Table 6 Studies evaluating the relationship between thyroid hormone levels and components of the metabolic syndrome
From: Thyroid function and metabolic syndrome in the population-based LifeLines cohort study
Author, year | N | Subjects’ age | Gender separation? | Corrections for confounders | Major findings | Ref |
|---|---|---|---|---|---|---|
Roos, 2007 | 1581, 716 M | 28–75 yrs | No | Age, sex, HOMA-IR | FT4 negative association with TC, LDL-C, TG and waist, positive association with HDL-C, FT3 negative association with TC, LDL-C, TG | [3] |
Park, 2009 | 949 | Postmeno-pausal women | Women only | Age, BMI, HOMA-IR, FT4, exercise (3 levels), alcohol (3 levels) | TSH associated with TC, LDL-C, DBP and TG, MetS | [30] |
Kim, 2009 | 44,196, 25,147 M | 25–70 yrs | Yes | Age | Men: FT4 associated with BP, HDL-C, FBG, TG, and with WC in those over 50; Women: associated with BP, HDL-C, FBG, WC; no association with MetS, when adjusted for age | [4] |
Garduno-Garcia, 2010 | 3033 | 18–70 yrs | No | Age, sex | TSH associated with TC, TG, WC; FT4 associated with HDL-C, WC, HOMA-IR; 10% had SCH. | [31] |
Ruhla, 2010 | 1333, 481Â M | >18Â yrs | No | Age | TSH positively associated with BMI, TG, MetS; no data on FT4 or FT3 | [32] |
Park, 2011 | 5998, 3469Â M | >18Â yrs | No | Age, sex, BMI, smoking (y/n), alcohol (y/n), exercise (y/n) | TSH and FT4 associated with WC, FBG, HDL-C, FT4 also with DBP; higher TSH predicted MetS at follow-up | [5] |
Tarcin, 2012 | 211, 24 M | Obesity, 18–73 yrs | No | Age | FT3/FT4 negatively associated with FBG, TG, BP, TT3 positively with HOMA-IR, FBG, WC | [33] |
Waring, 2012 | 2119 | 70–79 yrs | No | Age, sex, race, BMI, smoking, HOMA-IR | TSH associated with MetS prevalence, in entire cohort with broad range of TSH levels, and in euthyroid range | [34] |
Oh, 2013 | 2760 | 18–39 | Women only | Age, BMI, HOMA-IR | TSH between 2.5 and 4.5 associated with BMI, WC, BP, TG | [35] |
Roef, 2014 | 2315, 1177Â M | Middle-aged | No | Age, sex, height, current smoking | FT3 and FT3/FT4 ratio positively associated with BMI, WC, TG, BP, FBG, negatively with HDL-C; FT4 negatively associated with BMI, WC, TG | [36] |
Mehran, 2014 | 3755, 1709 M | ≥20 yrs | No | Age, sex, smoking, BMI, HOMA-IR | FT4 associated with HDL-C, LDL-C, TG, WC, BP, but not fasting glucose; no FT3 data | [37] |
Minami, 2015 | 283, 161 M | Children, 6–15 yrs | Yes | None | Higher FT3/FT4 ratio in boys with MetS; no difference thyroid function in girls with MetS | [38] |
Laclaustra, 2015 | 3533 M | 20–65 yrs | Men only | Age, alcohol consumption, smoking (never, former, current) | Higher TSH & lowest FT4 quintiles associated with higher MetS prevalence | [39] |
Kim, 2016 | 13,496, 8168 M | Middle-aged, 35–65 yrs | No | Age, sex, % body fat, smoking, HOMA-IR | Higher quartiles of T3 and T3/T4 ratio associated with MetS; only measured total T4 and T3 levels; modified MetS criteria | [6] |
Kim, 2017 | 12,037, 6950 M | Middle-aged, 35–65 yrs | No | Age, sex, smoking | Highest T3 quartile associated with highest 6-year MetS incidence; only measured total T4 and T3 levels; modified MetS criteria | [21] |
Ferrannini, 2017 | 940 | 30–60 yrs | No | Age, sex, BMI, WHR, family history of diabetes | Higher FT3 associated with decreased insulin sensitivity (insulin clamp), predicted follow-up increases in glycaemia | [22] |
Park, 2017 | 132,346, 66,991Â M | >18Â yrs | Yes | Age, BMI, smoking status, menopausal status (in women) | FT3FT4 ratio associated with increased risk of MetS parameters and insulin resistance | [7] |