Premium
The effect of iodide on serum thyroid hormone levels in normal persons, in hyperthyroid patients, and in hypothyroid patients on thyroxine replacement *
Author(s) -
Phillppou George,
Koutras Demetrios A.,
Plperlngos Gregory,
Souvatzoglou Athanasslos,
Moulopoulos Spyrldon D.
Publication year - 1992
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1992.tb02267.x
Subject(s) - medicine , endocrinology , hormone , thyroid , iodine , globulin , iodide , triiodothyronine , thyroxine binding globulin , reverse triiodothyronine , chemistry , organic chemistry
OBJECTIVE To clarify the duration and the extent of the antithyroid effect of lodides In hyperthyroldlsm, and to Investigate whether Iodides have an additional perlpheral effect on the metabollsm of thyrold hormones, as has been reported for some organic IodIne compounds. DESIGN The effect on the perIpheral thyroId hormone levels of 150 mg of potassIum Iodide dally (equIvalent to 114 mg of IodIde) foro 3–7 weeks was compared In 21 hyperthyroId patients and 12 healthy controls. A possible effect of IodIde on the perIpheral metabollsm of thyroId hormones was Investigated by assessing the serum levels of thyroid hormone In 12 hypothyroid patients on thyroxine replacement for 2 weeks. PATIENTS There were 21 thyrotoxic patients, 12 healthy hospital controls, and 12 patients with complete or near‐complete hypothyroldlsm, on thyroxine replacement. MEASUREMENTS The following were measured before and at weekly intervals after Iodide administration: (1) pulse rate, (2) serum T4, (3) serum T3, (4) serum TSH, (5) serum thyroxlne‐binding capacity (TBC), (6) serum rT3, (7) serum thyroxine‐binding globulln (TBG), (8) the free‐T4 Index, calculated as T4/TBC. RESULTS In the hyperthyroid patients serum T4, T3 and rT3 decreased, whereas serum thyroxlne‐binding globulin and thyroxine binding capacity Increased. Serum T3, however, did not become completely normal In all cases. After 21 days, serum T4 and T3 started Increasing again in some cases, but other patients remained outhyrold even after 6 weeks. In the normal controls there was a small but significant and consistent decrease In serum T4, T3 and rT3 and an Increase In serum TSH. Finally, In the T4‐treated hypothyroid patients there was no consistent change, except for an Increase of serum T4 at 1 and 14 days and a decrease of serum TSH the first day. CONCLUSION Iodides in hyperthyroldlsm have a variable and unpredictable Intensity and duration of antlthyrold effect. Their antithyroid effect Is smaller In normal controls. They have no Important effect on the peripheral metabolism of thyroid hormones.