The prevalence of transient thyrotoxicosis after antithyroid drug therapy in patients with Graves' disease.
BACKGROUND
Although transient thyrotoxicosis occurring after antithyroid drug (ATD) withdrawal in patients with Graves' hyperthyroidism has been reported, the prevalence of transient thyrotoxicosis after ATD therapy is as yet unknown. When patients with transient hyperthyroidism are mistakenly regarded as recurrences, they receive unnecessary therapy. The aim of this study was to investigate the prevalence of transient thyrotoxicosis after ATD withdrawal.


METHODS
We selected 110 consecutive patients with Graves' disease whose ATD therapy was stopped from December 2002 to September 2004 prospectively. Patients were observed for more than 1 year after ATD withdrawal, and 12 patients dropped out. Serum levels of free thyroxine (FT(4)), thyrotropin, and thyrotropin-binding inhibitor immunoglobulin were measured at ATD withdrawal, and 3, 6, and 12 months after withdrawal. When the patients showed mild thyrotoxicosis (serum FT(4) level of less than 3.00 ng/dL), we followed them up for 1 month without medication.


RESULTS
The remission rate of the study group was 61.8% (68/110). Twenty-eight patients became euthyroid after transient thyrotoxicosis, equivalent to 41.2% of the remission patients. Eight of 28 patients showed overt thyrotoxicosis, and the rest subclinical thyrotoxicosis. Transient thyrotoxicosis occurred mostly 3-6 months after ATD withdrawal.


CONCLUSIONS
Transient thyrotoxicosis after ATD withdrawal in patients with Graves' disease is not a rare phenomenon. Clinicians should be aware that the recurrence of Graves' disease after the withdrawal of ATD may be transient.
Kubota
Sumihisa
S
Kuma Hospital, 8-2-35, Shimoyamate-dori, Chuo-ku, Kobe 650-0011, Japan. kubota@kuma-h.or.jp
Takata
Kazuna
K
Arishima
Takeshi
T
Ohye
Hidemi
H
Nishihara
Eijun
E
Kudo
Takumi
T
Ito
Mitsuru
M
Fukata
Shuji
S
Amino
Nobuyuki
N
Miyauchi
Akira
A
D000328:Adult; D013956:Antithyroid Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006111:Graves Disease / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating; D008297:Male; D008713:Methimazole / Q000009:adverse effects* / Q000627:therapeutic use; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012008:Recurrence; D013375:Substance Withdrawal Syndrome; D013971:Thyrotoxicosis / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors
D013956:Antithyroid Agents; D001323:Autoantibodies; D018828:Immunoglobulins, Thyroid-Stimulating; C094372:thyrotropin-binding inhibitory immunoglobulin; D008713:Methimazole; D013972:Thyrotropin; D013974:Thyroxine