Iodinated Contrast Medium Exposure During Computed Tomography Increase the Risk of Subsequent Development of Thyroid Disorders in Patients Without Known Thyroid Disease

Abstract

To investigate the association between iodinated contrast medium (ICM) exposure during computed tomography (CT) and the subsequent development of thyroid disorders in patients without known thyroid disease in Taiwan, an iodine-sufficient area.We conducted a population-based cohort study by using data from 1996 to 2012 in the Taiwan National Health Insurance Research Database. A total of 33,426 patients who underwent ICM-enhanced CT were included as the study cohort. To avoid selection bias, we used propensity score and matched for the index year (defined as the year of first ICM exposure) to retrieve 33,426 patients as the comparison cohort. No patients in the 2 cohorts had any known thyroid disease before the index year. Patients with a history of amiodarone treatment or coronary angiography and those with <1 year follow-up were excluded. Participants were followed until a new diagnosis of thyroid disorder or December 31, 2011. Hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated using the Cox proportional hazards regression.An association was identified between ICM exposure and the subsequent development of thyroid disorders after adjustment for potential confounders (adjusted HR = 1.17; 95% CI: 1.07–1.29; P = 0.001). Male patients and patients’ ages ≥40 years in the ICM-exposure cohort had a higher adjusted HR for developing thyroid disorders than did those in the non-ICM-exposure cohort. Hypothyroidism had the highest adjusted HR (HR = 1.37; 95% CI: 1.06–1.78; P < 0.05) among all thyroid disorders and had a higher risk of development or detection during >0.5-year post-ICM exposure compared with that during ≤0.5-year post-ICM exposure (HR = 1.26; 95% CI: 1.01–1.58; P < 0.05). Repeated ICM exposure increased the risk of thyroid disorders in patients who accepted >1 time of ICM per year on average compared with those who accepted ≤1 time per year on average (adjusted HR = 3.04; 95% CI: 2.47–3.73; P < 0.001).This study identified ICM exposure during CT as a risk factor for the subsequent development of thyroid disorders in patients without known thyroid disease, particularly in patients with repeated exposure.

The Impact of Iodinated Contrast Media Used in Epidural Steroid Injections on Thyroid Function Tests

“…An average 1,5 − 2 ml dosage of ICM with a 35µg/ml concentration is used in the procedure, providing 70µg of free iodide, which is much lower than CT or angiography ranges [11,12]. Some research indicates that repeated ICM exposure and large ICM volumes are more likely to elevate the risk of thyroid disorders [13,14]. Contrary to these studies, we found no correlation between contrast volume and thyroid hormone dysregulation.…”

Trends of CT utilisation in an emergency department in Taiwan: a 5-year retrospective study

“…Third, senior physicians should audit the orders of CT scans by junior physicians in the ED. 17 27 28 …”

2021 European Thyroid Association Guidelines for the Management of Iodine-Based Contrast Media-Induced Thyroid Dysfunction

“…A significantly higher risk of ICM-induced TD (based on International Classification of Diseases, Ninth Revision, Clinical Modification codes) was demonstrated in Taiwan among 1 million patients in the general population over a single year time period; the adjusted hazard ratio (HR) of Hyper and Hypo compared with controls was 1.22 (95% CI, 1.04–1.44) and 2.00 (95% CI, 1.65–2.44), respectively [14]. Moreover repeated ICM exposure (>1 time of ICM per year) increased significantly the risk of thyroid disorders (HR = 3.04; 95% CI, 2.47–3.73) [15]. A subsequent study using the Taiwan’s National Health Insurance Research Database found that patients with euthyroid nodular goiter had almost 5-fold higher risk of ICM-induced TD than patients without thyroid nodule(s), including Hyper (HR 5.77, CI 2.64–12.62) and Hypo (HR 4.95, CI 2.15–11.40) [16].…”