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.