Thyroid Nodules in Severely Obese Patients: Frequency and Risk of Malignancy on Ultrasonography

ABSTRACT

Background: We aimed to compare the thyroid ultrasonographic findings of severely obese versus nonobese individuals, and the frequency, characteristics, and risk of malignancy in detected nodules.

Design: Case-control study including 67 adults with severe obesity (body mass index [BMI] ≥ 35 kg/m²) and 67 nonobese controls (BMI < 30 kg/m²). The participants underwent ultrasound evaluation of the thyroid and cervical subcutaneous tissue. The risk of malignancy in detected nodules was determined using the American Thyroid Association (ATA) 2015 and the Thyroid Imaging Reporting and Data System (TI-RADS) classifications. Fine-needle aspiration biopsy (FNAB) was performed in nodules for which the procedure was recommended according to the ATA-2015 or TI-RADS criteria, and the cytological evaluation followed the Bethesda classification.

Results: The mean BMI values in the case and control groups were 47.0 ± 6.1 kg/m² and 22.8 ± 2.7 kg/m², respectively. There were no differences between groups regarding sex, age, total T3, and antiperoxidase (antiTPO) antibody positivity. When compared with controls, severely obese individuals showed a greater frequency of parenchymal hypoechogenicity (p = 0.042), cervical subcutaneous tissue thickness (p < 0.001), overall frequency of thyroid nodules (p = 0.038), and frequency of multiple nodules (p = 0.013). No significant differences were observed in terms of risk of nodular malignancy according to both the ATA-2015 and TI-RADS classifications in severely obese compared with nonobese individuals.

Conclusions: Severely obese individuals (versus nonobese controls) presented increased parenchymal hypoechogenicity and frequency of thyroid nodules on ultrasonographic evaluation. However, no significant differences were observed in terms of risk of nodular malignancy between both groups according to the ATA-2015 and TI-RADS criteria. Thus, ultrasonographic thyroid screening of severely obese individuals is not justified.

KEYWORDS:

• Thyroid nodule
• thyroid cancer
• obesity
• ultrasonography
• case-control studies

Acknowledgments

Our heartfelt thanks to the Goiás State Research Support Foundation (FAPEG) for providing the financial resources for the primary study from which the cases were recruited; to the Municipal Health Secretary for referring patients to the Nutrition in Severe Obesity Outpatient Clinic (ANOG); to the Severe Obesity Study Group (GEOG) at the Clinical Research Unit of HC/UFG, for collecting the data of the participants in the case group; to Thalyta at Laboratório Rômulo Rocha, where the biochemical analyses were performed; to Carlos Ximenes Filho and Élbio de Paula at the CAPC laboratory, where the FNAB and cytological analysis were performed; to the multidisciplinary team involved in the study, for their hard work and enthusiasm; and mainly to the patients for participating in the study and contributing to science advance. We also would like to thank Milena Braga-Basaria, M.D. (Voxmed Medical Communications) for critically reviewing and suggesting improvements to the manuscript.

Disclosure Statements

The authors declare no conflict of interest.

Additional information

Funding

This study was partially funded by the Goiás State Research Support Foundation (FAPEG) (grant number 201310267000003). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.