[Elevated thyroid hormone levels in the absence of hyperactivity]

Elevated blood levels of thyroid hormones may be due to causes other than glandular hyperactivity. We have seen transient increases in total thyroxine (TT4), free thyroxine index (FTI), free thyroxine (FT4), and total triiodothyronine (TT3) in 12 women and 3 men with subacute thyroiditis and 2 women with painless (silent) postpartum thyroiditis. Elevated TT4, FTI, and FT4 were found in 11 of 85 patients treated with amiodarone. High TT4, but not FTI or FT4, was seen in 4 women using contraceptives, in 2 pregnant women and in 2 men with liver dysfunction. All hormones, except TSH, were elevated in a patient in whom thyrotoxicosis factitia was later proved. High FTI, TT4 or FT4 but not TT3 were detected in 11 of 20 patients treated with l-throxine after surgical thyroidectomy and in 10 of 68 treated for hypothyroidism. To avoid treating when thyroxicosis is not present and to avoid reducing or stopping vital drug treatment, familiarity with these states which alter blood hormone levels is important.