Long-term interferon beta-1b therapy for MS: is routine thyroid assessment always useful?
BACKGROUND
The authors previously reported on the development of thyroid dysfunction and autoimmunity during 1-year treatment of patients with MS with interferon-beta 1b (IFN beta-1b).


OBJECTIVE
To evaluate the evolution of incident thyroid disease and the possible development of more thyroid disease during longer term therapy.


METHODS
The authors studied 31 patients (aged 34 +/- 7 years; 21 women) with relapsing-remitting MS during 3 years of IFN beta-1b treatment. Systematic thyroid assessment was performed every 3 or 6 months, depending on the development of thyroid disease.


RESULTS
After the first year of IFN beta-1b treatment, no further cases of thyroid disease were observed. Among the six patients with early incident subclinical hypothyroidism, thyroid dysfunction persisted only in those with baseline autoimmune thyroiditis (n = 2). The three patients who developed transient hyperthyroidism remained euthyroid throughout the treatment course. A positive autoantibody titer was continually detected in only two out of five patients without baseline autoimmunity.


CONCLUSIONS
The risk of thyroid disease seems related to IFN beta-1b treatment during the first year only, particularly in patients with preexisting thyroiditis. Furthermore, incident thyroid dysfunction is generally transient and mild in degree. Indeed, we recommend a routine systematic thyroid assessment only in patients with baseline thyroiditis. During the first year of therapy, serum thyroid-stimulating hormone measurement should suffice as first line test; a systematic thyroid assessment is only useful for those patients with incidental and persistent dysfunction. Further studies with many patients will be necessary to confirm our suggestions as broad clinical guidelines.
Monzani
F
F
Department of Internal Medicine, University of Pisa School of Medicine, Italy.
Caraccio
N
N
Casolaro
A
A
Lombardo
F
F
Moscato
G
G
Murri
L
L
Ferrannini
E
E
Meucci
G
G
D000328:Adult; D001323:Autoantibodies / Q000097:blood; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D000068556:Interferon beta-1a; D000068576:Interferon beta-1b; D016899:Interferon-beta / Q000008:administration & dosage / Q000009:adverse effects*; D007453:Iodide Peroxidase / Q000276:immunology; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D018570:Risk Assessment; D013954:Thyroglobulin / Q000097:blood; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000187:drug effects; D013967:Thyroiditis, Autoimmune / Q000097:blood / Q000175:diagnosis* / Q000209:etiology*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013995:Time; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood; D014463:Ultrasonography
D001323:Autoantibodies; C006606:anti-thyroglobulin; D014284:Triiodothyronine; D000068576:Interferon beta-1b; D016899:Interferon-beta; D013972:Thyrotropin; D013954:Thyroglobulin; D007453:Iodide Peroxidase; D013974:Thyroxine; D000068556:Interferon beta-1a