Elevated thyroxine levels due to increased thyroxine-binding globulin in acute hepatitis

Two patients are presented who had unexpected increases in serum thyroxine concentration due to acquired thyroxine-binding globulin excess associated with asymptomatic hepatitis. Serum hormone concentrations were also analyzed retrospectively in 10 outpatients with viral hepatitis. Acute hepatitis is associated with an increase in serum thyroxine and thyroxine-binding globulin concentrations and a corresponding decrease in the triiodothyronine resin uptake. In five patients, serum thyroxine concentration (mean +/- SD) was elevated at 21.08 +/- 5.86 micrograms/dl during illness, and decreased to 10.18 +/- 2.96 micrograms/dl during full recovery (p less than 0.05); serum thyroxine-binding globulin concentration was elevated at 2.14 +/- 0.36 mg/dl during illness, and decreased to 1.18 +/- 0.16 mg/dl during recovery (p less than 0.01). Interpretation of thyroid function test results can be difficult in patients with hepatitis. When serum thyroxine is elevated, careful attention to a decrease in the triiodothyronine resin uptake is essential to avoid the incorrect diagnosis of hyperthyroidism. Occasionally, this change in the triiodothyronine resin uptake may be the first evidence of occult hepatic inflammation.