Thyroid function in adult Nigerians with metabolic syndrome.

Introduction: Metabolic syndrome and thyroid dysfunction are two common disorders encountered in the metabolic clinic. Recently, there has been increased interest in the association between the two disorders because of the similarities between symptoms of hypothyroidism and components of the metabolic syndrome. While some reports suggest that metabolic syndrome is associated with subclinical hypothyroidism, this concept is largely under investigated in Nigerian adults with metabolic syndrome. The aim of this study is to determine the thyroid function status of adult Nigerians with metabolic syndrome and determine the association, if any, between metabolic syndrome and thyroid function.

Methods: This was a cross sectional study of one hundred and fifty adults, members of staff of the College of Medicine of the University of Lagos. The participants were recruited using a cluster random sampling method. The Ethical Research & Review Committee of the institution approved the study protocol and signed informed consent was obtained from the participants. The statistics was analysed using the IBM SPSS Software of version 19.0. The Student's t test, Chi square test and multivariate regression analysis were employed for the analysis. Statistical significance was set at p < 0.05.

Results: Thirty nine (twenty-six percent) of the study participants had metabolic syndrome and one hundred and eleven (seventy-four percent) of the study participants did not have metabolic syndrome, served as controls. Those who had metabolic syndrome group were significantly older (p = 0.03), metabolic syndrome was significantly associated with the female gender (p = 0.0002), higher systolic blood pressure (p = 0.0034), diastolic blood pressure (p = 0.0009), waist circumference (p < 0.0001), body mass index (p < 0.0001), waist-hip ratio (p = 0.003), fasting serum glucose (p = 0.0457) and free thyroxine (fT4) levels (p = 0.0496). Those with metabolic syndrome had significantly lower HDL (P = 0.004) and free triiodothyronine (fT3) levels (p = 0.037). There was no statistically significant difference in the thyroid stimulating hormone (TSH) levels between individuals with and without metabolic syndrome. Thirty-three percent of the metabolic syndrome cases had sick euthyroid syndrome (p= < 0.0001). In multivariate regression, waist circumference was significantly and inversely associated with the sick euthyroid syndrome (p = 0.011).

Conclusion: Metabolic syndrome is associated with the sick euthyroid syndrome in adult Nigerians. Abdominal obesity appears to be the link between metabolic syndrome and the sick euthyroid syndrome.