A ‘goitre’ refers to any type of enlargement of the thyroidgland. The enlargement can be diffuse, nodular (one solidnodule) or multinodular (more than one nodule), and itmay be present in those with hypothyroidism, hyperthyroidism or normal thyroid functions [1]. A nodular goitre (NG)is a clinically recognizable enlargement of the thyroid glandthat is characterized by excessive growth and structural orfunctional transformation of one or several areas within normal thyroid tissue [2]. In our study, a solitary thyroid nodule is referred to as a NG, and more than one thyroidnodule is referred to as a multinodular goitre (MNG).In the absence of thyroid dysfunction, autoimmune thyroid disease, thyroiditis or thyroid malignancy, the enlargement of the thyroid gland is known as a ‘euthyroid goitre’or ‘nontoxic goitre’ [3]. Worldwide, the total goitre prevalence in the general population is estimated to be 15.8%,varying between 4.7% in the US and 28.3% in Africa [4].Turkey is an endemic goitre region, and goitres causedby iodine deficiency are an important public health problem.Duzce is a moderately iodine-deficient region in Turkey [5].Nodular thyroid diseases are very common in Turkey, witha reported prevalence of thyroid nodules of 2–6% by palpation and 18% by ultrasound imaging in studies conducted invarious regions [6,7].Metabolic syndrome (MetS) is associated with multiplecardiovascular risk factors [8]. It is estimated that one infour people around the world suffers from MetS [9]. Insulinresistance (IR) is considered as the most important component of MetS, and it is thought to directly affect thyroid diseases [10,11], together with other components of MetS, suchas obesity, raised blood pressure and lipid and glucosemetabolism abnormalities [12]. A previous study reportedthat the thyroid volume and nodule prevalence were increasedin patients with IR in an iodine-sufficient area [11].This was a population-based prospective study conductedin a moderately iodine-deficient area in Duzce, Turkey. Weinvestigated the relation between thyroid nodularity andMetS to shed light on its potential role in the increasedprevalence of thyroid nodules. We know that there is fewstudies on this subject, especially in euthyroid individuals.