İyot Eksikliği Bölgesinde Radyografik İşlemler Sırasında İyotlu Kontrast Uygulanması Sonrası Gelişen Hipertiroidizm Sıklığı ve Etkileyen Faktörler

Abstract

The aim of this study is to evaluate the incidence and determinants of thyroid dysfunction following iodinated contrast media (ICM) exposure in a population residing in an iodine-deficient region, consisting of middle-to-older-aged individuals with high cardiovascular risk. Specifically, it aims to identify risk factors for the development of hyperthyroidism and to develop a clinically applicable risk score.Thyroid function was assessed in a total population of 385 patients, including a retrospective cohort (n=265) and a prospective cohort (n=120), who were scheduled for contrast-enhanced imaging or interventional procedures during cardiology evaluations. Baseline thyroid function tests, thyroid ultrasonography, and clinical parameters were analyzed for all patients. Risk factors associated with the development of hyperthyroidism were identified using multivariable analysis, and a nomogram-based risk score was developed. The overall incidence of hyperthyroidism following ICM exposure was found to be 12.7% (overt: 8.3%; subclinical: 4.4%). Patients who developed hyperthyroidism were older (65.8±8.7 years versus 60.5±8.7 years, p<0.001), had lower body weight (74.0±12.8 kg versus 79.8±14.5 kg, p=0.008), and larger thyroid volume (21.70 [15.90–27.55] mL versus 14.70 [11.90–19.20] mL, p<0.001). They also exhibited lower baseline TSH levels (0.77 mIU/L versus 1.72 mIU/L, p<0.001) and higher sT4 levels (13.87±3.96 pmol/L versus 11.87±2.68 pmol/L, p=0.005). The presence of nodular goiter and a family history of thyroid disease emerged as significant risk factors. Variables found significant in univariate analyses were included in a multivariate logistic regression model. Independent predictors of hyperthyroidism development were: low pre-contrast TSH (p=0.001, OR=15.254), elevated sT4 (p=0.031, OR=6.638), increased thyroid volume (p=0.009, OR=5.954), lower BMI (p=0.044, OR=3.863), and older age (p=0.028, OR=4.038). A risk score was developed based on these variables. This scoring model enables individualized risk prediction prior to contrast administration by integrating these parameters. Although 76.7% of hyperthyroid cases resolved within six months, persistent hyperthyroidism was observed in 23.3% of patients, and recurrence occurred in 18.2%. In conclusion, thyroid dysfunction is frequently observed following ICM exposure in iodine-deficient populations. This study highlights the importance of identifying high-risk individuals in advance and taking appropriate preventive measures. The risk score developed in this study may serve as a practical predictive tool in clinical settings.