Ann Pediatr Endocrinol Metab.  2015 Jun;20(2):106-109. 10.6065/apem.2015.20.2.106.

Elevation of serum creatine kinase during methimazole treatment of Graves disease in a 13-year-old girl and a literature review of similar cases

• Kim H
• Kim J
• Huh R
• Cho SY
• Jin DK

• KMID: 2368995
• DOI: http://doi.org/10.6065/apem.2015.20.2.106

Abstract

We report a 13-year-old girl with Graves disease, who showed an increased level of serum creatine kinase (CK) accompanied by myalgia after methimazole (MMI) treatment. This patient developed muscular pain two weeks after MMI administration, along with increased CK levels. The level of thyroid hormone was within the normal range when she showed increased CK levels. After the MMI dose was decreased and levo-thyroxine was added, serum CK levels decreased to normal and the myalgia improved. The pathophysiologic mechanism of this effect has not yet been elucidated. An acute relatively hypothyroid state occurs secondary to antithyroid drug (ATD) administration in chronic hyperthyroidism, which may cause changes in the CK levels. In this report, we present a rare pediatric case, along with a literature review of similar cases. In the initial state of MMI treatment, myalgia should be detected and when it occurs, CK levels should be measured. The clinical strategy of monitoring CK levels with the aim of normalizing thyroid hormones is helpful in case of the development of adverse reactions, such as myalgia, during ATD treatment for Graves disease in children.

Keyword

Graves disease; Antithyroid drugs; Methimazole; Creatine kinase; Myalgia

MeSH Terms

Adolescent*
Antithyroid Agents
Child
Creatine Kinase*
Female
Graves Disease*
Humans
Hyperthyroidism
Methimazole*
Myalgia
Reference Values
Thyroid Gland
Thyroid Hormones
Antithyroid Agents
Creatine Kinase
Methimazole
Thyroid Hormones

Figure

• 

  Fig. 1 Serum concentrations of both TSH and fT4 with the common logarithms of the CK level (log CK). Logarithmic scales were used to graph TSH, fT4, and CK levels. Horizontal axis: the extended month after the diagnosis of Graves disease. TSH, thyroid-stimulating hormone; fT4, free thyroxine; CK, creatine kinase; RR, reference range; MMI, methimazole.

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