Urinary Iodine Clearance following Iodinated Contrast Administration: A Comparison of Euthyroid and Postthyroidectomy Subjects

Abstract

Purpose. To compare iodine clearance following iodinated contrast administration in thyroidectomised thyroid cancer patients and euthyroid individuals. Methods. A convenience population (6 thyroidectomised thyroid cancer patients and 7 euthyroid controls) was drawn from patients referred for iodinated contrast-enhanced computed tomography (CT) studies. Subjects had sequential urine samples collected up to 6 months (50 samples from the thyroidectomised and 63 samples from the euthyroid groups). t-tests and generalised estimating equations (GEE) were used to test for group differences in urinary iodine creatinine ratios. Results. Groups had similar urinary iodine creatinine ratios at baseline, with a large increase 2 weeks following iodinated contrast (P = 0.005). Both groups had a return of urinary iodine creatinine ratios to baseline by 4 weeks, with no significant group differences overall or at any time point. Conclusions. Thyroidectomised patients did not have a significantly different urinary iodine clearance than euthyroid individuals following administration of iodinated contrast. Both had a return of urinary iodine creatinine ratios to baseline within 4 weeks.

Performance of CT in the Preoperative Diagnosis of Cervical Lymph Node Metastasis in Patients with Papillary Thyroid Cancer: A Systematic Review and Meta-Analysis

“…However, several recent studies have reported the supposition that the delay of radioiodine therapy was not necessary in patients who underwent contrast-enhanced CT because the iodine is generally cleared within 4 -8 weeks in most patients, and the body iodine content is not an essential determinant of thyroid ablation. [37][38][39][40][41] Therefore, the benefit gained from improved anatomic imaging generally outweighs any potential risk regarding a several-week delay in radioactive iodine imaging or therapy.…”

Urinary Iodine Excretion and Serum Thyroid Function in Adults After Iodinated Contrast Administration

“…There have been only a few studies assessing the rate of urinary iodine clearance after radiographic iodinated contrast administration (20)(21)(22)(23). The interest in the rate of urinary iodine clearance after ICM administration has been primarily for the timing of radioactive iodine ablation after thyroidectomy for thyroid cancer and for treating patients with hyperthyroidism with radioactive iodine.…”

“…Most recently, Ho et al compared urinary iodine clearance between six athyreoitic patients and seven euthyroid controls in Canada, measuring urinary iodine clearance every two weeks for the first eight weeks, then monthly up to six months after CT scan with iodinated contrast. They found that urinary iodine clearance returned to baseline by four weeks, without any significance differences between the two groups (23). Iodine nutrition varies by region of the world, and iodine deficiency confers an additional risk for the development of thyroid dysfunction following iodine excess.…”

Ultrasonography Diagnosis and Imaging-Based Management of Thyroid Nodules: Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations

“…Contrast-enhanced CT has not been routinely applied for the preoperative evaluation of thyroid cancer, and the use of iodine-based contrast media was strictly restricted before surgery because of the concerns over the disturbed radioactive iodine uptake for months and the delay of radioiodine treatment ( 177 178 ). However, recent studies have demonstrated that the delaying of the radioiodine therapy is not necessary in the patients who have undergone preoperative contrast-enhanced CT, and that the body iodine content is not an important determinant of thyroid ablation ( 179 180 181 182 183 ). Contrast-enhanced CT has a complementary role in the preoperative assessment of the extent of the primary tumors and nodal metastases ( 184 185 186 , 187 188 ).…”