Would high body mass index and TSH level affect selecting thyroid nodule for fine-needle aspiration biopsy?

Abstract

PurposeThe purpose of this study was to evaluate whether high body mass index (BMI) or thyroid stimulating hormone (TSH) level would affect selecting thyroid nodule for fine-needle aspiration biopsy (FNA).Materials and MethodsAmong thyroid nodules that were biopsied in our institution from February 2006 to December 2008, 3,155 thyroid nodules with 5 mm or larger, in patients without medication history, and with BMI and TSH values and cytopathologic results were selected. Four grades of BMI were applied (underweight, <18.5; normal, 18.5 - 24.9; overweight, 25 - 29.9; obese, ≥30) and TSH levels were classified into low, normal, and high. Ultrasound (US) features of the thyroid nodules were divided into ‘probably benign’ and ‘suspicious for malignancy’ categories. Univariate and multivariate logistic regression analysis were used to find the association between variables and malignancy. We tested interactions on a multiplicative scale to evaluate whether the associations between BMI grade and malignancy is different by age group or gender. ResultsThe grades of BMI showed difference between malignant and non-malignant groups (P = .016). The TSH levels were significantly different between the malignant and non-malignant groups (P < .001) showing higher percentage of high TSH level among malignant group (22.0%) compared to non-malignant group (11.4%). Multivariate analysis showed no significant association between high BMI and malignancy. Thyroid malignancy showed significant association with ‘suspicious for malignancy’ US category (OR = 1.883, P < .001) and high TSH level (OR = 1.095, P < .001). High TSH level showed significant association with malignancy in nodules with ‘suspicious for malignancy’ US category (OR = 1.178, P < .001), but not in nodules with ‘probably benign’ US category (OR = 1.022, P = .281). On multivariate analysis

according to age groups, being obese from the ages of 60 to 69 years were significantly associated with a malignancy (OR = 1.173, P = .033).ConclusionHigh BMI and TSH level did not give additional information for selecting thyroid nodule for FNA with US. However, being obese in late adulthood was significantly associated with malignancy.