Increased soluble IL-2 receptor levels in serum from a patient with painless thyroiditis

CONTEXT: Serum concentration of soluble interleukin-2 receptor (sIL-2R) has been established as a reliable marker of T-lymphocyte activation. However, there have been no reports describing the relationship between serum sIL-2R and painless thyroiditis. OBJECTIVE: We report a case of a 76-yr-old female with a significant and temporary increase of sIL-2R concomitant with painless thyroiditis. CASE ILLUSTRATION: The patient was diagnosed with malignant lymphoma at the age of 73. After 6 cycles of CHOP-R complete remission was induced and no recurrence was observed up to 3.5 years. At 76 years of age, she exhibited hyperthyroidism and was diagnosed with painless thyroiditis based upon US examination and (99m)Tc-Thyroid scintigraphy. Her AST and ALT were mildly elevated, and her serum level of sIL-2R increased up to 2230 U/mL from the approximately 540 U/mL, which had been stable for 3 years before. These abnormal data normalized without requiring any treatment. The time-course of the reduction in sIL-2R did not correlate with FT4 or FT3, but was very similar to that of AST and ALT. CONCLUSION: There was no evidence of relapse of the malignant lymphoma. We conclude that the increase of sIL-2R was associated with painless thyroiditis. Considering the similar time-course between the reduction of serum sIL-2R and those of AST and ALT, which are often accompanied by autoimmune processes in painless thyroiditis during the development of hyperthyroidism, it was suggested that the increase of serum sIL-2R in this case resulted from activation of an autoimmune process.