Abstract
Serum creatine kinase (CK) elevation can occur in some patients with Graves’
disease treated with antithyroid drugs (ATDs). This study retrospectively
investigated clinical characteristics and biochemical data of patients with
Graves’ disease who experienced serum CK elevation during ATD treatment. CK
elevation was observed in 29.6% (37/125) of patients, with 11.2% (14/125) being
symptomatic. This incidence is higher than previously reported (13.5%). There
were no differences in pre-treatment characteristics between patients with and
without CK elevation. The intervals between the initiation of ATD treatment or
normalization of thyroid function and the onset of CK elevation were 11.3±8.0
and 5.8±6.6 weeks, respectively, and peak serum CK levels averaged 441.9±394.0
IU/l. Markedly elevated serum CK were accompanied by increased serum myoglobin
levels. Serum CK elevation occurred either continuously or intermittently, or as
a single episode during the course of treatment. Thyroid function at the time of
CK elevation varied from hyperthyroid to normal to hypothyroid. In conclusion,
serum CK elevation in patients with Graves’ disease treated with ATDs is not
uncommon, with symptomatic cases accounting for approximately 10%, and the
frequency increasing to around 30% when asymptomatic cases are included. The
characteristics observed in our patients suggest the involvement of alternative,
as yet unknown mechanisms beyond the relative hypothyroidism theory and the ATD
side-effect theory in the development of CK elevation during ATD treatment in
patients with Graves’ disease.
Keywords
myoglobin - muscle - treatment
