Thyroid dysfunctions are a cause of morbidity and disability worldwide. Little information has been found on the prevalence of thyroid dysfunctions in Paraguay, so this study provides data on their presentation. The objective was to determine the prevalence of thyroid dysfunction and its relationship with the lipid profile in adult outpatients attending the laboratory of the Regional Hospital of Encarnación, during January-November 2016. A descriptive cross-sectional study was performed, based on the review of 250 medical records, 84 % of whom were women; the median age was 39 (35-47) years in men and 36 (32-43) years in women. Thirty percent were hypothyroid and 3 % hyperthyroid; the most frequent thyroid dysfunction was subclinical hypothyroidism with 19 %. Highly significant differences were found for total cholesterol, LDL, VLDL and thyrotrophin between hypothyroid vs euthyroid, with the former having more atherogenic profiles. Logistic regression was used to assess the contribution of dyslipidaemia, finding a significant association with hypothyroidism (OR=3.24(1.81-5.81), p<0.001). Thirty-three percent of this population sample, 1 in 3 individuals, had thyroid dysfunction. These could be managed appropriately and further complications could be avoided.