To the Editor.—
We report a case of erythema nodosum treated with potassium iodide with the development of profound hypothyroidism secondary to exogenous intake of iodide. It is known that the prolonged use of iodides can lead to hypothyroidism, termed the Wolff-Chaikoff effect.1,2 Clinicians should be alert for signs and symptoms of hypothyroidism while treating patients with potassium iodide.
Report of a Case.—
A 67-year-old woman was seen in April 1986 with tender red nodules located mainly on the anterior surfaces of the legs. A biopsy specimen of one of the nodules showed a septal panniculitis consistent with erythema nodosum. Medications included insulin, prazosin hydrochloride, hydrochlorothiazide, potassium, and metaproterenol sulfate, none of which were recently started. Workup included chest roentgenogram, tuberculin skin test, chemistry profile, complete blood cell count, rapid plasma reagin, urinalysis, antistreptolysin-O titer, and antinuclear antibody, all of which showed negative or unremarkable results. The patient
Johnson TM, Rapini RP. The Wolff-Chaikoff Effect: Hypothyroidism due to Potassium Iodide. Arch Dermatol. 1988;124(8):1184-1185. doi:10.1001/archderm.1988.01670080010005