Iodine-Induced Hyperthyroidism—An Old Clinical Entity That Is Still Relevant to Daily ICU Practice: A Case Report

Abstract

Objective. Hyperthyroidism has been described as elevated serum free T3 and/or free T4 levels with decreased thyrotropin (TSH) concentrations. The main causes are related to autoimmune and neoplastic pathology. However, it might be caused due to a long-term topical exposure (iodine solution dressing) or by intravenous administration of iodine-containing substances. Both clinical and laboratory features might be presented. The main management is based on interruption of all exposures with iodine solutions and also antithyroid medicine in case of severe laboratory and clinical disturbances. Data Sources. We present a case of iodine-induced hyperthyroidism in a critically ill ICU patient caused by excessive iodine containing antiseptic solution washes and contrast agent administration. The patient was successfully treated by discontinuing iodine exposure and beta-blocker administration. Conclusions. In patients with underlying thyroid gland pathology, thyroid-function tests and clinical observation in the ICU are of critical importance.

Iodine in commercial edible iodized salts and assessment of iodine exposure in Sri Lanka

“…IDD contains a collection of functional and developmental abnormalities such as endemic goiter, abortions, still births, cretinism, retarded physical development, brain damage and irreversible mental retardation [ 1 – 3 ]. Excessive iodine intake from food and water can also have adverse chronic health effect such as Iodine Induced Hyperthyroidism (IIH), thyroiditis, goiter, thyroid papillary cancer and thyrotoxicosis" [ 5 – 8 ]. Long term excessive iodine intake increases the activity of Thyroid Stimulating Hormone (TSH) and reduces thyroid hormone production, through loss of the "escape" phenomenon after the Wolff-Chaikoff effect (inhibits organification in the thyroid gland, the formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream) resulting in low thyroid hormone levels, or hypothyroidism in fetuses and newborns [ 9 ].…”

The dangers of iodine-based contrasts in an elderly patient with thyroid disease

“…Early studies in the 1920s suggested that as many as 12% of new-onset hyperthyroid cases could be attributed to the administration of exogenous iodine for treatment of endemic goitre 10. Case study evidence has identified that this can be triggered from a wide range of iodine loads, even from systemic absorption of topical iodine-based agents used in wound cleaning 4. Although the typical iodine load following use of intravenous contrast varies depending on the procedure and the exact contrast agent, a typical dose is ∼13 500 µg of free I − (iodide) and 15–60 g of bound iodine 11 12.…”

“…Iodine loads in the form of oral supplements,3 skin preparations,4 iodine-containing medications such as amiodarone5 and intravenous contrast agents6 have a well-documented potential to trigger thyrotoxicosis in susceptible patient groups, such as the elderly and those with pre-existing thyroid disease.…”

Dietary iodine intake, thyroid diseases and the prevalence of papillary carcinoma (PTC)

“…The recommended iodine daily allowance of 70-150 µg [35].An excess of iodine through dietary intake, drugs or other iodine-containing compounds can lead to goiter [36][37], hyperthyroidism [38][39][40][41][42][43][44][45], hashimoto's thyroiditis [46] and thyrotoxicosis [47][48][49][50][51][52][53][54] through increasing thyroid hormone synthesis in the presence of underlying thyroid disease, particularly multinodular goiters containing previously existing area of autonomous function. In 1958, Introduction of potassium iodide (KI) in order to the prevention of goiter in French, many students developed iodine goiter with oral high dosage of 1% KI or 10mg KI daily.…”

“…Excessive iodine intake might also be due to a long-term topical exposure (iodine solution dressing or topical iodine application) or by intravenous administration of iodine-containing substances [39,41,45,58]. In a classical study, four euthyroid patients with a single autonomous nodule from the slightly iodine-deficient Brussels region received a supplement of 500ug iodine per day.…”