THYROID ADAPTATION TO CHRONIC TETRAGLYCINE HYDROPERIODIDE WATER-PURIFICATION TABLET USE

Tetraglycine hydroperiodide tablets purify water by liberating 8 mg fr ee iodine/tablet. The effects of ingesting four tablets daily for 3 mo nths on thyroid size, function, and radioactive iodine uptake were stu died prospectively in eight healthy volunteers. Serum inorganic iodide increased from 2.7 to approldmately 100 mu g/dL. Urinary iodide excre tion rose 150-fold from a pretreatment mean of 0.276 to 40 mg/day. Rad ioactive iodine uptake was less than 2% after 7 days and remained belo w 2% in all subjects at 90 days. Mean serum T-4 and T-3 declined after 7 days. T-4 remained below baseline, whereas T-3 had recovered by the end of the treatment period. Serum TSH and the TSH response to TRH ro se significantly after 7 days and remained elevated at 3 months. The a verage thyroid volume, determined by ultrasound, increased by 37%. Nei ther hyperthyroidism nor hypothyroidism was observed. The mean thyroid volume in seven subjects available for repeat determinations an avera ge of 7.1 months after the study was not different from the baseline v alue. In normal subjects, a reversible TSH-dependent thyroid enlargeme nt occurs in response to the iodine load from daily use of tetraglycin e hydroperiodide water purification tablets.