Inadvertent Iodine Excess Causing Thyrotoxic Hypokalemic Periodic Paralysis

The recent interesting article by Ohye et al¹ addressed the continuing problem of nonprescribed and occult medication use. I applaud the scientific dedication of the 2 lead authors who took it upon themselves to ingest the implicated tablets, which have been analyzed to contain portions of tetraiodothyronine (T₄) and triiodothyronine (T₃). Most would have been convinced without the need to take this extra step, which is unnecessary for 2 reasons. The first is that data on the pharmacokinetic of T₃ and T₄ are well established.² The 34 μg to 45 μg of T₄ would have few biological effects owing to the binding of T₄ to circulating proteins. As the half-life of T₄ is 7 to 10 days, a good 4 to 6 weeks of consistent T₄ ingestion would need to occur to ensure a therapeutic level. The elevated T₃ level is consistent with its short half-life, and the dose approximates that used therapeutically. Thus, its transient use is reflected biologically in a mild reduction in thyroid-stimulating hormone level. The second reason is the effect of self-testing, which may unmask other unheralded medical conditions, particularly that which is specific to my and the authors’ heritage. This is best highlighted in the following clinical vignette.