Are Plasma Thyroid-Stimulating Hormone Levels Associated with Degree of Obesity and Metabolic Syndrome in Euthyroid Obese Patients? A Turkish Cohort Study
We aimed to observe the association between degree of obesity and metabolic syndrome and plasma thyrotropin levels in obese, euthyroid Turkish patients. 947 obese and overweight patients who admitted to our outpatient clinic were assessed retrospectively. 150 healthy euthyroid cases were also recruited as the control group. Cases with metabolic syndrome were determined. Patients were divided into various subgroups as overweight, obese, morbid obese, men, and women. No statistical significance was determined when all the patients’ and subgroups’ plasma thyrotropin levels were compared to normal weight control group. No association was shown between the presence of metabolic syndrome and plasma thyrotropin levels for both all patients and subgroups. Also there was not any association between each component of metabolic syndrome and plasma thyrotropin levels. In conclusion, we did not found any significant association between plasma thyrotropin levels and obesity and metabolic syndrome in our euthyroid subjects. 1. Introduction Obesity is a serious health problem closely associated with insulin resistance and metabolic syndrome [1]. It has a complex pathophysiology characterized by interaction of genetic, environmental, and physiological factors [2]. Thyroid dysfunction is very well known to contribute to the pathogenesis of obesity. Weight loss is a common manifestation of hyperthyroidism and its treatment results in weight gain about four kilograms per year [3]. In contrast, weight gain is frequently seen in hypothyroidism and treatment causes mild weight loss [4]. The clinical observations mentioned above raise the questions of whether thyroid-stimulating hormone (TSH) change in physiological limits is associated with obesity and whether there is a link between adipose tissue and hypothalamo-thyroidal axis [5, 6]. Some studies have shown positive correlation between obesity and plasma TSH levels in euthyroid subjects; nevertheless, conflicting studies are also present [7–10]. Metabolic syndrome is an important predictor of cardiovascular risk and is a cluster of abnormalities such as abdominal obesity, dyslipidemia, high plasma glucose, and hypertension [11]. Besides their impact on energy homeostasis, thyroid hormones are known to have a variety of effects on metabolic syndrome determinants [12–14]. There are some studies which show an association between thyroid hormone levels and metabolic syndrome in euthyroid patients, but the presence of counter studies creates discrepancy [15, 16]. Conflicting results of different studies may be attributed to
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