“Fueling the Fire” - Irish Sea-Moss Resulting in Jod-Basedow Phenomenon in a Patient With Grave’s Disease

Abstract

Background: Jod-Basedow phenomenon is a rare cause of thyrotoxicosis due to excess iodine intake. Herbal supplements containing sea-moss have high iodine amount which may precipitate thyrotoxicosis in patients with underlying Grave’s disease or autonomous thyroid nodules. Clinical Case: A seemingly healthy 28-year-old female presented to the ED with chief complaint of fatigue with associated anxiety, palpitations and weight loss. On admission her temperature was 100.4 F, pulse 126 bpm and blood pressure 116/56 mmHg. Exam was unremarkable for thyroid goiter or orbitopathy. Labs revealed WBC count 3.4 x103/µL (ref range 4.0-11.0) with neutropenia, hemoglobin 4.3 g/dL (11.7-15.7), platelet 49 x103/µL (150-450). Liver transaminases (AST, ALT, and alkaline phosphatase) were elevated with levels up to 4 times the upper limit of normal. She was diagnosed with hemolytic anemia secondary to severe Vitamin B12 deficiency due to pernicious anemia. TSH was <0.01 mIU/L (0.27-4.20), free T4 2.46 ng/dL (0.8-1.9) and total T3 139 ng/dL (76-181). The patient subsequently endorsed remote history of hyperthyroidism diagnosed 7 years ago however she could not recall the underlying etiology or the name of medication she was treated with. She reportedly stopped this medication after 1 month due to developing goiter. She also endorsed intermittent use of store-bought supplement of Irish sea moss and bladderwrack in last 2 years. Further workup revealed elevated TSI and TBII antibody titers establishing diagnosis of Grave’s disease. Thyroid ultrasound showed normal sized heterogeneous hypervascular gland with no nodules. I-123 thyroid uptake and scan showed diffuse moderately elevated radioiodine uptake of 16.8% and 40.8% at 4 and 24 hours, respectively. Thionamide therapy was withheld due to concern of neutropenia and transaminitis. She was treated with beta-blocker after which her vital signs normalized. Labs 1 week after stopping sea moss showed TSH 0.01 mIU/L and free T4 1.4 ng/dL. Conclusion: Irish sea moss is a readily available herbal supplement with high, variable amounts of iodine. Despite little scientific evidence, it is often marketed to improve goiter amongst other health benefits. The recommended daily iodine intake per the FDA is 150 mcg. Higher amounts are expected to initially cause a short-lived suppression of thyroid function; the Wolff-Chaikoff effect, followed by “escape” and accelerated production of thyroid hormone in abnormal thyroid gland, known as Jod-Basedow phenomenon. In our case, the patient unknowingly worsened her underlying Grave’s disease due to the Jod-Basedow effect. Of note, apparantly she had a longer than expected course of Wolff-Chaikoff effect preceding the thyrotoxic state due to sporadic irregular intake of sea moss. Discontinuing sea moss led to clinical and biochemical improvement of hyperthyroidism without requiring thionamide therapy.