The Association Between Subclinical Hypothyroidism and Metabolic Syndrome as Defined by the ATP III Criteria.

The association between subclinical hypothyroidism (SCH) and metabolic syndrome (MetS) is a matter of debate. In this study, we aimed to examine the risk of MetS in SCH through a systematic review and meta-analysis. A systematic search of published literature up to September 2015 was conducted. General population studies were included if they had considered SCH as the independent variable. After data extraction, a meta-analysis was run to assess the odds ratio (OR) of MetS and its components between subclinical hypothyroid and euthyroid groups. Only studies employing Adult Treatment Panel III (ATP III) criteria for MetS were included in the meta-analysis. In the SCH group, female gender was more prevalent [OR = 1.65, 95% confidence interval (95% CI) 1.29-2.13]. Meta-analysis showed no significant difference in MetS prevalence between SCH and euthyroid individuals (OR = 1.13, 95% CI 0.95-1.34). However, the prevalence of central obesity (OR = 1.43, 95% CI 1.04-1.96) was significantly higher in the SCH group. On the other hand, hypertriglyceridemia was more prevalent in the female-only SCH subgroup. In conclusion, although we found some MetS components to be more prevalent in SCH, the prevalence of MetS as defined by ATP III criteria was not increased in SCH. Considerable heterogeneity observed may have influenced the results on MetS components.