Spontaneous hypothyroidism in the follow up of Graves hyperthyroid patients treated with antithyroid drugs.
OBJECTIVE
Spontaneous hypothyroidism may follow the natural course of Graves disease (GD) after treatment with antithyroid drugs (ATD).


METHODS
We studied retrospectively 139 remitted Graves hyperthyroid patients treated with ATD, with a follow-up period of 17.5 years (range 6 to 25 years). Elevated serum concentration of thyroid-stimulating hormone and low serum thyroxine concentrations confirmed the diagnosis.


RESULTS
Thirteen patients (median age, 41 years; 26 to 48 years) developed spontaneous hypothyroidism, 4 to 144 months (median, 48 months ) following withdrawal of ATD. The prevalence of hypothyroidism was 9.3% and the incidence was 2.3% per year (13/ 563.6 patients/year of observation). There was no association with types of drugs used or the regimens. Spontaneous hypothyroid patients showed elevated titers (P = 0.02) of serum antithyroid peroxidase antibody (TPOAb) at the end of treatment with ATD, compared with the titers found at the beginning. These patients also had higher titers of TPOAb (P = 0.01) in relation to euthyroid patients. In contrast, the changes in serum antithyroglobulin antibody titers were not significant.


CONCLUSIONS
Because of the shift from euthyroidism to spontaneous hypothyroidism, GD patients demanded a strict follow up after ATD therapy. It seems that there is an effect of TPOAb on thyroid destruction.
De Moraes
Adriana V C
AV
Service of Endocrinology, Hospital Servidor Público Estadual, Iamspe, São Paulo, Brazil.
Pedro
Ana Beatriz P
AB
Romaldini
João H
JH
D000293:Adolescent; D000328:Adult; D000368:Aged; D013956:Antithyroid Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood; D015415:Biomarkers / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006111:Graves Disease / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000276:immunology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors
D013956:Antithyroid Agents; D001323:Autoantibodies; D015415:Biomarkers; C006606:anti-thyroglobulin; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine