Benefit of short-term iodide supplementation to antithyroid drug treatment of thyrotoxicosis due to Graves' disease.
OBJECTIVE
Combined treatment with anti-thyroid drugs (ATDs) and potassium iodide (KI) has been used only for severe thyrotoxicosis or as a pretreatment before urgent thyroidectomy in patients with Graves' disease. We compared methimazole (MMI) treatment with MMI + KI treatment in terms of rapid normalization of thyroid hormones during the early phase and examined the later induction of disease remission.


METHODS
A total of 134 untreated patients with Graves' disease were randomly assigned to one of four regimens: Group 1, MMI 30 mg; Group 2, MMI 30 mg + KI; Group 3, MMI 15 mg and Group 4, MMI 15 mg + KI. For easy handling, KI tablets were used instead of saturated solution of KI. KI was discontinued when patients showed normal free thyroxine (FT4) levels but MMI was continued with a tapering dosage until remission. Remission rate was examined during a 4- to 5-year observation.


METHODS
Serum FT4, FT3 and TSH were measured by chemiluminescent immunoassays. TSH receptor antibody (TRAb) was assayed with TRAb-ELISA. Goitre size was estimated by ultrasonography.


RESULTS
After 2 weeks of treatment, normal FT4 was observed in 29% of patients in Group 1 and 59% (P < 0.05) of patients in Group 2. Furthermore, normal FT4 after 2 weeks of treatment was observed in 27% of patients in Group 3 and 54% (P < 0.05) of patients in Group 4. Similarly, FT3 normalized more rapidly in Groups 2 and 4 than in Groups 1 and 3. None of the patients showed an increase in thyroid hormones or aggravation of disease during combined treatment with MMI and KI. The remission rates in Groups 1, 2, 3 and 4 were 34%, 44%, 33% and 51%, respectively, and were higher in the groups receiving combined therapy but differences among four groups did not reach significance.


CONCLUSIONS
Combined treatment with MMI and KI improved the short-term control of Graves' hyperthyroidism and was not associated with worsening hyperthyroidism or induction of thionamide resistance.
Takata
Kazuna
K
Kuma Hospital, Kobe, Japan. takata@kuma-h.or.jp
Amino
Nobuyuki
N
Kubota
Sumihisa
S
Sasaki
Ichiro
I
Nishihara
Eijun
E
Kudo
Takumi
T
Ito
Mitsuru
M
Fukata
Shuji
S
Miyauchi
Akira
A
D000328:Adult; D013956:Antithyroid Agents / Q000008:administration & dosage* / Q000009:adverse effects; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D005260:Female; D006111:Graves Disease / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008713:Methimazole / Q000008:administration & dosage / Q000009:adverse effects; D008875:Middle Aged; D011193:Potassium Iodide / Q000008:administration & dosage* / Q000009:adverse effects; D012074:Remission Induction; D018570:Risk Assessment; D013960:Thyroid Function Tests; D013963:Thyroid Hormones / Q000097:blood; D013971:Thyrotoxicosis / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
D013956:Antithyroid Agents; D013963:Thyroid Hormones; D011193:Potassium Iodide; D008713:Methimazole