Abstract
We report hypothyroidism induced by a closed cap containing povidone-iodine in a 32-year-old female undergoing nightly peritoneal dialysis (NPD). The patient's thyroid became enlarged after switching from continuous ambulatory peritoneal dialysis to NPD in June 1994. In July 1995, the patient's serum thyroid stimulating hormone (TSH) level was found to be markedly elevated to 121μU/ml, and her serum free triiodothyronine (FT3) and free thyroxine (FT4) levels were 2.6 pg/ml and 0.4ng/dl, respectively. Thyroid 3-hour radioactive iodine uptake was high. Serum inorganic iodine (II) was elevated to 15.0μg/dl. Antithyroid antibodies including antibodies to thyroglobulin, thyroid peroxidase and TSH receptor were all negative. Histologically, neither lymphocytic infiltration nor fibrosis in the interfollicular space suggestive of chronic thyroiditis was detected. Based on these findings a diagnosis of reversible hypothyroidism induced by iodine excess was made, but strict dietary iodine restriction did not decrease the patient's serum II or TSH levels. During the first infusion of dialysate in NPD, the povidone-iodine that leaks out from a closed cap flows into the peritoneal cavity because of the absence of peritoneal effluents. Preventing the flow of povidone-iodine decreased serum II and TSH levels to 4.6μg/dl and 28.0μU/ml, respectively. Thus, attention should be directed to the complication of hypothyroidism induced by povidone-iodine-containing closed caps in patients undergoing NPD.
