Elsevier

Metabolism

Volume 56, Issue 6, June 2007, Pages 751-756
Metabolism

Serum uric acid and leptin levels in metabolic syndrome: a quandary over the role of uric acid

https://doi.org/10.1016/j.metabol.2007.01.006Get rights and content

Abstract

This study investigates the impact of uric acid (UA) on the risk factors associated with metabolic syndrome. In addition, this study explores the relationship between UA and insulin resistance and serum leptin levels in metabolic syndrome. A total of 470 subjects (252 women and 218 men) were recruited from the Department of Health Management at Chang Gung Medical Center (Linkou, Taiwan). Metabolic syndrome was defined using a modified Adult Treatment Panel III (ATP III) definition. The formula for the homeostasis model assessment of insulin resistance (HOMA-IR) is as follows: fasting serum insulin (μU/mL) × fasting plasma glucose (mmol/L)/22.5. Diabetes mellitus was diagnosed in 45 subjects (9.6%); 82 subjects (17.4%) had hypertension. Hyperuricemia was diagnosed in 144 subjects (30.6%). Of these subjects, 115 (63 females and 52 males) (24.5%) were diagnosed as having metabolic syndrome. Patients with hyperuricemia had increased body mass index, waist-to-hip ratio, and triglyceride (Tg) level. The subjects also had lower high-density lipoprotein and greater hypertension. Hormone assays showed an elevation of leptin, immunoreactive insulin (IRI), and HOMA-IR in the hyperuricemia group. Uric acid appeared to be better correlated with Tg, blood pressure (both systolic and diastolic), obesity, immunoreactive insulin, and HOMA-IR. Uric acid did not correlate with leptin or blood glucose levels. Metabolic syndrome and Tg/high-density lipoprotein ratio showed a statistically significant difference in HOMA-IR using 3.8 as a cutoff value. Otherwise, there was no difference in leptin value. In conclusion, serum UA is significantly related to risk factors of metabolic syndrome except for blood glucose. Waist-to-hip ratio and HOMA-IR were statistically different in subjects with and without metabolic syndrome.

Introduction

Serum uric acid (UA) is an important factor in cardiovascular events, but its role in metabolic syndrome is controversial [1], [2]. Factors such as age group, ethnic population, and sex illustrate the importance of serum UA levels in metabolic syndrome [3], [4]. Genetic characteristics, body mass structure, aging, and renal disposal ability influence serum UA levels. A recent familial clustering study of metabolic syndrome showed a significant genetic correlation between UA and body mass index (BMI), waist circumference, high-density lipoprotein (HDL) cholesterol, triglyceride (Tg), and plasminogen activator inhibitor 1 antigen [5]. The present study was conducted to investigate the impact of UA on various risk factors associated with metabolic syndrome. In addition, we examined the relationship between serum leptin levels and UA in metabolic syndrome in Chinese subjects affected by insulin resistance.

Section snippets

Subjects

A total of 470 subjects, including 252 women (mean age ± SD, 53.7 ± 12.2 years) and 218 men (mean age ± SD, 54.6 ± 13.5 years), were randomly selected from the health examination unit of the Chang Gung Medical Center in Linkou, Taiwan. All of the subjects were Chinese residents of Taiwan. Blood tests, body scanning, and evaluation of anthropometric measurements were performed on all subjects.

Metabolic syndrome definition

Blood pressure levels were classified according to the 1999 World Health Organization-International

Metabolic parameter values in study subjects

Of the 470 subjects, 115 (63 females and 52 males) (24.5%) were diagnosed as having metabolic syndrome. Forty-five (9.6%) subjects were diagnosed as having DM; 82 (17.4%) had hypertension. Hyperuricemia was identified in 144 subjects (30.6%), 30.7% (67/218) of the male subjects and 30.6% (77/252) of the female subjects. The incidence of hypertension, DM, central obesity, as well as the values of leptin level, HOMA-IR, IRI, UA, and BMI are shown in Fig. 1. The incidence of hypertension and DM

Discussion

Insulin resistance estimated using HOMA-IR is the main factor to consider in the development of metabolic syndrome and cardiovascular complications [13]. This study confirmed the importance of HOMA-IR as a risk factor of metabolic syndrome. Furthermore, in the present study, subjects with hyperuricemia had a higher HOMA-IR. Analysis of subcutaneous fat obesity and visceral fat obesity by computed tomographic scan showed that visceral fat obesity is linked more closely to the overproduction of

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