Incidence and predictors of iodinated contrast media-induced hypothyroidism and hyperthyroidism in patients undergoing coronary angiographic procedures: A longitudinal study from East India

ABSTRACT Introduction: The prevalence of iodinated contrast media (ICM)-induced thyroid dysfunction varies by regional iodine sufficiency, and there is currently no global standard for screening before or after ICM-based procedures. Transient thyroid disturbances can have serious clinical consequences following coronary angiographic (CAG) procedures. India is now predominantly iodine sufficient, but there is no regional data to guide policies to prevent ICM-induced thyroid dysfunction in the country. Methods: A longitudinal study was conducted in patients without preexisting overt thyroid disease, undergoing CAG. Thyroid function tests were performed before the procedure, and then at 6 weeks and 3 months post-CAG. Multiple-logistic-regression analyses were used to identify predictors of ICM-induced hypothyroidism (ICM-hypo) and hyperthyroidism (ICM-hyper). Results: Among 105 patients, 22 (20.9%) developed ICM-induced thyroid dysfunction after CAG: 15 (14.3%) had hypothyroidism, and 7 (6.7%) had hyperthyroidism at 6 weeks. At 3 months, 5 (4.8%) had overt hypothyroidism, and 1 had overt hyperthyroidism. Independent predictors for ICM-Hypo included ICM-procedure within the last year (odds ratio [OR]: 14.87, 95% confidence interval [CI] 1.86–131, P = 0.01) and anti-thyroid-peroxidase antibody (TPO-Ab) positivity (OR: 16.71, 95% CI 4.06–87.8). Predictors for ICM-Hyper were anti-TPO-antibody positivity (OR: 8.71, 95% CI 1.01–108.8), contrast-induced acute kidney injury (AKI) (OR: 37.29, 95% CI 3.39–1035, P = 0.008), and lower baseline thyroid-stimulating hormone (TSH) (OR: 0.1, 95% CI 0.01–0.51). Conclusion: ICM caused thyroid dysfunction in one-fifth of patients undergoing CAG, though mostly transient. Even transient thyroid disorders may cause new-onset arrhythmia or heart failure in them. Routine thyroid testing before, and periodically post-CAG, is advisable, particularly for those with recent ICM exposure, contrast-induced AKI, or anti-TPO-positivity.