Metabolic syndrome in normal-weight Iranian adults
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Background: The risk of metabolic risk factors increases in Middle-Eastern adults within the normal limits of BMI. There is a report that 30.1% of the Iranian population had metabolic syndrome but no reports on the prevalence of this syndrome among individuals within the various BMI categories are available. The present study estimates the prevalence of metabolic syndrome in adult population with normal levels of BMI (18.5-24.9 kg/m2). Methods: In this population-based cross-sectional study, a representative sample of 3444 subjects (1737 males and 1707 females) aged?20 years with normal body mass index (BMI= 18.5-24.9 kg/m2 for both genders) were included. Demographic data were collected; anthropometric indices and blood pressure were measured according to standard protocol. Biochemical analysis was conducted on fasting blood samples. The metabolic syndrome was defined according to the ATP III guidelines as the presence of three or more of the metabolic factors. Means and proportions, and multivariate odds ratios that quantify the association between metabolic syndrome and normal BMI quartiles, controlling for age, physical activity, smoking and education were presented. Results: The overall prevalence of the metabolic syndrome in normal weight men and women were 9.9% (CI 95%: 8.49-11.30) and 11.0% (CI 95%: 9.5-12.4, P=0.2), respectively. Men had slightly lower BMI than women (22.4آ±1.8 vs. 22.5آ±1.7 kg/m 2, P<0.001), while their WC was higher (79.8آ±6.6 vs.79.3آ±7.7 cm, P<0.001). The prevalence of high WC and low HDL was higher in women, while high blood pressure, high triglyceride levels and having at least two metabolic risk factors were more prevalent in men. Individuals at the highest category of normal BMI had significantly higher odds for being at risk for metabolic syndrome compared to those at first category (OR; 5.21 for men and 2.15 for women). There was a significant increasing trend in odds for having all the metabolic syndrome components except for high FBS and high WC in men. Women revealed a similar increasing trend except for high FBS across normal BMI quartiles. Conclusion: Normal weights Iranians have excess cardiovascular risk. Therefore interventions for prevention of diabetes and cardiovascular disease could be considered in normal weight population. On the other hand, the cut-points of BMI, suggested by WHO, may be inappropriate for the Iranian adult population.