Effects of contrast media on renaI and thyroid function - and the impact of thyroid nodules

Abstract

The risk of renal damage by iodine contrast media (ICM) has long been discussed but there is still controversy about whether contrast-induced acute kidney injury (CI-AKI) exists. ICM-induced thyroid dysfunction is a less known adverse effect and possible risk factors include presence of thyroid nodules that may be found incidentally. A major concern is which incidental thyroid nodules that must undergo further investigation. The EU-TIRADS was presented in 2017 to facilitate differentiation between benign and malignant lesions and to help decide when fine needle aspiration (FNA) may be omitted. This had not yet been validated with RCT. Aims: I) To prospectively assess ICM effects on renal function in 1009 individuals, to compare ICM effects on serum creatinine (sCr) with normal intraindividual sCr fluctuation and find possible risk factors for CI-AKI. II) To prospectively study ICM effects on thyroid function in 448 individuals, assess the clinical relevance of ICM-induced hormonal changes, and search for related risk factors. III) To determine the prevalence of thyroid lesions when screening a randomly selected cohort with thyroid ultrasound (US) and evaluate the need of subsequent follow-up. Also, to compare thyroid nodule detection capacity between US and CT. IV) To compare selective vs non-selective fine needle aspiration (FNA) of thyroid nodules in a randomized study of patients (n=195) with thyroid nodules. Results: In Paper I, there was a low incidence of CI-AKI (1.2%), even lower when applying the updated ESUR criteria (0.2%). Possible risk factors, e.g. diabetes, low eGFR, NSAID use, were not associated with CI-AKI. ICM were also safe regarding effects on thyroid function (Paper II) with no cases of ICM-induced overt hypo- or hyperthyroidism and no statistically significant effects on thyroid-related symptoms. Elevated TPO-antibodies and being born outside of Sweden were associated with developing subclinical hypothyroidism. Thyroid US screening of 542 individuals (Paper III) rendered one case of thyroid malignancy but the amount of follow-up was substantial, with 8% requiring further follow-up. US was superior to CT in thyroid lesion detection. Paper IV showed higher percentage of high Bethesda cytology results in patients undergoing FNA with selection by EU-TIRADS compared to the group where non-selective FNA was performed. Conclusions: Administration of ICM to a randomly selected cohort, 50-65 years of age, with normal to moderately reduced renal function was safe, both in terms of renal and thyroid function. Thyroid US screening renders a non-negligible amount of clinical follow-up and considered to be of low cost-effectiveness. Practicing selective cytology, using EU-TIRADS, was safe in terms of risks of missing malignancy but did not decrease the numbers of FNAs substantially.