Lithium-associated thyroiditis.

OBJECTIVE

To report an unusual case of thyrotoxicosis caused by "silent thyroiditis" in a lithium-treated patient and to summarize all prior case reports of lithium-associated thyroiditis and compare them with our current case.

METHODS

In addition to reporting our case, we undertook a MEDLINE search of all case reports of lithium-associated thyroiditis from 1978 until the present. All reported cases of lithium-associated thyroiditis must have had documented low thyroid radioiodine uptake to be included.

RESULTS

A 52-year-old man with a history of bipolar disorder, who had been treated with lithium carbonate for 15 years, was admitted because of delusional mania. Although he had discontinued his lithium therapy 3 months before admission, he had noted symptoms of hyperthyroidism at least 1 month before admission. He was diagnosed with thyrotoxicosis due to silent thyroiditis on the basis of a high free thyroxine level, suppressed thyrotropin level, and low thyroid radioiodine uptake. We found only 10 other case reports of lithium-associated thyrotoxicosis due to silent thyroiditis.

CONCLUSION

Thyrotoxicosis caused by silent thyroiditis may be associated with lithium therapy and is likely to be underreported. The pathogenic mechanism for such cases of thyroiditis is still unclear.