Endocrine Abstracts

Introduction: In thyrotoxicosis, the clinical syndrome of excess circulating thyroid hormones, differentiation must be made between thyrotoxicosis with increased or decreased radio-iodine tracer uptake on thyroid scintigraphy. A cause of thyrotoxicosis with decreased radio-iodine uptake is iodine excess. In patients not taking any medication and without any history of recent radiological imaging studies, the confirmation of iodine excess as the cause of the thyrotoxicosis is difficult. Especially in patients with a penchant for traditional medicine and natural supplements, a thorough inquiry about supplement use is key to establishing a correct diagnosis.

Case Presentation: In our endocrinology outpatient clinic, in the period between September 2017 and October 2021, six patients, originally from Western Africa, were referred due to abnormal thyroid function tests with suppressed TSH and elevated fT3 and/or fT4. In all patients thyroid antibodies were negative. No fever, painful swelling of the thyroid or recent URTI were reported. The patients hadn’t used any medication containing iodine nor had recently underwent a radiological study. On thyroid scintigraphy, in all patients a reduced to absent radio-iodine uptake could be seen. Ultimately, it came to light that all six patients had been taking African natural supplements. In one patient a complete 24-h urinary iodine excretion was performed, which was significantly elevated with a value of 1115.8 μg iodine per 24 hours (783 μg/l), confirming iodine excess. After discontinuation of the supplements, in all patients a normalization of the thyroid function tests could be seen.

Discussion/conclusion: Some herbal remedies used in traditional African medicine seem to cause hyperthyroidism. Characteristics of this kind of hyperthyroidism are reduced to absent radio-iodine uptake on thyroid scintigraphy, absent thyroid autoimmunity, a normal thyroid ultrasound and a spontaneous restoration of euthyroid state with discontinuation of the supplements. Our hypothesis is that this type of thyrotoxicosis is caused by an increased iodine exposure due to use of natural supplements used in traditional African medicine. We suspect that the African supplements, imported from Western Africa to Europe, are treated with iodine-containing compounds to improve the preservability. Iodine-induced hyperthyroidism, or the Jod-Basedow syndrome, is therefore a cause of thyrotoxicosis that therefore must certainly be kept in mind in certain ethnic groups. If a thorough questioning of the supplement use doesn’t reveal the intake of natural remedies, then an urinary iodine excretion can sometimes provide a conclusive answer if iodine excess is suspectedly involved in the thyrotoxicosis.