrome. The prevalence of MetS and hyperuricemia in our study was 42.6% and 31.9% respectively. As compared to the normo-uricemic group, the hyperuricemic group had a significantly higher systolic blood pressure, BMI and lower HDL-C level (p < 0.05). After adjusting for age, gender, BMI and LDL-C, hyperuricemia was observed to increase the risk of MetS, increased systolic blood pressure and reduce HDL-C respectively by 1.34, 1.23 and 1.20 folds respectively.

CONCLUSION

In this study, a significant association between hyperuricemia and metabolic syndrome, systolic hypertension, blood glucose and decreased HDL-C was observed.

Associations of triglyceride-glucose index with hyperuricemia among Royal Thai Army personnel

BACKGROUND

Hyperuricemia has placed an immense burden on the global healthcare system. Studies have discovered a close correlation between serum uric acid (SUA) and insulin resistance (IR). The objective of this investigation is to examine the association between the triglyceride-glucose (TyG) index, a simple surrogate for IR, and the presence of hyperuricemia.

METHODS

Between 2017 and 2021, an epidemiologic study was conducted on Royal Thai Army (RTA) personnel aged 35-60 years, involving a total of 231,286 participants. In the study, hyperuricemia was defined as a SUA level of 7 mg/dL and 6 mg/dL among male and female participants, respectively. Using linear regression analysis and logistic regression analysis, the association between the TyG index and SUA was determined.

RESULTS

A positive relationship was demonstrated between the TyG index and the SUA. Overall, SUA increased by 0.32 per unit of TyG index growth (95% CI: 0.31-0.32). In comparison with the first quartile, employees in the fourth TyG quartile had a greater likelihood of having hyperuricemia [adjusted odds ratio (AOR): 2.45, 95% CI: 2.38-2.52]. Effect modification by obesity on the association between the TyG index and SUA was observed (P-interaction < 0.001). Among individuals with obesity, compared with the first TyG index quartile, the AOR for hyperuricemia was 2.15 (95% CI: 2.06-2.25) and 2.14 (95% CI: 1.81-2.53) for the fourth quartile of the TyG index for males and females, respectively. However, for nonobese personnel, in comparison to the top quartile of the TyG index, the AOR for hyperuricemia was 2.73 (95% CI:2.61-2.84) and 5.03 (95% CI: 4.03-6.29) for the fourth quartile of the TyG index for males and females, respectively. Personnel in the fourth TyG index quartile revealed that the prevalence of hyperuricemia reached 44.2%.

CONCLUSION

A robust positive association between the TyG index and SUA was illustrated among active-duty RTA personnel. Obesity was identified as a modifier influencing this relationship. Furthermore, individuals in the fourth quarter of the TyG index, regardless of their obesity status, could be considered appropriate candidates for screening SUA levels.

Extract of Aster glehni ameliorates potassium oxonate-induced hyperuricemia by modulating renal urate transporters and renal inflammation by suppressing TLR4/MyD88 signaling

Recent studies suggest that Aster glehni extract (AGE) reduces hyperuricemia by preventing xanthine oxidase activity. However, its effect on renal urate transporters responsible for modulating urate excretion has not been examined. This study investigated whether AGE affects gene expressions of urate transporters using potassium oxonate (PO)-induced hyperuricemia rats. Furthermore, the underlying mechanisms of AGE were explored to ameliorate renal inflammation and injury by PO. AGE effectively restored PO-induced dysregulation of renal urate transporter 1 (URAT1), glucose transporter 9 (GLUT9), ATP-binding cassette transporter subfamily G member 2 (ABCG2), organic anion transporter 1 (OAT1), and organic cation transporter 1 (OCT1), resulting in increasing urate excretion. Additionally, AGE suppressed toll-like receptor 4/myeloid differentiation factor 88 (TLR4/MyD88) signaling, phosphorylation of nuclear factor kappa B (NF-κB), and renal production of IFN-γ, IL-1β, TNF-α, and IL-6. These results suggest that AGE may ameliorate PO-induced hyperuricemia by modulating renal transporters, and further renal inflammation via inhibiting the TLR4/MyD88/NF-κB signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01153-5.

Design, synthesis, and biological studies of dual URAT1 inhibitor and FXR agonist based on benzbromarone

With increased unhealthy dietary patterns and a sedentary lifestyle, the prevalence of hyperuricemia is growing rapidly, placing a tremendous burden on the public health system. Persistent hyperuricemia in extreme cases induces gout, gouty arthritis, and other metabolic diseases. Benzbromarone is a potent human urate transporter 1 (URAT1) inhibitor that is widely used as a uric acid-lowering drug. Recent studies indicated that benzbromarone can also activate farnesoid X receptor (FXR), whereas its agonistic activity on FXR is rather poor. Mounting evidence suggested that the etiology of gout is directly related to NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasomes, and FXR suppresses the expression of NLRP3 in various ways. Therefore, the dual URAT1 inhibitor and FXR agonist may exert synergistic effects on decreasing uric acid (UA) levels and inhibiting inflammation. To obtain a better dual URAT1 inhibitor and FXR agonist, we performed the structure-based drug design (SBDD) strategy to improve the FXR activation of benzbromarone by forming strong interactions with ARG331 in FXR binding pocket. All of these efforts lead to the identification of compound 4, which exerts better activity on FXR and uric acid-lowering effect than benzbromarone.

Dietary polyglycosylated anthocyanins, the smart option? A comprehensive review on their health benefits and technological applications

Over the years, anthocyanins have emerged as one of the most enthralling groups of natural phenolic compounds and more than 700 distinct structures have already been identified, illustrating the exceptional variety spread in nature. The interest raised around anthocyanins goes way beyond their visually appealing colors and their acknowledged structural and biological properties have fueled intensive research toward their application in different contexts. However, the high susceptibility of monoglycosylated anthocyanins to degradation under certain external conditions might compromise their application. In that regard, polyglycosylated anthocyanins (PGA) might offer an alternative to overcome this issue, owing to their peculiar structure and consequent less predisposition to degradation. The most recent scientific and technological findings concerning PGA and their food sources are thoroughly described and discussed in this comprehensive review. Different issues, including their physical-chemical characteristics, consumption, bioavailability, and biological relevance in the context of different pathologies, are covered in detail, along with the most relevant prospective technological applications. Due to their complex structure and acyl groups, most of the PGA exhibit an overall higher stability than the monoglycosylated ones. Their versatility allows them to act in a wide range of pathologies, either by acting directly in molecular pathways or by modulating the disease environment attributing an added value to their food sources. Their recent usage for technological applications has also been particularly successful in different industry fields including food and smart packaging or in solar energy production systems. Altogether, this review aims to put into perspective the current state and future research on PGA and their food sources.

High Prevalence of Prediabetes and Associated Risk Factors in Urban Areas of Pontianak, Indonesia: A Cross-Sectional Study

Uncontrolled prediabetes can develop into Type 2 Diabetes mellitus (T2DM). The incidence of T2DM among adults in Pontianak, Indonesia was reported remarkably high. Therefore, this study aimed to investigate the risk factors for prediabetes in adults living in urban areas of Pontianak, Indonesia. A cross-sectional study was conducted in 5 subdistricts of Pontianak. A total of 506 adults underwent screening to obtain subjects with fasting blood glucose (FBS) of ≤124 mg/dL and aged >30 years. Blood pressure and body mass index (BMI) were measured. Interview using a structured questionnaire were performed to obtain data on predictor variables (age, sex, education, income, health insurance, tobacco use, history of hypertension, gout, high cholesterol level, frequency of exercise per week, and diabetic education). The prevalence of prediabetes among subjects was significantly high (76.4%). Subjects were predominantly above 40 years, female, had low income, low education level, and had health insurance. About a third of the subjects had a history of hypertension, gout, and high cholesterol level, respectively. The exercise frequency was mostly less than 3 times/week, and the BMI was mainly classified as overweight and obese. The result of spearman's rho correlation showed that age (r = 0.146; p=0.022) and BMI (r = 0.130; p=0.041) significantly correlated with prediabetes incidence. Moreover, the chi-square analysis demonstrated that health insurance ownership (OR = 4.473; 95% CI 1.824-10.972; p ≤ 0.001), history of hypertension (OR = 3.096; 95% CI 1.542-6.218; p=0.001), and history of gout (OR = 2.419; 95% CI 1.148-5.099; p=0.018), were associated with prediabetes incidence. For all these significant risk predictors except BMI, the significant associations were found only among female subjects after specific sex analysis. Moreover, multivariate logistic regression showed that health insurance ownerships (OR = 5.956; 95% CI 2.256-15.661; p ≤ 0.001) and history of hypertension (OR = 3.257; 95% CI 1.451-7.311; p=0.004), and systolic blood pressure (OR = 2.141; 95% CI 1.092-4.196; p=0.027) were the risk factors for prediabetes. It is concluded that the prevalence of prediabetes is probably high especially among urban people in Pontianak, Indonesia. Health insurance ownership and hypertension may have an important role in prediabetes management. The risk factors might be different between male and female.

Can biomarkers be used to improve diagnosis and prediction of metabolic syndrome in childhood cancer survivors? A systematic review

Childhood cancer survivors (CCS) are at increased risk to develop metabolic syndrome (MetS), diabetes, and cardiovascular disease. Common criteria underestimate adiposity and possibly underdiagnose MetS, particularly after abdominal radiotherapy. A systematic literature review and meta-analysis on the diagnostic and predictive value of nine newer MetS related biomarkers (adiponectin, leptin, uric acid, hsCRP, TNF-alpha, IL-1, IL-6, apolipoprotein B (apoB), and lipoprotein(a) [lp(a)]) in survivors and adult non-cancer survivors was performed by searching PubMed and Embase. Evidence was summarized with GRADE after risk of bias evaluation (QUADAS-2/QUIPS). Eligible studies on promising biomarkers were pooled. We identified 175 general population and five CCS studies. In the general population, valuable predictive biomarkers are uric acid, adiponectin, hsCRP and apoB (high level of evidence), and leptin (moderate level of evidence). Valuable diagnostic biomarkers are hsCRP, adiponectin, uric acid, and leptin (low, low, moderate, and high level of evidence, respectively). Meta-analysis showed OR for hyperuricemia of 2.94 (age-/sex-adjusted), OR per unit uric acid increase of 1.086 (unadjusted), and AUC for hsCRP of 0.71 (unadjusted). Uric acid, adiponectin, hsCRP, leptin, and apoB can be alternative biomarkers in the screening setting for MetS in survivors, to enhance early identification of those at high risk of subsequent complications.

Identification of biomarkers of brown adipose tissue aging highlights the role of dysfunctional energy and nucleotide metabolism pathways

Brown adipose tissue function declines during aging and may contribute to the onset of metabolic disorders such as diabetes and obesity. Only limited understanding of the mechanisms leading to the metabolic impairment of brown adipocytes during aging exists. To this end, interscapular brown adipose tissue samples were collected from young and aged mice for quantification of differential gene expression and metabolite levels. To identify potential processes involved in brown adipocyte dysfunction, metabolite concentrations were correlated to aging and significantly changed candidates were subsequently integrated with a non-targeted proteomic dataset and gene expression analyses. Our results include novel age-dependent correlations of polar intermediates in brown adipose tissue. Identified metabolites clustered around three biochemical processes, specifically energy metabolism, nucleotide metabolism and vitamin metabolism. One mechanism of brown adipose tissue dysfunction may be linked to mast cell activity, and we identify increased histamine levels in aged brown fat as a potential biomarker. In addition, alterations of genes involved in synthesis and degradation of many metabolites were mainly observed in the mature brown adipocyte fraction as opposed to the stromal vascular fraction. These findings may provide novel insights on the molecular mechanisms contributing to the impaired thermogenesis of brown adipocytes during aging.

The association of serum uric acid with metabolic syndrome and its components-From a single-clinical centre in China

BACKGROUND AND OBJECTIVES

Increasing evidence suggests that uric acid (UA) levels may play a role in the MetS. The purpose of this study was the association of serum uric acid with metabolic syndrome and its components from a single-clinical centre in China.

SUBJECTS AND METHODS

We retrospectively analysed the physical examination information of patients at the Health Checkup Centre of the Beijing Friendship Hospital, Capital Medical University in 2018. MetS was defined as ≥3 of the risk factors according to the revised Harmonised criteria. Statistical analyses were performed using the SPSS statistical software package, version 22.0 (IBM Corporation, Armonk, NY, USA).

RESULTS

A total of 36 663 subjects were retrospectively analysed. The incidence of MetS was 23.6% amongst the study participants and 38.9% in subjects with HUA. The incidence of HUA was 33.3% in the MetS group. Higher SUA levels were correlated with an increased risk of having full MetS, hypertriglyceridemia and low HDL-C after adjustment (all P < .001 for the trend). Only in males higher SUA levels correlated with an increased risk of being overweight. Individuals with the highest quartile of SUA had no significant association with having HP in males, and a significant association between SUA levels and hypertension was only seen in the highest quartile of females. Males with the highest quartile of SUA (Q4) and females with the higher quartiles of SUA (Q3 and Q4) had no significant association with having hyperglycemia.

CONCLUSION

The incidence of HUA was increased in the MetS group consisting of Chinese patient subjects living in Beijing. SUA is strongly associated with full MetS as well as hypertriglyceridemia and low HDL-C. The relationship between HUA and an overweight BMI, HP and hyperglycemia varied by gender.

The association between serum uric acid level and the risk of cognitive impairment after ischemic stroke

Post-stroke cognitive impairment (PSCI) is a severe complication of stroke. Predicting PSCI is difficult because some risk factors for stroke, such as blood glucose level and blood pressure, are affected by many other elements. Although recent studies have shown that high serum uric acid (UA) levels are associated with cognitive dysfunction and may be a risk factor for PSCI, its impact remains unclear. Accordingly, the present study aimed to explore the association between serum UA level and PSCI. In total, 274 patients who experienced acute cerebral infarction, confirmed between January 2016 and December 2018, were enrolled. Baseline data and biological indicators were recorded. According to the Montreal Cognitive Assessment (MoCA) scores, patients were divided into two groups: PSCI and non-PSCI. Logistic regression analysis was used to determine possible risk factors for PSCI. Results demonstrated that serum UA levels were significantly higher in the PSCI group than in the non-PSCI group. Multivariable logistic analysis revealed that age, years of education, and UA level were independent risk factors for PSCI. PSCI patients were subdivided according to serum UA level: high and low. Hypertension history and homocysteine (Hcy) levels differed significantly between the high and low UA level groups. Further analysis revealed that a history of hypertension and Hcy demonstrated a certain correlation (r = 0.163, 0.162; P < 0.05), suggesting that serum UA level was an independent risk factor for PSCI. These findings indicate that serum UA level was correlated with PSCI in post-stroke patients and is anticipated to be used in clinical practice to reduce the incidence of PSCI.

Association of Serum Uric Acid with cardio-metabolic risk factors and metabolic syndrome in seafarers working on tankers

BACKGROUND

There is still controversy over the clinical interpretation of the association between metabolic syndrome (MetS) and serum uric acid (SUA) levels. Therefore, the aim of this study was to investigate the association of SUA levels with MetS and other cardio-metabolic risk factors (CMRF) in seafarers working on tankers.

METHODS

This cross-sectional study was conducted in 2015 and included 234 male seafarers working on tankers. The participants were divided into three groups based on the tertiles of SUA. The report from of the National Committee of Obesity was used to define the MetS. The relationship between SUA, CMRF and MetS adjusted for age, educational level, job history, shift work, smoking and BMI was assessed by logistic regression analysis.

RESULTS

The subjects were aged 36.0 ± 10.3 years (mean ± SD). A notable upward trend was observed in mean weight, body mass index (BMI), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL) and very low-density lipoprotein (VLDL) as tertiles of SUA increased (P < 0.001). In all models of the logistic regression analyses, the odds ratio (OR) of high TG for participants in the 3rd tertile of SUA was four times higher than that for participants in the 1st tertile of SUA (P < 0.001). The odds ratio of high TC and the SUA levels increased, so that the odds ratio of high TC for participants in the 2nd tertile was 2.47 (95% CI: 1.10-5.53) (P < 0.05) as compared with that for participants in the 1st tertile. Significant association was observed between MetS and the levels of SUA; 6.10 (95% CI: 1.77-20.94) (P < 0.05).

CONCLUSIONS

Findings revealed that SUA levels were associated with MetS, high TG and high TC. Therefore, it is recommended that clinical attention should be given to symptoms related to elevated SUA - being one of the most important remediable risk factors for MetS - in the annual medical examinations of seafarers.

Associations of Serum Uric Acid with Endogenous Cholesterol Synthesis Indices in Men with High Cardiometabolic Risk

Background: Patients with metabolic syndrome (MetS) have increased endogenous synthesis of cholesterol, together with lower level of intestinal cholesterol absorption. However, less is known about how individual metabolic disturbances linked to MetS correlate with dysregulated cholesterol homeostasis. Methods: We consecutively examined 178 probands (91 women/87 men) characterized by the presence of one or two components of MetS (group with an increased cardiometabolic risk [CMR]) and 42 healthy controls (24 men/18 women) of similar age, as well. In all probands, the surrogate markers for cholesterol biosynthesis (lathosterol) and absorption (campesterol and β-sitosterol) were measured by capillary gas chromatography. In CMR group, we performed multivariate regression analysis to assess the dependence of the parameters of cholesterol biosynthesis/absorption on components of MetS including serum uric acid (SUA), apolipoprotein B (apoB), and age. Results: In CMR group, higher lathosterol to total plasma cholesterol (TC) ratio (LCR) was influenced by gender (P = 0.05, analysis of covariance [ANCOVA] for age), whereas ratios of campesterol (β-sitosterol, respectively) to TC were lower in CMR group (P < 0.001 and P = 0.002, ANCOVA for age). In men, LCR was positively associated with SUA, apoB, and hypertension (all P < 0.05). Lathosterol to campesterol or β-sitosterol ratios were highly dependent on SUA (both P < 0.01), the former being dependent also on apoB (P < 0.01). In women, these parameters were only weakly dependent on SUA. Conclusions: These results show that the concentration of SUA in men of CMR group is associated with the indices of de novo cholesterol biosynthesis. This association is probably influenced by interaction of arterial hypertension and apoB levels with cholesterol homeostasis.

Novel urate transporter 1 (URAT1) inhibitors: a review of recent patent literature (2016-2019)

Introduction: Human urate transporter 1 (URAT1), which is an influx transporter protein, is located at the apical surface of renal tubular cells and presumed to be the major transporter responsible for the reabsorption of urate from blood. About 90% of patients develop hyperuricemia due to insufficient urate excretion; thus, it is important to develop URAT1 inhibitors that could enhance renal urate excretion by blocking the reabsorption of urate anion. Areas covered: In this review, the authors addressed the patent applications (2016-2019) about URAT1 inhibitors and some medicinal chemistry strategies employed in these patents. Expert opinion: Substituent decorating, bioisosterism, and scaffold hopping are three common medicinal chemistry strategies used in the discovery of URAT1 inhibitors. Meanwhile, the introduction of sulfonyl group into small molecules has become one of the important strategies for structural optimization of URAT1 inhibitors. Furthermore, developing drug candidates targeting both URAT1 and xanthine oxidase (XOD) has attracted lots of interest and attention.

Uric Acid Levels Correlate with Sensory Nerve Function in Healthy Subjects

BACKGROUND

High levels of uric acid (UA) are associated with various peripheral neuropathies. Furthermore, uric acid levels have been found to correlate with both the clinical and electrophysiological severity of diabetic sensorimotor polyneuropathy, mainly with sensory functions.

OBJECTIVES

To determine whether higher UA levels are associated negatively with nerve function in healthy subjects.

METHODS

A total of 126 healthy subjects recruited prospectively for another study were included. We extracted demographic data, body mass index (BMI), blood pressure, Toronto Clinical Neuropathy Score (TCNS), electrophysiological findings, vibration perception thresholds (VPT), and laboratory test results including UA, hemoglobin A1c (HbA1c), estimated glomerular filtration rate (eGFR), and lipid levels.

RESULTS

The mean age of the cohort was 56 ± 17 years with 56% females. Males had higher UA values compared with females. Univariate beta regression coefficient analysis between UA levels and demographic, clinical, electrophysiological, and laboratory findings showed significant positive correlations with male gender, components of the metabolic syndrome, and with VPT, while an inverse correlation was found with electrophysiological sensory parameters. A multivariate regression model showed positive correlations only with BMI, finger VPT, and triglycerides.

CONCLUSION

Higher UA levels correlate with lower sensory nerve function in healthy subjects, expanding the evidence of possible negative influence of UA on peripheral nerves, although a causative role has not yet established.

Production Inhibition and Excretion Promotion of Urate by Fucoidan from Laminaria japonica in Adenine-Induced Hyperuricemic Mice

This work aims to explore the amelioration of fucoidan on adenine-induced hyperuricemia and hepatorental damage. Adenine-induced hyperuricemic mice were administered with fucoidan, allopurinol and vehicle control respectively to compare the effects of the drugs. Serum uric acid, urea nitrogen, hepatorenal functions, activities of hepatic adenosine deaminase (ADA), xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and NF-κB p65 were assessed. As the serum uric acid, urea nitrogen, creatinine, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) data demonstrated, the adenine not only mediated hepatorenal function disorders, but also induced hyperuricemia in mice. Meanwhile, activities of hepatic ADA and XOD were markedly augmented by adenine, and the expression of URAT1 was promoted, which was conducive to the reabsorption of urate. However, exposure to fucoidan completely reversed those adenine-induced negative alternations in mice, and the activities of hepatic ADA and XOD were recovered to the normal level. It was obvious that hepatic and renal functions were protected by fucoidan treatment. The expression of URAT1 was returned to normal, resulting in an increase of renal urate excretion and consequent healing of adenine-induced hyperuricemia in mice. Expression and activation of NF-κB p65 was promoted in kidneys of adenine treated mice, but suppressed in kidneys of mice exposed to fucoidan from Laminaria japonica or allopurinol. In conclusion, the fucoidan is a potential therapeutic agent for the treatment of hyperuricemia through dual regulatory roles on inhibition of hepatic metabolism and promotion of renal excretion of urate.

The Association Between Metabolic Syndrome and Serum Concentrations of Micronutrients, Inflammation, and Oxidative Stress Outside of the Clinical Reference Ranges: A Cross-Sectional Study

BACKGROUND

Clinical reference ranges are often used to assess nutritional status, but whether having lower or higher than the current clinical reference range for micronutrients, inflammation, and oxidative stress is related to metabolic syndrome (MetS) is not known. Our objectives are to estimate the odds of having MetS outside of established clinical references, and to identify any effect modifications by sex have for these relationships.

METHODS

Data from the 2005 to 2006 National Health and Nutrition Examination Survey were used (≥20 years; N = 2049) with MetS defined utilizing the harmonized criteria from the Joint Interim Statement. The odds of having MetS in individuals with lower or higher than the clinical reference range for the serum concentrations of micronutrient antioxidants, inflammation, and oxidative stress were estimated following adjustments for age, sex, ethnicity, education, income, smoking, alcohol intake, recreational physical activity, and BMI.

RESULTS

Having lower than the clinical reference range for carotenoids and vitamin C [odds ratios (95% confidence interval): 1.37 (1.05-1.78) and 1.39 (1.01-1.90), respectively] was associated with significantly greater odds of MetS. By contrast, having higher than the clinical reference range for vitamins A and E, uric acid, and γ-glutamyl transferase (GGT) [2.10 (1.50-2.92), 2.36 (1.78-3.13), 2.65 (1.54-4.57), and 2.08 (1.61-2.69), respectively] was associated with higher odds of MetS, whereas higher levels of vitamins B12 were protective [0.64 (0.42-0.98]. Sex moderated these relationships for carotenoids, vitamin A, C, E, uric acid, C-reactive protein, and GGT.

CONCLUSIONS

Lower carotenoids and vitamin C and higher vitamins A and E, uric acid, and oxidative stress were associated with a greater likelihood of MetS, whereas higher vitamin B12 was protective. Further research is necessary to replicate these findings in a prospective setting to confirm the importance of the overall and sex-specific findings.

Baseline and changes in serum uric acid independently predict 11-year incidence of metabolic syndrome among community-dwelling women

INTRODUCTION

Metabolic syndrome (MetS) is associated with an increased risk of major cardiovascular events. In women, increased serum uric acid (SUA) levels are associated with MetS and its components. However, whether baseline and changes in SUA predict incidence of MetS and its components remains unclear.

METHODS

The subjects comprised 407 women aged 71 ± 8 years from a rural village. We have identified participants who underwent a similar examination 11 years ago, and examined the relationship between baseline and changes in SUA, and MetS based on the modified criteria of the National Cholesterol Education Program's Adult Treatment Panel (NCEP-ATP) III report.

RESULTS

Of these subjects, 83 (20.4%) women at baseline and 190 (46.7%) women at follow-up had MetS. Multiple linear regression analysis was performed to evaluate the contribution of each confounding factor for MetS; both baseline and changes in SUA as well as history of cardiovascular disease, low-density lipoprotein cholesterol, and estimated glomerular filtration ratio (eGFR) were independently and significantly associated with the number of MetS components during an 11-year follow-up. The adjusted odds ratios (ORs) (95% confidence interval) for incident MetS across tertiles of baseline SUA and changes in SUA were 1.00, 1.47 (0.82-2.65), and 3.11 (1.66-5.83), and 1.00, 1.88 (1.03-3.40), and 2.49 (1.38-4.47), respectively. In addition, the combined effect between increased baseline and changes in SUA was also a significant and independent determinant for the accumulation of MetS components (F = 20.29, p < 0.001). The ORs for incident MetS were significant only in subjects with age ≥ 55 years, decline in eGFR, and no baseline MetS.

CONCLUSIONS

These results suggested that combined assessment of baseline and changes in SUA levels provides increased information for incident MetS, independent of other confounding factors in community-dwelling women.

An association of smoking with serum urate and gout: A health paradox

BACKGROUND

The potential effect of cigarette smoking on levels of serum urate and risk of gout has been considered by a large number of studies, either as the primary variable of interest or as a covariate.

METHODS

Here we systematically review the published evidence relating to the relationship of smoking with serum urate, hyperuricaemia, and gout.

RESULTS

Many studies have reported that smoking reduces serum urate, however, the evidence has not been conclusive with other studies pointing to the opposite or no effect. It has also been suggested that smoking reduces the risk of gout, although there is some evidence to contradict this finding.

CONCLUSION

A consensus has yet to be reached as to the effect of smoking on serum urate levels and the risk of gout.

Association between Mean Corpuscular Hemoglobin Concentration and Future Depressive Symptoms in Women

Insufficient hemoglobin and depression share several symptoms and often occur in the same patients. Here, we sought to clarify their relationship by investigating two indices of oxygenation at the tissue level: mean corpuscular hemoglobin concentration (MCHC) and hemoglobin level. We hypothesized that MCHC would be more informative than hemoglobin levels. This prospective, longitudinal, community-based study included 337 participants (108 men and 229 women; age range, 38-87 years) who received evaluations of MCHC, hemoglobin levels and depressive symptom scores (DSS) during baseline and follow-up examinations, which were performed in 2008-2011 and 2010-2012, respectively. MCHC and hemoglobin levels were measured as part of complete blood counts, while DSS was evaluated using the Beck Depression Inventory. Associations were analyzed using linear regression. We found a statistically significant association between baseline MCHC and follow-up DSS (β = -0.69, p = 0.026), which remained statistically significant after controlling for potential confounders (β = -0.71, p = 0.011). Further, when we analyzed the relationship separately for men and women, we observed that it remained stable for women before (β = -1.00, p = 0.014) and after (β = -1.09, p = 0.003) adjusting for confounders. The stable association indicates that MCHC may be superior to hemoglobin level as a prognostic factor for future depressive symptoms in women. MCHC is easy to measure and low MCHC is usually treatable. Therefore, screening and intervention efforts could be targeted at women with low MCHC, who appear to have elevated risks of developing depressive symptoms.

Overweight modifies the longitudinal association between uric acid and some components of the metabolic syndrome: The Tromsø Study

BACKGROUND

Elevated uric acid (UA) is associated with the presence of the metabolic syndrome (MetS). In a prospective cohort study, we assessed whether baseline and longitudinal change in UA were risk factors for development of MetS and its individual components.

METHODS

We included 3087 women and 2996 men who had UA measured in the population based Tromsø Study 1994-95. The participants were stratified according to body mass index (BMI). Endpoints were MetS and each component of the syndrome after 7 years, according to the revised National Cholesterol Education Program's Adult Treatment Panel III (NCEP-ATP III) definition.

RESULTS

Multiple logistic regression analyses showed that higher baseline UA was associated with higher odds of developing elevated blood pressure in overweight subjects (BMI ≥ 25 kg/m(2), odds ratio [OR] per 59 μmol/L UA increase 1.44, 95 % confidence interval [CI] = 1.17-1.77, P = 0.001), but not in normal-weight subjects (BMI < 25 kg/m(2), P for interaction = 0.04). Overweight also modified the association between baseline UA and the development of elevated fasting glucose (P for interaction = 0.01). UA was a predictor of MetS in all subjects (OR per 59 μmol/L UA increase 1.29, 95 % CI 1.18-1.41, P < 0.001). Furthermore, longitudinal UA change was independently associated with the development of MetS in all subjects (OR per 59 μmol/L UA increase over 7 years 1.28, 95 % CI 1.16-1.42, P < 0.001).

CONCLUSION

Increased levels of baseline UA independently predicted development of elevated blood pressure and higher fasting glycemia in the overweight, but not the normal-weight subjects. Baseline UA and longitudinal increase in UA over 7 years was associated with the development of MetS in all subjects. Whether increased UA should be treated differently in normal-weight and overweight persons needs further study.

Serum uric acid: A strong and independent predictor of metabolic syndrome after adjusting for body composition

BACKGROUND

Some observational studies have suggested that serum uric acid (SUA) levels are one of the determinants of the metabolic syndrome (MetS). However, previous studies reported combined results for men and women after adjusting for sex and few studies take body composition into consideration. Therefore, we performed this sex-specific longitudinal study to investigate how baseline SUA levels influence incident MetS, including body composition as an adjusting factor in a large number of subjects.

METHODS

A total of 14,442 participants (8715 men and 5727 women) participating in a medical health check-up program without diagnosed MetS at baseline were enrolled. Separate analyses were performed for men and women including body composition as a confounding factor. Cox proportional hazards models were used to quantify independent associations between SUA levels and incident MetS.

RESULTS

During 63,940person-years of follow-up, there were 4215 (2974 men, 1241 women) incident cases of MetS between 2006 and 2012. After adjustments for age, systolic BP, diastolic BP, BMI, eGFR, smoking status, TG, LDL-C, HDL-C, fasting glucose, and proportion of fat-free mass (100-fat mass, %), the hazard ratios (HR) [95% confidence interval (CI)] for incident MetS comparing the second, the third, and the fourth quartiles to the first quartile of SUA levels were 0.862 (0.770-0.965), 1.102 (0.991-1.225), and 1.246 (1.121-1.385) in men (p for trend<0.001), and 1.045 (0.862-1.266), 1.251 (1.050-1.490), and 1.321 (1.109-1.574) in women (p for trend<0.001), respectively. As a continuous variable, in fully-adjusted models, the HRs (95% CI) for incident MetS associated with each increase of 1mg/dl of SUA levels were 1.094 (1.060-1.130) in men (p<0.001) and 1.148 (1.072-1.228) in women (p<0.001), respectively.

CONCLUSION

We demonstrated that SUA levels are strong and independent predictors of MetS. This relationship remained significant after full adjustments for multiple associated confounders including body composition in both men and women.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Antioxidative phytochemicals from Rhododendron oldhamii Maxim. leaf extracts reduce serum uric acid levels in potassium oxonate-induced hyperuricemic mice

Background

Some of the genus Rhododendron was used in traditional medicine for arthritis, acute and chronic bronchitis, asthma, pain, inflammation, rheumatism, hypertension and metabolic diseases and many species of the genus Rhododendron contain a large number of phenolic compounds and antioxidant properties that could be developed into pharmaceutical products.

Methods

In this study, the antioxidative phytochemicals of Rhododendron oldhamii Maxim. leaves were detected by an online HPLC–DPPH method. In addition, the anti-hyperuricemic effect of the active phytochemicals from R. oldhamii leaf extracts was investigated using potassium oxonate (PO)-induced acute hyperuricemia.

Results

Six phytochemicals, including (2R, 3R)-epicatechin (1), (2R, 3R)-taxifolin (2), (2R, 3R)-astilbin (3), hyposide (4), guaijaverin (5), and quercitrin (6), were isolated using the developed screening method. Of these, compounds 3, 4, 5, and 6 were found to be major bioactive phytochemicals, and their contents were determined to be 130.8 ± 10.9, 105.5 ± 8.5, 104.1 ± 4.7, and 108.6 ± 4.0 mg per gram of EtOAc fraction, respectively. In addition, the four major bioactive phytochemicals at the same dosage (100 mmol/kg) were administered to the abdominal cavity of potassium oxonate (PO)-induced hyperuricemic mice, and the serum uric acid level was measured after 3 h of administration. H&E staining showed that PO-induced kidney injury caused renal tubular epithelium nuclear condensation in the cortex areas or the appearance of numerous hyaline casts in the medulla areas; treatment with 100 mmol/kg of EtOAc fraction, (2R, 3R)-astilbin, hyposide, guaijaverin, and quercitrin significantly reduced kidney injury. In addition, the serum uric acid level was significantly suppressed by 54.1, 35.1, 56.3, 56.3, and 53.2 %, respectively, by the administrations of 100 mmol/kg EtOAc fraction and the derived major phytochemicals, (2R, 3R)-astilbin, hyposide, guaijaverin, and quercitrin, compared to the PO group. The administration of 10 mg/kg benzbromarone, a well-known uricosuric agent, significantly reduced the serum uric acid level by 45.5 % compared to the PO group.

Conclusion

The in vivo decrease in uric acid was consistent with free radical scavenging activity, indicating that the major phytochemicals of R. oldhamii leave extracts and the derived phytochemicals possess potent hypouricemic effects, and they could be potential candidates for new hypouricemic agents.

Serum uric acid: a new therapeutic target for nonalcoholic fatty liver disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is a major, worldwide public health problem. NAFLD is recognized as a major cause of liver-related morbidity and mortality. However, physicians are currently limited by available treatment options. Recently, numerous studies have reported a correlation between serum uric acid (SUA) and NAFLD with numerous clinical and experimental studies demonstrating a significant correlation. This review will focus on the role of SUA in the development of NAFLD and its potential role as a new target for therapeutic intervention.

AREAS COVERED

This review discusses SUA as a significant independent factor in the development of NAFLD. Moreover, we introduce the causal relationship between SUA, metabolic syndrome, and NAFLD. We discuss two major theories of insulin resistance and inflammasomes as potential explanations of the mechanistic link between SUA and NAFLD. In addition, we review current and emerging therapeutic medications to control appropriate SUA levels.

EXPERT OPINION

There is an urgent need to develop novel, safe and effective therapies for the growing NAFLD epidemic. Reduction of SUA may be a promising potential treatment for patients with NAFLD. Clinical studies are required to determine the therapeutic effect of attenuation of hyperuricemia in humans with NAFLD.

A possible role of serum uric acid as a marker of metabolic syndrome

BACKGROUND/AIMS

The association between serum uric acid (SUA) levels and metabolic syndrome (MetS) has recently been reported in several cross-sectional and longitudinal studies. We investigated SUA as a biomarker to predict future development of MetS in healthy Korean men without diabetes or hypertension and determined the optimal cut-off levels of SUA.

METHODS

A retrospective cohort study was conducted using data from healthy men who received a general health check-up in 2003. A total of 1809 participants free of MetS, diabetes and hypertension was enrolled. Participants were classified into three groups based on SUA levels: group 1 (<5.5 mg/dL), group 2 (5.5-6.9 mg/dL) and group 3 (≥7.0 mg/dL).

RESULTS

During 13,802 person-years of follow up, 127 participants developed MetS. After adjusting for multiple associated parameters, SUA was significantly associated with incident MetS (hazard ratios comparing groups 2 and 3 vs group 1, 2.45 and 3.47 respectively; P < 0.001). In receiver operating characteristic curve analysis, the optimal cut-off level for SUA to predict the development of MetS was 6.5 mg/dL.

CONCLUSION

Our results indicate that an increased level of SUA, even within the normal range, is associated with future development of MetS in healthy middle-aged men.

Serum uric acid and subsequent cognitive performance in patients with pre-existing cardiovascular disease

High serum uric acid (UA) levels are associated with numerous vascular risk factors, and vascular disease, that predispose patients to cognitive impairment, yet UA is also a major natural antioxidant and higher levels have been linked to slower progression of several neurodegenerative disease. In-order to test the association between UA and subsequent cognitive performance among patients that carry a high vascular burden, UA levels were determined by calorimetric enzymatic tests in a sub-cohort of patients with chronic cardiovascular disease who previously participating in a secondary prevention trial. After an average of 9.8±1.7 years, we assessed cognitive performance (Neurotrax Computerized Cognitive Battery) as well as cerebrovascular reactivity (CVR) and common carotid intima-media thickness (IMT). Among 446 men (mean age 62.3±6.4 yrs) mean UA levels were 5.8±1.1 mg/dL. Adjusted linear regression models revealed that low UA levels (bottom quintile) were associated with poorer cognitive performance. Adjusted differences between the bottom quintile and grouped top UA quintiles were (B coefficient±SE) −4.23±1.28 for global cognitive scores (p = 0.001), −4.69±1.81 for memory scores (p = 0.010), −3.32±1.43 for executive scores (p = 0.020) and −3.43±1.97 for visual spatial scores (p = 0.082). Significant difference was also found for attention scores (p = 0.015). Additional adjustment for impaired CVR and high common carotid IMT slightly attenuated the relationship. Stronger UA effect on cognitive performance was found for older (age>65) patients with significant age interaction for global cognitive score (p = 0.016) and for executive (p = 0.018) and attention domains (p<0.001). In conclusion, we demonstrate that low UA levels in patients with preexisting cardiovascular disease are associated with poorer cognitive function a decade later. These findings lend support to the hypothesis that oxidative stress may be involved in the pathogenesis of age-associated cognitive impairment.

Nonalcoholic fatty liver disease: a precursor of the metabolic syndrome

The conventional paradigm of nonalcoholic fatty liver disease representing the "hepatic manifestation of the metabolic syndrome" is outdated. We identified and summarized longitudinal studies that, supporting the association of nonalcoholic fatty liver disease with either type 2 diabetes mellitus or metabolic syndrome, suggest that nonalcoholic fatty liver disease precedes the development of both conditions. Online Medical databases were searched, relevant articles were identified, their references were further assessed and tabulated data were checked. Although several cross-sectional studies linked nonalcoholic fatty liver disease to either diabetes and other components of the metabolic syndrome, we focused on 28 longitudinal studies which provided evidence for nonalcoholic fatty liver disease as a risk factor for the future development of diabetes. Moreover, additional 19 longitudinal reported that nonalcoholic fatty liver disease precedes and is a risk factor for the future development of the metabolic syndrome. Finally, molecular and genetic studies are discussed supporting the view that aetiology of steatosis and lipid intra-hepatocytic compartmentation are a major determinant of whether fatty liver is/is not associated with insulin resistance and metabolic syndrome. Data support the novel paradigm of nonalcoholic fatty liver disease as a strong determinant for the development of the metabolic syndrome, which has potentially relevant clinical implications for diagnosing, preventing and treating metabolic syndrome.

Associations between serum uric acid concentrations and metabolic syndrome and its components in the PREDIMED study

BACKGROUND AND AIMS

Several studies have demonstrated a relationship between increased serum uric acid (SUA) concentrations and the prevalence of metabolic syndrome (MetS) in the oriental population. However, to the best of our knowledge, the association between SUA and MetS has never been investigated in elderly European individuals at high cardiovascular risk. The aim of this study was to conduct a cross-sectional and prospective evaluation of the associations between SUA concentrations and the MetS in elderly individuals at high cardiovascular risk.

METHODS AND RESULTS

Men and women (55-80 years of age) from different PREDIMED (Prevención con DIeta MEDiterránea) recruiting centers were studied. Baseline cross-sectional (n = 4417) and prospective assessments (n = 1511) were performed. MetS was defined in accordance with the updated harmonized criteria. Anthropometric measurements and biochemical determinations were assessed at baseline and yearly during follow-up. Unadjusted and adjusted regression models were fitted to assess the risk of MetS and its components according to the levels of baseline SUA. Participants in the highest baseline sex-adjusted SUA quartile showed an increased prevalence of MetS than those in the lowest quartile, even after adjusting for potential confounders (odd ratio (OR): 2.3 (95% confidence interval (CI), 1.8-2.8); P < 0.001). Participants in the highest baseline sex-adjusted SUA quartile presented a higher incidence of new-onset MetS than those in the lowest quartile (hazard ratios (HR): 1.4 (95% CI, 1.1-1.9); P < 0.001). Participants initially free at baseline of hypertriglyceridemia (HR: 1.9 (1.6-2.4); P < 0.001), low high-density lipoprotein (HDL)-cholesterol (HR: 1.4 (1.1-1.7); P = 0.002), and hypertension components of MetS (HR: 2.0 (1.2-3.3); P = 0.008) and who were in the upper quartile of SUA had a significantly higher risk of developing these MetS components during follow-up.

CONCLUSIONS

Elevated SUA concentrations are significantly associated with the development of MetS.

Prevalence of metabolic syndrome and pre-metabolic syndrome in health professionals: LATINMETS Brazil study

BACKGROUND

The metabolic syndrome (MS) is characterized by several cardiovascular risk factors and is associated with an increased incidence of diabetes, cardiovascular events and mortality. The prevalence of MS is increasing in epidemic proportions worldwide. The present study aimed to investigate the prevalence of MS and its components in health professionals in the municipality of Viçosa, Brazil.

METHODS

Cross-sectional observational study in the frame of the LATIN America METabolic Syndrome (LATINMETS) multicenter study. The study sample consisted of 226 healthcare personnel (20-59 years). Weight, height, waist circumference and hip circumference were determined. The following anthropometric indices were calculated: body mass index (BMI), waist/hip ratio, waist/height ratio, body adiposity index (BAI) and conicity index. Body composition was assessed by tetrapolar bioelectrical impedance. The lipid profile, fasting glucose, insulin, uric acid, high-sensitive C-reactive protein (hs-CRP) and complement C3 were measured in fasting conditions. Insulin resistance was assessed by the Homeostasis Model Assessment Index of Insulin Resistance (HOMA-IR).

RESULTS

Of the 226 healthcare individuals included in the study, 74.3% were female, 77.0% graduated and 23.0% students of the last two years of courses in health area, with a median age of 27 years. The overall prevalence of MS was 4.5%, and increased with age (20 to 29 years: 1.3%; 30 to 39 years: 5.6%; ≥ 40 years: 26.3%) (P < 0.01). The presence of pre-MS and MS was associated with several measures of adiposity, total cholesterol/HDL-c and LDL-c/HDL-c ratios and serum complement C3 concentrations.

CONCLUSIONS

The LATINMETS Brazil study reported an association between MS prevalence and age, especially in those over 40 years. The presence of MS is associated with an increased prevalence of several cardiovascular risk factors.

Serum uric acid does not predict incident metabolic syndrome in a population with high prevalence of obesity

AIM

To evaluate whether uric acid (UA) predicts 4-yr incidence of metabolic syndrome (MetS) in non-diabetic participants of the Strong Heart Study (SHS) cohort.

METHODS AND RESULTS

In this population-based prospective study we analyzed 1499 American Indians (890 women), without diabetes or MetS, controlled during the 4th SHS exam and re-examined 4 years later during the 5th SHS exam. Participants were divided into sex-specific tertiles of UA and the first two tertiles (group N) were compared with the third tertile (group H). Body mass index (BMI = 28.3 ± 7 vs. 31.1 ± 7 kg/m(2)), fat-free mass (FFM = 52.0 ± 14 vs. 54.9 ± 11 kg), waist-to-hip ratio, HOMA-IR (3.66 vs. 4.26), BP and indices of inflammation were significantly higher in group H than in group N (all p < 0.001). Incident MetS at the time of the 5th exam was more frequent in group H than group N (35 vs. 28%, OR 1.44 (95% CI = 1.10-1.91; p < 0.01). This association was still significant (OR = 1.13, p = 0.04) independently of family relatedness, sex, history of hypertension, HOMA-IR, central adiposity and renal function, but disappeared when fat-free mass was included in the model.

CONCLUSIONS

In the SHS, UA levels are associated to parameters of insulin resistance and to indices of inflammation. UA levels, however, do not predict incident MetS independently of the initial obesity-related increased FFM.

Association between serum 25-hydroxyvitamin D level and insulin resistance in a rural population

PURPOSE

A low serum 25-hydroxyvitamin D [25(OH)D] level in the blood has been correlated with an increased risk of diabetes mellitus; however, the association between serum 25(OH)D level and insulin resistance has not been established in a Korean rural population. The aim of this study was to investigate the independent association between serum 25(OH)D level and insulin resistance in rural Korean adults.

MATERIALS AND METHODS

This study used data from the Korean Genome Epidemiology Study-Kangwha Study. In the 2011 study, 1200 adults completed health examinations. In an ancillary study, serum 25(OH)D level was measured in a subsample (n=813). After excluding those taking vitamin D supplements, a cross-sectional analysis was carried out on 807 participants (324 men and 483 women) aged 40 to 89 years old. Measured from overnight fasting blood samples, glucose and insulin levels were used to calculate the homeostasis model assessment for insulin resistance (HOMA-IR). Measures of glucose, insulin, and HOMA-IR were log-transformed for parametric tests.

RESULTS

Serum 25(OH)D level was inversely associated with HOMA-IR (β=-0.003, p=0.039) in a univariate analysis. However, the association was not significant after adjustment for sex and age (β=-0.002, p=0.123) or after adjustment for sex, age, body mass index, smoking status, alcohol intake, and regular exercise (β=-0.003, p=0.247).

CONCLUSION

Our findings suggest that vitamin D is not independently associated with insulin resistance in Korean men and women.

Comorbidities in patients with crystal diseases and hyperuricemia

Crystal arthropathies are among the most common causes of painful inflammatory arthritis. Gout, the most common example, has been associated with cardiovascular and renal disease. In recent years, evidence for these associations and those involving other comorbidities, such as the metabolic syndrome, have emerged, and the importance of asymptomatic hyperuricemia has been established. In this review, an update on evidence, both experimental and clinical, is presented, and associations between hyperuricemia, gout, and several comorbidities are described. Causality regarding calcium pyrophosphate arthropathy and associated comorbidities is also reviewed.

Risk factors for incident hyperuricemia during mid-adulthood in African American and white men and women enrolled in the ARIC cohort study

Background

Increased serum urate levels are associated with poor outcomes including but not limited to gout. It is unclear whether serum urate levels are the sole predictor of incident hyperuricemia or whether demographic and clinical risk factors also predict the development of hyperuricemia. The goal of this study was to identify risk factors for incident hyperuricemia over 9 years in a population-based study, ARIC.

Methods

ARIC recruited individuals from 4 US communities; 8,342 participants who had urate levels <7.0 mg/dL were included in this analysis. Risk factors (including baseline, 3-year, and change in urate level over 3 years) for 9-year incident hyperuricemia (urate level of >7.0 g/dL) were identified using an AIC-based selection approach in a modified Poisson regression model.

Results

The 9-year cumulative incidence of hyperuricemia was 4%; men = 5%; women = 3%; African Americans = 6% and whites = 3%. The adjusted model included 9 predictors for incident hyperuricemia over 9 years: male sex (RR = 1.73 95% CI: 1.36-2.21), African-American race (RR = 1.79 95% CI: 1.37-2.33), smoking (RR = 1.27, 95% CI: 0.97-1.67), <HS education (RR = 1.27, 95% CI: 0.99-1.63), hypertension (RR = 1.65, 95% CI: 1.30-2.09), CHD (RR = 1.57, 95% CI: 0.99-2.50), obesity (class I RR = 2.37, 95% CI: 1.65-3.41 and ≥ class II RR = 3.47, 95% CI: 2.33-5.18), eGFR < 60 (RR = 2.85, 95% CI: 1.62-5.01) and triglycerides (Quartile 4 vs. Quartile 1: RR = 2.00, 95% CI: 1.38-2.89). In separate models, urate levels at baseline (RR 1 mg/dL increase = 2.33, 95% CI: 1.94-2.80) and 3 years after baseline (RR for a 1 mg/dL increase = 1.92, 95% CI: 1.78-2.07) were associated with incident hyperuricemia after accounting for demographic and clinical risk factors.

Conclusion

Demographic and clinical risk factors that are routinely collected as part of regular medical care are jointly associated with the development of hyperuricemia.

Metabolic syndrome, diabetes, and hyperuricemia

PURPOSE OF REVIEW

To explore the causal relationship between metabolic syndrome, type 2 diabetes and hyperuricemia.

RECENT FINDINGS

The prevalence of hyperuricemia in male adults with metabolic syndrome was increased and a large difference in prevalence of metabolic syndrome also existed in those with hyperuricemia compared with normouricemia. Even in those with normouricemia, higher serum uric acid levels were associated with metabolic syndrome. Serum uric acid was an independent risk factor for incident diabetes, and evidence showed that the patients with both gout and type 2 diabetes exhibited a mutual inter-dependent effect on higher incidences. Furthermore, obese patients often demonstrated insulin resistance and adipose tissue macrophage with low-grade inflammation, which is suggested to be the major contributor. Although alcohol intake is considered a risk for developing hyperuricemia, moderate alcohol intake showed a lower risk for developing type 2 diabetes and insulin resistance. Hyperinsulinemia reduces renal excretion of uric acid on the proximal tubular of the kidney leading to hyperuricemia, which has deleterious effects on endothelial function and on nitric oxide bioavailability, thus causing hyperinsulinemia.

SUMMARY

We found evidence to suggest that insulin resistance plays a potentially key role in the causal relationship between metabolic syndrome, type 2 diabetes and hyperuricemia. Furthermore, it is likely that hyperuricemia and insulin resistance share a bidirectional causal effect.

The liver and the kidney: two critical organs influencing the atherothrombotic risk in metabolic syndrome

The increased atherothrombotic risk in patients with metabolic syndrome (MetS) has been classically explained by the multiplicative effect of systemic concomitant pro-atherosclerotic factors. In particular, centripetal obesity, dyslipidaemia, glucose intolerance, hypertension (differently combined in the diagnosis of the disease) would be expected to act as classical cardiovascular risk conditions underlying accelerated atherogenesis. In order to better understand specific atherosclerotic pathophysiology in MetS, emerging evidence focused on the alterations in different organs that could serve as both pathophysiological targets and active players in the disease. Abnormalities in adipose tissue, heart and arteries have been widely investigated in a variety of basic research and clinical studies in MetS. In this narrative review, we focus on pathophysiological activities of the liver and kidney. Considering its key role in metabolism and production of soluble inflammatory mediators (such as C-reactive protein [CRP]), the liver in MetS has been shown to be altered both in its structure and function. In particular, a relevant amount of the fat accumulated within this organ has been shown to be associated with different degrees of inflammation and potential insulin resistance. In humans, non-alcoholic fatty liver disease (NAFLD) has been described as the hepatic manifestation of MetS. In an analogous manner, epidemiological evidence strongly suggested a "guilty" association between MetS and chronic kidney disease (CKD). Some biomarkers of hepatic (such as C-reactive protein, TNF-alpha or other cytokines) and renal diseases (such as uric acid) associated with MetS might be particularly useful to better manage and prevent the atherothrombotic risk.

Relationship between serum uric acid levels and metabolic syndrome in Chinese postmenopausal women

OBJECTIVE

Serum uric acid levels have been reported to be associated with metabolic syndrome (MetS). However, few studies specifically examining the relationship between serum uric acid (SUA) levels and MetS in postmenopausal women have been reported in China. Thus, we conducted this study in order to assess the relationship between SUA levels and MetS in Chinese postmenopausal women.

METHODS

A cross-sectional study of 1022 Chinese postmenopausal women (aged 42-80 years) who participated in annual health check-ups was employed. MetS was defined by National Cholesterol Education Program/Adult Treatment Panel III criteria (NCEP-ATP III). Of all the participants, 385 women were diagnosed with MetS (MetS group) and the others were without MetS (non-MetS group). SUA quartiles were defined as follows: Q1, < 3.9 mg/dl; Q2, 3.9-4.5 mg/dl; Q3, 4.6-5.1 mg/dl; Q4, 5.2-6.0 mg/dl. The association between SUA quartiles and MetS was assessed using binary logistic regression.

RESULTS

The adjusted odds ratio (95% confidence interval) for the presence of metabolic syndrome in the highest SUA quartile vs. the lowest quartile was 3.768 (2.386-5.950) for all women (p < 0.01) after adjusting for age, body mass index, blood urea nitrogen, serum creatinine, total cholesterol, low density lipoprotein cholesterol and C-reactive protein. The presence of MetS significantly increased in the second, third and fourth quartiles of SUA. The prevalence of MetS increased gradually with an increasing serum uric acid quartile (p for trend < 0.001).

CONCLUSION

Higher SUA levels are positively and independently associated with the presence of MetS in Chinese postmenopausal women.